L-xylulose reductase
L-Xylulose reductase tetramer, Human
Identifiers
EC no.	1.1.1.10
Databases
IntEnz	IntEnz view
BRENDA	BRENDA entry
ExPASy	NiceZyme view
KEGG	KEGG entry
MetaCyc	metabolic pathway
PRIAM	profile
PDB structures	RCSB PDB PDBe PDBsum
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dicarbonyl/L-xylulose reductase
Identifiers
Symbol	DCXR
NCBI gene	51181
HGNC	18985
OMIM	608347
RefSeq	NM_016286
UniProt	Q7Z4W1
Other data
EC number	1.1.1.10
Locus	Chr. 17 q25.3
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Dicarbonyl/L-xylulose reductase, also known as carbonyl reductase II, is an enzyme that in human is encoded by the DCXR gene located on chromosome 17.

Structure

The DCXR gene encodes a membrane protein that is approximately 34 kDa in size and composed of 224 amino acids. The protein is highly expressed in the kidney and localizes to the cytoplasmic membrane.^[1]

Function

DCSR catalyzes the reduction of several L-xylylose as well as a number of pentoses, tetroses, trioses, alpha-dicarbonyl compounds. The enzyme is involved in carbohydrate metabolism, glucose metabolism, the uronate cycle and may play a role in the water absorption and cellular osmoregulation in the proximal renal tubules by producing xylitol.^[2]

In enzymology, an L-xylulose reductase (EC 1.1.1.10) is an enzyme that catalyzes the chemical reaction

xylitol + NADP⁺ ${\displaystyle \rightleftharpoons }$ L-xylulose + NADPH + H⁺

Thus, the two substrates of this enzyme are xylitol and NADP⁺, whereas its 3 products are L-xylulose, NADPH, and H⁺.

• 
  Xylulose
• 
  Xylitol (Note conversion of ketone to alcohol)

This enzyme belongs to the superfamily of short-chain oxidoreductases, specifically those acting on the CH-OH group of donor with NAD⁺ or NADP⁺ as acceptor. The systematic name of this enzyme class is xylitol:NADP⁺ 2-oxidoreductase (L-xylulose-forming).

Clinical significance

A deficiency is responsible for pentosuria. The insufficiency of L-xylulose reductase activity causes an inborn error of metabolism disease characterized by excessive urinary excretion of L-xylulose.

Over-expression and ectopic expression of the protein may be associated with prostate adenocarcinoma.^[3]