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B6db activities: cold

cold
Description GDP-4-dehydro-6-deoxy-D-mannose-3-dehydratase (4.3.1.-)
Alternative names GDP-4-oxo-6-deoxy-D-mannose-3-dehydratase;
ColD.
Catalyzed reaction GDP-4-dehydro-6-deoxy-D-mannose + L-glutamate = GDP-4-dehydro-3,6-dideoxy-D-mannose + 2-oxoglutarate + NH3
Cofactor Pyridoxal-phosphate
Comments The overall reaction proposedly includes (i) a half-transamination, in which glutamate reacts with PLP, generating oxoglutarate and PMP. (ii) Condensation of PMP with GDP-4-keto-6-deoxy-D-mannose, to yield the respective ketoimine. (iii) elimination of the 3-hydroxy group from the mannose moyety, with formation of the external aldimine of GDP-6-deoxy-4-amino-delta(3,4)-mannooseen (iv) hydrolysis of the aldimine linkage (regenerating PLP) and hydration of the double bond in the mannoseen ring, releasing ammonia and yielding the final carbohydrate product, GDP-4-keto-3,6-dideoxy-D-mannose
The enzyme is involved in the biosynthesis of colitose, a 3,6-dideoxysugar that has been isolated from the O-antigen of certain Gram-negative bacteria such as Escherichia coli, Yersinia pseudotuberculosis, Salmonella enterica, Vibrio cholerae, and in marine bacteria such as Pseudoalteromonas sp.
This enzyme is related to the E1 protein of CDP-4-dehydro-6-deoxyglucose reductase (EC 1.17.1.1) and shares with the latter the absence of an active site lysine - meaning that PLP is not covalently bound to the enzyme through an internal aldimine linkage.
PDB 2GMS; 2GMU;
Organisms -Eubacteria
 

Family 

cold (5)
 
Links Enzyme (activities) cold
BRENDA (activities) cold
KEGG (pathways) cold
PLPMDB (PLP mutants) cold
 
References Articles on cold
 
last changed 2010/01/27 18:03

B6db activities