Lysozyme (EC3.2.1.17, muramidase, N-acetylmuramide glycanhydrolase; systematic name peptidoglycan N-acetylmuramoylhydrolase) is an antimicrobial enzyme produced by animals that forms part of the innate immune system. It is a glycoside hydrolase that catalyzes the following process:
Hydrolysis of (1→4)-β-linkages between N-acetylmuramic acid and N-acetyl-D-glucosamine residues in a peptidoglycan and between N-acetyl-D-glucosamine residues in chitodextrins
Peptidoglycan is the major component of gram-positive bacterial cell wall.[1] This hydrolysis in turn compromises the integrity of bacterial cell walls causing lysis of the bacteria.
Hen egg white lysozyme is thermally stable, with a melting point reaching up to 72 °C at pH 5.0.[5] However, lysozyme in human milk loses activity very quickly at that temperature.[6] Hen egg white lysozyme maintains its activity in a large range of pH (6–9).[7] Its isoelectric point is 11.35.[8] The isoelectric point of human milk lysozyme is 10.5–11.[9]
Lysozyme's active site binds the peptidoglycan molecule in the prominent cleft between its two domains. It attacks peptidoglycans (found in the cell walls of bacteria, especially Gram-positive bacteria), its natural substrate, between N-acetylmuramic acid (NAM) and the fourth carbon atom of N-acetylglucosamine (NAG).
Shorter saccharides like tetrasaccharide have also shown to be viable substrates but via an intermediate with a longer chain.[11] Chitin has also been shown to be a viable lysozyme substrate. Artificial substrates have also been developed and used in lysozyme.[12]
Mechanism
Phillips
The Phillips mechanism proposed that the enzyme's catalytic power came from both steric strain on the bound substrate and electrostatic stabilization of an oxo-carbenium intermediate. From X-ray crystallographic data, Phillips proposed the active site of the enzyme, where a hexasaccharide binds. The lysozyme distorts the fourth sugar (in the D or -1 subsite) in the hexasaccharide into a half-chair conformation. In this stressed state, the glycosidic bond is more easily broken.[13] An ionic intermediate containing an oxo-carbenium is created as a result of the glycosidic bond breaking.[14] Thus distortion causing the substrate molecule to adopt a strained conformation similar to that of the transition state will lower the energy barrier of the reaction.[15]
The proposed oxo-carbonium intermediate was speculated to be electrostatically stabilized by aspartate and glutamate residues in the active site by Arieh Warshel in 1978. The electrostatic stabilization argument was based on comparison to bulk water, the reorientation of water dipoles can cancel out the stabilizing energy of charge interaction. In Warshel's model, the enzyme acts as a super-solvent, which fixes the orientation of ion pairs and provides super-solvation (very good stabilization of ion pairs), and especially lower the energy when two ions are close to each other.[16]
The rate-determining step (RDS) in this mechanism is related to formation of the oxo-carbenium intermediate. There were some contradictory results to indicate the exact RDS. By tracing the formation of product (p-nitrophenol), it was discovered that the RDS can change over different temperatures, which was a reason for those contradictory results. At a higher temperature the RDS is formation of glycosyl enzyme intermediate and at a lower temperature the breakdown of that intermediate.[17]
Covalent intermediate of lysozyme enzyme, with covalent bond in black and experimental evidence as blue mesh.[18]
Covalent mechanism
Substrates in Vocadlo's experiment
In an early debate in 1969, Dahlquist proposed a covalent mechanism for lysozyme based on kinetic isotope effect,[14] but for a long time the ionic mechanism was more accepted. In 2001, a revised mechanism was proposed by Vocadlo via a covalent but not ionic intermediate. Evidence from ESI-MS analysis indicated a covalent intermediate. A 2-fluoro substituted substrate was used to lower the reaction rate and accumulate an intermediate for characterization.[19] The amino acid side-chains glutamic acid 35 (Glu35) and aspartate 52 (Asp52) have been found to be critical to the activity of this enzyme. Glu35 acts as a proton donor to the glycosidic bond, cleaving the C-O bond in the substrate, whereas Asp52 acts as a nucleophile to generate a glycosyl enzyme intermediate. The Glu35 reacts with water to form hydroxyl ion, a stronger nucleophile than water, which then attacks the glycosyl enzyme intermediate, to give the product of hydrolysis and leaving the enzyme unchanged.[20] This type of covalent mechanism for enzyme catalysis was first proposed by Koshland.[21]
More recently, quantum mechanics/ molecular mechanics (QM/MM) molecular dynamics simulations have been using the crystal of HEWL and predict the existence of a covalent intermediate.[22] Evidence for the ESI-MS and X-ray structures indicate the existence of covalent intermediate, but primarily rely on using a less active mutant or non-native substrate. Thus, QM/MM molecular dynamics provides the unique ability to directly investigate the mechanism of wild-type HEWL and native substrate. The calculations revealed that the covalent intermediate from the covalent mechanism is ~30 kcal/mol more stable than the ionic intermediate from the Phillips mechanism.[22] These calculations demonstrate that the ionic intermediate is extremely energetically unfavorable and the covalent intermediates observed from experiments using less active mutant or non-native substrates provide useful insight into the mechanism of wild-type HEWL.
Despite that the muramidase activity of lysozyme has been supposed to play the key role for its antibacterial properties, evidence of its non-enzymatic action was also reported. For example, blocking the catalytic activity of lysozyme by mutation of critical amino acid in the active site (52-Asp -> 52-Ser) does not eliminate its antimicrobial activity.[25] The lectin-like ability of lysozyme to recognize bacterial carbohydrate antigen without lytic activity was reported for tetrasaccharide related to lipopolysaccharide of Klebsiella pneumoniae.[26] Also, lysozyme interacts with antibodies and T-cell receptors.[27]
Enzyme conformation changes
Lysozyme exhibits two conformations: an open active state and a closed inactive state. The catalytic relevance was examined with single walled carbon nanotubes (SWCN) field effect transistors (FETs), where a singular lysozyme was bound to the SWCN FET.[28] Electronically monitoring the lysozyme showed two conformations, an open active site and a closed inactive site. In its active state lysozyme is able to processively hydrolyze its substrate, breaking on average 100 bonds at a rate of 15 per second. In order to bind a new substrate and move from the closed inactive state to the open active state requires two conformation step changes, while inactivation requires one step.
Superfamily
The conventional C-type lysozyme is part of a larger group of structually and mechanistically related enzymes termed the lysozyme superfamily. This family unites GH22 C-type ("chicken") lysozymes with plant chitinase GH19, G-type ("goose") lysozyme GH23, V-type ("viral") lysozyme GH24 and the chitosanase GH46 families. The lysozyme-type nomenclature only reflects the source a type is originally isolated from and does not fully reflect the taxonomic distribution.[29] For example, humans and many other mammals have two G-type lysozyme genes, LYG1 and LYG2.[30]
Lysozyme is part of the innate immune system. Reduced lysozyme levels have been associated with bronchopulmonary dysplasia in newborns.[35] Piglets fed with human lysozyme milk can recover from diarrheal disease caused by E. coli faster. The concentration of lysozyme in human milk is 1,600 to 3,000 times greater than the concentration in livestock milk. Human lysozyme is more active than hen egg white lysozyme. A transgenic line of goats (with a founder named "Artemis") were developed to produce milk with human lysozyme to protect children from diarrhea if they can't get the benefits of human breastfeeding.[36][37]
Since lysozyme is a natural form of protection from Gram-positive pathogens like Bacillus and Streptococcus,[38] it plays an important role in immunology of infants in human milk feeding.[39] Whereas the skin is a protective barrier due to its dryness and acidity, the conjunctiva (membrane covering the eye) is, instead, protected by secreted enzymes, mainly lysozyme and defensin. However, when these protective barriers fail, conjunctivitis results.
In certain cancers (especially myelomonocytic leukemia) excessive production of lysozyme by cancer cells can lead to toxic levels of lysozyme in the blood. High lysozyme blood levels can lead to kidney failure and low blood potassium, conditions that may improve or resolve with treatment of the primary malignancy.
Serum lysozyme is much less specific for diagnosis of sarcoidosis than serum angiotensin converting enzyme; however, since it is more sensitive, it is used as a marker of sarcoidosis disease activity and is suitable for disease monitoring in proven cases.[40]
Chemical synthesis
The first chemical synthesis of a lysozyme protein was attempted by Prof. George W. Kenner and his group at the University of Liverpool in England.[41] This was finally achieved in 2007 by Thomas Durek in Steve Kent's lab at the University of Chicago who made a synthetic functional lysozyme molecule.[42]
Other applications
Lysozyme crystals have been used to grow other functional materials for catalysis and biomedical applications.[43][44][45] Lysozyme is a commonly used enzyme for lysing gram positive bacteria.[46] Due to the unique function of lysozyme in which it can digest the cell wall and causes osmotic shock (burst the cell by suddenly changing solute concentration around the cell and thus the osmotic pressure), lysozyme is commonly used in lab setting to release proteins from bacterium periplasm while the inner membrane remains sealed as vesicles called the spheroplast.[47][48]
For example, E. coli can be lysed using lysozyme to free the contents of the periplasmic space. It is especially useful in lab setting for trying to collect the contents of the periplasm.[1] Lysozyme treatment is optimal at particular temperatures, pH ranges, and salt concentrations. Lysozyme activity increases with increasing temperatures, up to 60 degrees Celsius, with a pH range of 6.0-7.0. The salts present also affect lysozyme treatment, where some assert inhibitory effects, and others promote lysis via lysozyme treatment. Sodium chloride induces lysis, but at high concentrations, it is an active inhibitor of lysis. Similar observations have been seen with the use of potassium salts. Slight variations are present due to differences in bacterial strains.[49] A consequence of the use of lysozyme in extracting recombinant proteins for protein crystallization is that the crystal may be contaminated with units of lysozyme, producing a physiologically irrelevant combination. In fact, some proteins simply cannot crystalize without such contamination.[50][51]
Furthermore, lysozyme can serve as a tool in the expression of toxic recombinant proteins. Expressing recombinant proteins in BL21(DE3) strains is typically accomplished by the T7-RNA-polymerase. Via IPTG induction, the UV-5 repressor is inhibited, leading to the transcription of the T7-RNA-polymerase and thereby of the protein of interest. Nonetheless, a basal level of the T7-RNA-polymerase is observable even without induction. T7 lysozyme acts as an inhibitor of the T7-RNA-polymerase. Newly invented strains, containing a helper plasmid (pLysS), constitutively co-express low levels of T7 lysozyme, providing high stringency and consistent expression of the toxic recombinant protein.[52]
History
The antibacterial property of hen egg white, due to the lysozyme it contains, was first observed by Laschtschenko in 1909.[53] The bacteria-killing activity of nasal mucus was demonstrated in 1922 by Alexander Fleming, the discoverer of penicillin, who coined the term lysozyme.[54] Fleming reported, saying. "As this substance has properties akin to those of ferments I have called it a 'Lysozyme'."[55] Fleming went on to show that an enzymic substance was present in a wide variety of secretions and was capable of rapidly lysing (i.e. dissolving) different bacteria, particularly a yellow "coccus" that he studied".[56]
Lysozyme was first crystallised by Edward Abraham in 1937, enabling the three-dimensional structure of hen egg white lysozyme to be described by David Chilton Phillips in 1965, when he obtained the first 2-ångström (200 pm) resolution model via X-ray crystallography.[57][58] The structure was publicly presented at a Royal Institution lecture in 1965.[59]
Lysozyme was the second protein structure and the first enzyme structure to be solved via X-ray diffraction methods, and the first enzyme to be fully sequenced that contains all twenty common amino acids.[60]
As a result of Phillips' elucidation of the structure of lysozyme, it was also the first enzyme to have a detailed, specific mechanism suggested for its method of catalytic action.[61][62][63] This work led Phillips to provide an explanation for how enzymes speed up a chemical reaction in terms of its physical structures. The original mechanism proposed by Phillips was more recently revised.[19]
^Yoshimura K, Toibana A, Nakahama K (January 1988). "Human lysozyme: sequencing of a cDNA, and expression and secretion by Saccharomyces cerevisiae". Biochemical and Biophysical Research Communications. 150 (2): 794–801. doi:10.1016/0006-291X(88)90461-5. PMID2829884.
^Skujiņś J, Puķite A, McLaren AD (December 1973). "Adsorption and reactions of chitinase and lysozyme on chitin". Molecular and Cellular Biochemistry. 2 (2): 221–228. doi:10.1007/BF01795475. PMID4359167. S2CID27906558.
^Blake CC, Johnson LN, Mair GA, North AC, Phillips DC, Sarma VR (April 1967). "Crystallographic studies of the activity of hen egg-white lysozyme". Proceedings of the Royal Society of London. Series B, Biological Sciences. 167 (1009): 378–388. Bibcode:1967RSPSB.167..378B. doi:10.1098/rspb.1967.0035. PMID4382801. S2CID35094695.
^ abDahlquist FW, Rand-Meir T, Raftery MA (October 1969). "Application of secondary α-deuterium kinetic isotope effects to studies of enzyme catalysis. Glycoside hydrolysis by lysozyme and β-glucosidase". Biochemistry. 8 (10): 4214–4221. doi:10.1021/bi00838a045. PMID5388150.
^ abBowman AL, Grant IM, Mulholland AJ (October 2008). "QM/MM simulations predict a covalent intermediate in the hen egg white lysozyme reaction with its natural substrate". Chemical Communications (37): 4425–4427. doi:10.1039/b810099c. PMID18802578.
^Swan ID (March 1972). "The inhibition of hen egg-white lysozyme by imidazole and indole derivatives". Journal of Molecular Biology. 65 (1): 59–62. doi:10.1016/0022-2836(72)90491-3. PMID5063023.
^Grivel JC, Smith-Gill SJ (1996). Lysozyme: Antigenic structure as defined by antibody and T cell responses. CRC Press. pp. 91–144. ISBN978-0-8493-9225-2.
^Tomita H, Sato S, Matsuda R, Sugiura Y, Kawaguchi H, Niimi T, et al. (1999). "Serum lysozyme levels and clinical features of sarcoidosis". Lung. 177 (3): 161–167. doi:10.1007/pl00007637. PMID10192763. S2CID3999327.
^Wei H, Wang Z, Zhang J, House S, Gao YG, Yang L, et al. (February 2011). "Time-dependent, protein-directed growth of gold nanoparticles within a single crystal of lysozyme". Nature Nanotechnology. 6 (2): 93–97. Bibcode:2011NatNa...6...93W. doi:10.1038/nnano.2010.280. PMID21278750.
^Sanghamitra NJ, Ueno T (May 2013). "Expanding coordination chemistry from protein to protein assembly". Chemical Communications. 49 (39): 4114–4126. doi:10.1039/C2CC36935D. PMID23211931.
^Laschtschenko P (1909). "Über die keimtötende und entwicklungshemmende Wirkung Hühnereiweiß" [On the germ-killing and growth-inhibiting effect chicken egg albumin]. Zeitschrift für Hygiene und Infektionskrankheiten (in German). 64: 419–427. doi:10.1007/BF02216170. S2CID456259.
133l: ROLE OF ARG 115 IN THE CATALYTIC ACTION OF HUMAN LYSOZYME. X-RAY STRUCTURE OF HIS 115 AND GLU 115 MUTANTS
134l: ROLE OF ARG 115 IN THE CATALYTIC ACTION OF HUMAN LYSOZYME. X-RAY STRUCTURE OF HIS 115 AND GLU 115 MUTANTS
1b5u: CONTRIBUTION OF HYDROGEN BONDS TO THE CONFORMATIONAL STABILITY OF HUMAN LYSOZYME: CALORIMETRY AND X-RAY ANALYSIS OF SIX SER->ALA MUTANT
1b5v: CONTRIBUTION OF HYDROGEN BONDS TO THE CONFORMATIONAL STABILITY OF HUMAN LYSOZYME: CALORIMETRY AND X-RAY ANALYSIS OF SIX SER->ALA MUTANTS
1b5w: CONTRIBUTION OF HYDROGEN BONDS TO THE CONFORMATIONAL STABILITY OF HUMAN LYSOZYME: CALORIMETRY AND X-RAY ANALYSIS OF SIX SER->ALA MUTANTS
1b5x: Contribution of hydrogen bonds to the conformational stability of human lysozyme: calorimetry and x-ray analysis of six ser->ala mutants
1b5y: CONTRIBUTION OF HYDROGEN BONDS TO THE CONFORMATIONAL STABILITY OF HUMAN LYSOZYME: CALORIMETRY AND X-RAY ANALYSIS OF SIX SER->ALA MUTANTS
1b5z: CONTRIBUTION OF HYDROGEN BONDS TO THE CONFORMATIONAL STABILITY OF HUMAN LYSOZYME: CALORIMETRY AND X-RAY ANALYSIS OF SIX SER->ALA MUTANTS
1b7l: VERIFICATION OF SPMP USING MUTANT HUMAN LYSOZYMES
1b7m: VERIFICATION OF SPMP USING MUTANT HUMAN LYSOZYMES
1b7n: VERIFICATION OF SPMP USING MUTANT HUMAN LYSOZYMES
1b7o: VERIFICATION OF SPMP USING MUTANT HUMAN LYSOZYMES
1b7p: VERIFICATION OF SPMP USING MUTANT HUMAN LYSOZYMES
1b7q: VERIFICATION OF SPMP USING MUTANT HUMAN LYSOZYMES
1b7r: VERIFICATION OF SPMP USING MUTANT HUMAN LYSOZYMES
1b7s: VERIFICATION OF SPMP USING MUTANT HUMAN LYSOZYMES
1bb3: HUMAN LYSOZYME MUTANT A96L
1bb4: HUMAN LYSOZYME DOUBLE MUTANT A96L, W109H
1bb5: HUMAN LYSOZYME MUTANT A96L COMPLEXED WITH CHITOTRIOSE
1c43: MUTANT HUMAN LYSOZYME WITH FOREIGN N-TERMINAL RESIDUES
1c45: MUTANT HUMAN LYSOZYME WITH FOREIGN N-TERMINAL RESIDUES
1c46: MUTANT HUMAN LYSOZYME WITH FOREIGN N-TERMINAL RESIDUES
1c7p: CRYSTAL STRUCTURE OF MUTANT HUMAN LYSOZYME WITH FOUR EXTRA RESIDUES (EAEA) AT THE N-TERMINAL
1cj6: T11A MUTANT HUMAN LYSOZYME
1cj7: T11V MUTANT HUMAN LYSOZYME
1cj8: T40A MUTANT HUMAN LYSOZYME
1cj9: T40V MUTANT HUMAN LYSOZYME
1ckc: T43A MUTANT HUMAN LYSOZYME
1ckd: T43V MUTANT HUMAN LYSOZYME
1ckf: T52A MUTANT HUMAN LYSOZYME
1ckg: T52V MUTANT HUMAN LYSOZYME
1ckh: T70V MUTANT HUMAN LYSOZYME
1d6p: HUMAN LYSOZYME L63 MUTANT LABELLED WITH 2',3'-EPOXYPROPYL N,N'-DIACETYLCHITOBIOSE
1d6q: HUMAN LYSOZYME E102 MUTANT LABELLED WITH 2',3'-EPOXYPROPYL GLYCOSIDE OF N-ACETYLLACTOSAMINE
1di3: ROLE OF AMINO ACID RESIDUES AT TURNS IN THE CONFORMATIONAL STABILITY AND FOLDING OF HUMAN LYSOZYME
1di4: ROLE OF AMINO ACID RESIDUES AT TURNS IN THE CONFORMATIONAL STABILITY AND FOLDING OF HUMAN LYSOZYME
1di5: ROLE OF AMINO ACID RESIDUES AT TURNS IN THE CONFORMATIONAL STABILITY AND FOLDING OF HUMAN LYSOZYME
1eq4: CRYSTAL STRUCTURES OF SALT BRIDGE MUTANTS OF HUMAN LYSOZYME
1eq5: CRYSTAL STRUCTURES OF SALT BRIDGE MUTANTS OF HUMAN LYSOZYME
1eqe: CRYSTAL STRUCTURES OF SALT BRIDGE MUTANTS OF HUMAN LYSOZYME
1gay: CRYSTAL STRUCTURE OF MUTANT HUMAN LYSOZYME SUBSTITUTED AT THE SURFACE POSITIONS
1gaz: Crystal Structure of Mutant Human Lysozyme Substituted at the Surface Positions
1gb0: CRYSTAL STRUCTURE OF MUTANT HUMAN LYSOZYME SUBSTITUTED AT THE SURFACE POSITIONS
1gb2: CRYSTAL STRUCTURE OF MUTANT HUMAN LYSOZYME SUBSTITUTED AT THE SURFACE POSITIONS
1gb3: CRYSTAL STRUCTURE OF MUTANT HUMAN LYSOZYME SUBSTITUTED AT THE SURFACE POSITIONS
1gb5: CRYSTAL STRUCTURE OF MUTANT HUMAN LYSOZYME SUBSTITUTED AT THE SURFACE POSITIONS
1gb6: CRYSTAL STRUCTURE OF MUTANT HUMAN LYSOZYME SUBSTITUTED AT THE SURFACE POSITIONS
1gb7: CRYSTAL STRUCTURE OF MUTANT HUMAN LYSOZYME SUBSTITUTED AT THE SURFACE POSITIONS
1gb8: CRYSTAL STRUCTURE OF MUTANT HUMAN LYSOZYME SUBSTITUTED AT THE SURFACE POSITIONS
1gb9: CRYSTAL STRUCTURE OF MUTANT HUMAN LYSOZYME SUBSTITUTED AT THE SURFACE POSITIONS
1gbo: CRYSTAL STRUCTURE OF MUTANT HUMAN LYSOZYME SUBSTITUTED AT THE SURFACE POSITIONS
1gbw: CRYSTAL STRUCTURE OF MUTANT HUMAN LYSOZYME SUBSTITUTED AT THE SURFACE POSITIONS
1gbx: CRYSTAL STRUCTURE OF MUTANT HUMAN LYSOZYME SUBSTITUTED AT THE SURFACE POSITIONS
1gby: CRYSTAL STRUCTURE OF MUTANT HUMAN LYSOZYME SUBSTITUTED AT THE SURFACE POSITIONS
1gbz: CRYSTAL STRUCTURE OF MUTANT HUMAN LYSOZYME SUBSTITUTED AT THE SURFACE POSITIONS
1gdw: CRYSTAL STRUCTURE OF MUTANT HUMAN LYSOZYME SUBSTITUTED AT LEFT-HANDED HELICAL POSITIONS
1gdx: CRYSTAL STRUCTURE OF MUTANT HUMAN LYSOZYME SUBSTITUTED AT LEFT-HANDED HELICAL POSITIONS
1ge0: CRYSTAL STRUCTURE OF MUTANT HUMAN LYSOZYME SUBSTITUTED AT LEFT-HANDED HELICAL POSITIONS
1ge1: CRYSTAL STRUCTURE OF MUTANT HUMAN LYSOZYME SUBSTITUTED AT LEFT-HANDED HELICAL POSITIONS
1ge2: CRYSTAL STRUCTURE OF MUTANT HUMAN LYSOZYME SUBSTITUTED AT LEFT-HANDED HELICAL POSITIONS
1ge3: CRYSTAL STRUCTURE OF MUTANT HUMAN LYSOZYME SUBSTITUTED AT LEFT-HANDED HELICAL POSITIONS
1ge4: CRYSTAL STRUCTURE OF MUTANT HUMAN LYSOZYME SUBSTITUTED AT LEFT-HANDED HELICAL POSITIONS
1gev: BURIED POLAR MUTANT HUMAN LYSOZYME
1gez: BURIED POLAR MUTANT HUMAN LYSOZYME
1gf0: BURIED POLAR MUTANT HUMAN LYSOZYME
1gf3: BURIED POLAR MUTANT HUMAN LYSOZYME
1gf4: BURIED POLAR MUTANT HUMAN LYSOZYME
1gf5: BURIED POLAR MUTANT HUMAN LYSOZYME
1gf6: BURIED POLAR MUTANT HUMAN LYSOZYME
1gf7: BURIED POLAR MUTANT HUMAN LYSOZYME
1gf8: CRYSTAL STRUCTURE OF MUTANT HUMAN LYSOZYME SUBSTITUTED AT THE SURFACE POSITIONS
1gf9: CRYSTAL STRUCTURE OF MUTANT HUMAN LYSOZYME SUBSTITUTED AT THE SURFACE POSITIONS
1gfa: CRYSTAL STRUCTURE OF MUTANT HUMAN LYSOZYME SUBSTITUTED AT THE SURFACE POSITIONS
1gfe: CRYSTAL STRUCTURE OF MUTANT HUMAN LYSOZYME SUBSTITUTED AT THE SURFACE POSITIONS
1gfg: CRYSTAL STRUCTURE OF MUTANT HUMAN LYSOZYME SUBSTITUTED AT THE SURFACE POSITIONS
1gfh: CRYSTAL STRUCTURE OF MUTANT HUMAN LYSOZYME SUBSTITUTED AT THE SURFACE POSITIONS
1gfj: CRYSTAL STRUCTURE OF MUTANT HUMAN LYSOZYME SUBSTITUTED AT THE SURFACE POSITIONS
1gfk: CRYSTAL STRUCTURE OF MUTANT HUMAN LYSOZYME SUBSTITUTED AT THE SURFACE POSITIONS
1gfr: CRYSTAL STRUCTURE OF MUTANT HUMAN LYSOZYME SUBSTITUTED AT THE SURFACE POSITIONS
1gft: CRYSTAL STRUCTURE OF MUTANT HUMAN LYSOZYME SUBSTITUTED AT THE SURFACE POSITIONS
1gfu: CRYSTAL STRUCTURE OF MUTANT HUMAN LYSOZYME SUBSTITUTED AT THE SURFACE POSITIONS
1gfv: CRYSTAL STRUCTURE OF MUTANT HUMAN LYSOZYME SUBSTITUTED AT THE SURFACE POSITIONS
1hnl: CRYSTAL STRUCTURE OF A GLUTATHIONYLATED HUMAN LYSOZYME: A FOLDING INTERMEDIATE MIMIC IN THE FORMATION OF A DISULFIDE BOND
1i1z: MUTANT HUMAN LYSOZYME (Q86D)
1i20: MUTANT HUMAN LYSOZYME (A92D)
1i22: MUTANT HUMAN LYSOZYME (A83K/Q86D/A92D)
1inu: CRYSTAL STRUCTURE OF MUTANT HUMAN LYSOZYME SUBSTITUTED AT THE SURFACE POSITIONS
1ioc: CRYSTAL STRUCTURE OF MUTANT HUMAN LYSOZYME, EAEA-I56T
1ip1: G37A HUMAN LYSOZYME
1ip2: G48A HUMAN LYSOZYME
1ip3: G68A HUMAN LYSOZYME
1ip4: G72A HUMAN LYSOZYME
1ip5: G105A HUMAN LYSOZYME
1ip6: G127A HUMAN LYSOZYME
1ip7: G129A HUMAN LYSOZYME
1iwt: Crystal Structure Analysis of Human lysozyme at 113K.
1iwu: Crystal Structure Analysis of Human lysozyme at 127K.
1iwv: Crystal Structure Analysis of Human lysozyme at 147K.
1iww: Crystal Structure Analysis of Human lysozyme at 152K.
1iwx: Crystal Structure Analysis of Human lysozyme at 161K.
1iwy: Crystal Structure Analysis of Human lysozyme at 170K.
1iwz: Crystal Structure Analysis of Human lysozyme at 178K.
1ix0: I59A-3SS human lysozyme
1iy3: Solution Structure of the Human lysozyme at 4 degree C
1iy4: Solution structure of the human lysozyme at 35 degree C
1jka: HUMAN LYSOZYME MUTANT WITH GLU 35 REPLACED BY ASP
1jkb: HUMAN LYSOZYME MUTANT WITH GLU 35 REPLACED BY ALA
1jkc: HUMAN LYSOZYME MUTANT WITH TRP 109 REPLACED BY PHE
1jkd: HUMAN LYSOZYME MUTANT WITH TRP 109 REPLACED BY ALA
1jsf: FULL-MATRIX LEAST-SQUARES REFINEMENT OF HUMAN LYSOZYME
1jwr: Crystal structure of human lysozyme at 100 K
1laa: X-RAY STRUCTURE OF GLU 53 HUMAN LYSOZYME
1lhh: ROLE OF PROLINE RESIDUES IN HUMAN LYSOZYME STABILITY: A SCANNING CALORIMETRIC STUDY COMBINED WITH X-RAY STRUCTURE ANALYSIS OF PROLINE MUTANTS
1lhi: ROLE OF PROLINE RESIDUES IN HUMAN LYSOZYME STABILITY: A SCANNING CALORIMETRIC STUDY COMBINED WITH X-RAY STRUCTURE ANALYSIS OF PROLINE MUTANTS
1lhj: ROLE OF PROLINE RESIDUES IN HUMAN LYSOZYME STABILITY: A SCANNING CALORIMETRIC STUDY COMBINED WITH X-RAY STRUCTURE ANALYSIS OF PROLINE MUTANTS
1lhk: ROLE OF PROLINE RESIDUES IN HUMAN LYSOZYME STABILITY: A SCANNING CALORIMETRIC STUDY COMBINED WITH X-RAY STRUCTURE ANALYSIS OF PROLINE MUTANTS
1lhl: ROLE OF PROLINE RESIDUES IN HUMAN LYSOZYME STABILITY: A SCANNING CALORIMETRIC STUDY COMBINED WITH X-RAY STRUCTURE ANALYSIS OF PROLINE MUTANTS
1lhm: THE CRYSTAL STRUCTURE OF A MUTANT LYSOZYME C77(SLASH)95A WITH INCREASED SECRETION EFFICIENCY IN YEAST
1lmt: STRUCTURE OF A CONFORMATIONALLY CONSTRAINED ARG-GLY-ASP SEQUENCE INSERTED INTO HUMAN LYSOZYME
1loz: AMYLOIDOGENIC VARIANT (I56T) VARIANT OF HUMAN LYSOZYME
1lyy: AMYLOIDOGENIC VARIANT (ASP67HIS) OF HUMAN LYSOZYME
1lz1: REFINEMENT OF HUMAN LYSOZYME AT 1.5 ANGSTROMS RESOLUTION. ANALYSIS OF NON-BONDED AND HYDROGEN-BOND INTERACTIONS
1lz4: ENTHALPIC DESTABILIZATION OF A MUTANT HUMAN LYSOZYME LACKING A DISULFIDE BRIDGE BETWEEN CYSTEINE-77 AND CYSTEINE-95
1lz5: STRUCTURAL AND FUNCTIONAL ANALYSES OF THE ARG-GLY-ASP SEQUENCE INTRODUCED INTO HUMAN LYSOZYME
1lz6: STRUCTURAL AND FUNCTIONAL ANALYSES OF THE ARG-GLY-ASP SEQUENCE INTRODUCED INTO HUMAN LYSOZYME
1lzr: STRUCTURAL CHANGES OF THE ACTIVE SITE CLEFT AND DIFFERENT SACCHARIDE BINDING MODES IN HUMAN LYSOZYME CO-CRYSTALLIZED WITH HEXA-N-ACETYL-CHITOHEXAOSE AT PH 4.0
1lzs: STRUCTURAL CHANGES OF THE ACTIVE SITE CLEFT AND DIFFERENT SACCHARIDE BINDING MODES IN HUMAN LYSOZYME CO-CRYSTALLIZED WITH HEXA-N-ACETYL-CHITOHEXAOSE AT PH 4.0
1op9: Complex of human lysozyme with camelid VHH HL6 antibody fragment
1oua: CONTRIBUTION OF HYDROPHOBIC RESIDUES TO THE STABILITY OF HUMAN LYSOZYME: X-RAY STRUCTURE OF THE I56T MUTANT
1oub: CONTRIBUTION OF HYDROPHOBIC RESIDUES TO THE STABILITY OF HUMAN LYSOZYME: X-RAY STRUCTURE OF THE V100A MUTANT
1ouc: CONTRIBUTION OF HYDROPHOBIC RESIDUES TO THE STABILITY OF HUMAN LYSOZYME: X-RAY STRUCTURE OF THE V110A MUTANT
1oud: CONTRIBUTION OF HYDROPHOBIC RESIDUES TO THE STABILITY OF HUMAN LYSOZYME: X-RAY STRUCTURE OF THE V121A MUTANT
1oue: CONTRIBUTION OF HYDROPHOBIC RESIDUES TO THE STABILITY OF HUMAN LYSOZYME: X-RAY STRUCTURE OF THE V125A MUTANT
1ouf: CONTRIBUTION OF HYDROPHOBIC RESIDUES TO THE STABILITY OF HUMAN LYSOZYME: X-RAY STRUCTURE OF THE V130A MUTANT
1oug: CONTRIBUTION OF HYDROPHOBIC RESIDUES TO THE STABILITY OF HUMAN LYSOZYME: X-RAY STRUCTURE OF THE V2A MUTANT
1ouh: CONTRIBUTION OF HYDROPHOBIC RESIDUES TO THE STABILITY OF HUMAN LYSOZYME: X-RAY STRUCTURE OF THE V74A MUTANT
1oui: CONTRIBUTION OF HYDROPHOBIC RESIDUES TO THE STABILITY OF HUMAN LYSOZYME: X-RAY STRUCTURE OF THE V93A MUTANT
1ouj: CONTRIBUTION OF HYDROPHOBIC RESIDUES TO THE STABILITY OF HUMAN LYSOZYME: X-RAY STRUCTURE OF THE V99A MUTANT
1qsw: CRYSTAL STRUCTURE ANALYSIS OF A HUMAN LYSOZYME MUTANT W64C C65A
1re2: HUMAN LYSOZYME LABELLED WITH TWO 2',3'-EPOXYPROPYL BETA-GLYCOSIDE OF N-ACETYLLACTOSAMINE
1rem: HUMAN LYSOZYME WITH MAN-B1,4-GLCNAC COVALENTLY ATTACHED TO ASP53
1rex: NATIVE HUMAN LYSOZYME
1rey: HUMAN LYSOZYME-N,N'-DIACETYLCHITOBIOSE COMPLEX
1rez: HUMAN LYSOZYME-N-ACETYLLACTOSAMINE COMPLEX
1tay: DISSECTION OF THE FUNCTIONAL ROLE OF STRUCTURAL ELEMENTS OF TYROSINE-63 IN THE CATALYTIC ACTION OF HUMAN LYSOZYME
1tby: DISSECTION OF THE FUNCTIONAL ROLE OF STRUCTURAL ELEMENTS OF TYROSINE-63 IN THE CATALYTIC ACTION OF HUMAN LYSOZYME
1tcy: DISSECTION OF THE FUNCTIONAL ROLE OF STRUCTURAL ELEMENTS OF TYROSINE-63 IN THE CATALYTIC ACTION OF HUMAN LYSOZYME
1tdy: DISSECTION OF THE FUNCTIONAL ROLE OF STRUCTURAL ELEMENTS OF TYROSINE-63 IN THE CATALYTIC ACTION OF HUMAN LYSOZYME
1ubz: Crystal structure of Glu102-mutant human lysozyme doubly labeled with 2',3'-epoxypropyl beta-glycoside of N-acetyllactosamine
1w08: STRUCTURE OF T70N HUMAN LYSOZYME
1wqm: CONTRIBUTION OF HYDROGEN BONDS TO THE CONFORMATIONAL STABILITY OF HUMAN LYSOZYME
1wqn: CONTRIBUTION OF HYDROGEN BONDS TO THE CONFORMATIONAL STABILITY OF HUMAN LYSOZYME
1wqo: CONTRIBUTION OF HYDROGEN BONDS TO THE CONFORMATIONAL STABILITY OF HUMAN LYSOZYME
1wqp: CONTRIBUTION OF HYDROGEN BONDS TO THE CONFORMATIONAL STABILITY OF HUMAN LYSOZYME
1wqq: CONTRIBUTION OF HYDROGEN BONDS TO THE CONFORMATIONAL STABILITY OF HUMAN LYSOZYME
1wqr: CONTRIBUTION OF HYDROGEN BONDS TO THE CONFORMATIONAL STABILITY OF HUMAN LYSOZYME
1yam: CONTRIBUTION OF HYDROPHOBIC RESIDUES TO THE STABILITY OF HUMAN LYSOZYME: CALORIMETRIC STUDIES AND X-RAY STRUCTURAL ANALYSIS OF THE FIVE ISOLEUCINE TO VALINE MUTANTS
1yan: CONTRIBUTION OF HYDROPHOBIC RESIDUES TO THE STABILITY OF HUMAN LYSOZYME: CALORIMETRIC STUDIES AND X-RAY STRUCTURAL ANALYSIS OF THE FIVE ISOLEUCINE TO VALINE MUTANTS
1yao: CONTRIBUTION OF HYDROPHOBIC RESIDUES TO THE STABILITY OF HUMAN LYSOZYME: CALORIMETRIC STUDIES AND X-RAY STRUCTURAL ANALYSIS OF THE FIVE ISOLEUCINE TO VALINE MUTANTS
1yap: CONTRIBUTION OF HYDROPHOBIC RESIDUES TO THE STABILITY OF HUMAN LYSOZYME: CALORIMETRIC STUDIES AND X-RAY STRUCTURAL ANALYSIS OF THE FIVE ISOLEUCINE TO VALINE MUTANTS
1yaq: CONTRIBUTION OF HYDROPHOBIC RESIDUES TO THE STABILITY OF HUMAN LYSOZYME: CALORIMETRIC STUDIES AND X-RAY STRUCTURAL ANALYSIS OF THE FIVE ISOLEUCINE TO VALINE MUTANTS
207l: MUTANT HUMAN LYSOZYME C77A
208l: MUTANT HUMAN LYSOZYME C77A
2bqa: CONTRIBUTION OF HYDROPHOBIC EFFECT TO THE CONFORMATIONAL STABILITY OF HUMAN LYSOZYME
2bqb: CONTRIBUTION OF HYDROPHOBIC EFFECT TO THE CONFORMATIONAL STABILITY OF HUMAN LYSOZYME
2bqc: CONTRIBUTION OF HYDROPHOBIC EFFECT TO THE CONFORMATIONAL STABILITY OF HUMAN LYSOZYME
2bqd: CONTRIBUTION OF HYDROPHOBIC EFFECT TO THE CONFORMATIONAL STABILITY OF HUMAN LYSOZYME
2bqe: CONTRIBUTION OF HYDROPHOBIC EFFECT TO THE CONFORMATIONAL STABILITY OF HUMAN LYSOZYME
2bqf: CONTRIBUTION OF HYDROPHOBIC EFFECT TO THE CONFORMATIONAL STABILITY OF HUMAN LYSOZYME
2bqg: CONTRIBUTION OF HYDROPHOBIC EFFECT TO THE CONFORMATIONAL STABILITY OF HUMAN LYSOZYME
2bqh: CONTRIBUTION OF HYDROPHOBIC EFFECT TO THE CONFORMATIONAL STABILITY OF HUMAN LYSOZYME
2bqi: CONTRIBUTION OF HYDROPHOBIC EFFECT TO THE CONFORMATIONAL STABILITY OF HUMAN LYSOZYME
2bqj: CONTRIBUTION OF HYDROPHOBIC EFFECT TO THE CONFORMATIONAL STABILITY OF HUMAN LYSOZYME
2bqk: CONTRIBUTION OF HYDROPHOBIC EFFECT TO THE CONFORMATIONAL STABILITY OF HUMAN LYSOZYME
2bql: CONTRIBUTION OF HYDROPHOBIC EFFECT TO THE CONFORMATIONAL STABILITY OF HUMAN LYSOZYME
2bqm: CONTRIBUTION OF HYDROPHOBIC EFFECT TO THE CONFORMATIONAL STABILITY OF HUMAN LYSOZYME
2bqn: CONTRIBUTION OF HYDROPHOBIC EFFECT TO THE CONFORMATIONAL STABILITY OF HUMAN LYSOZYME
2bqo: CONTRIBUTION OF HYDROPHOBIC EFFECT TO THE CONFORMATIONAL STABILITY OF HUMAN LYSOZYME
2hea: CONTRIBUTION OF WATER MOLECULES IN THE INTERIOR OF A PROTEIN TO THE CONFORMATIONAL STABILITY
2heb: CONTRIBUTION OF WATER MOLECULES IN THE INTERIOR OF A PROTEIN TO THE CONFORMATIONAL STABILITY
2hec: CONTRIBUTION OF WATER MOLECULES IN THE INTERIOR OF A PROTEIN TO THE CONFORMATIONAL STABILITY
2hed: CONTRIBUTION OF WATER MOLECULES IN THE INTERIOR OF A PROTEIN TO THE CONFORMATIONAL STABILITY
2hee: CONTRIBUTION OF WATER MOLECULES IN THE INTERIOR OF A PROTEIN TO THE CONFORMATIONAL STABILITY
2hef: CONTRIBUTION OF WATER MOLECULES IN THE INTERIOR OF A PROTEIN TO THE CONFORMATIONAL STABILITY
2lhm: CRYSTAL STRUCTURES OF THE APO-AND HOLOMUTANT HUMAN LYSOZYMES WITH AN INTRODUCED CA2+ BINDING SITE
2mea: CHANGES IN CONFORMATIONAL STABILITY OF A SERIES OF MUTANT HUMAN LYSOZYMES AT CONSTANT POSITIONS
2meb: CHANGES IN CONFORMATIONAL STABILITY OF A SERIES OF MUTANT HUMAN LYSOZYMES AT CONSTANT POSITIONS
2mec: CHANGES IN CONFORMATIONAL STABILITY OF A SERIES OF MUTANT HUMAN LYSOZYMES AT CONSTANT POSITIONS
2med: CONTRIBUTION OF HYDROPHOBIC EFFECT TO THE CONFORMATIONAL STABILITY OF HUMAN LYSOZYME
2mee: CONTRIBUTION OF HYDROPHOBIC EFFECT TO THE CONFORMATIONAL STABILITY OF HUMAN LYSOZYME
2mef: CONTRIBUTION OF HYDROPHOBIC EFFECT TO THE CONFORMATIONAL STABILITY OF HUMAN LYSOZYME
2meg: CHANGES IN CONFORMATIONAL STABILITY OF A SERIES OF MUTANT HUMAN LYSOZYMES AT CONSTANT POSITIONS.
2meh: CONTRIBUTION OF HYDROPHOBIC EFFECT TO THE CONFORMATIONAL STABILITY OF HUMAN LYSOZYME
2mei: CONTRIBUTION OF HYDROPHOBIC EFFECT TO THE CONFORMATIONAL STABILITY OF HUMAN LYSOZYME
2nwd: Structure of chemically synthesized human lysozyme at 1 Angstrom resolution
3lhm: CRYSTAL STRUCTURES OF THE APO-AND HOLOMUTANT HUMAN LYSOZYMES WITH AN INTRODUCED CA2+ BINDING SITE