@article {4557,
	title = {Catalytic acid/base residues of glutamate racemase},
	journal = {Biochemistry},
	volume = {38},
	number = {13},
	year = {1999},
	note = {ISI Document Delivery No.: 182QZTimes Cited: 43Cited Reference Count: 37},
	month = {Mar},
	pages = {4106-4113},
	type = {Article},
	abstract = {Glutamate racemase is a cofactor-independent enzyme that employs two active-site cysteine residues as acid/base catalysts during the interconversion of glutamate enantiomers, In a given reaction direction, a thiolate from one of the cysteines abstracts the alpha-proton, and the other cysteine thiol delivers a proton to the opposite face of the resulting carbanionic intermediate. This paper reports that the C73S and C184S mutants are still capable of racemizing glutamate with specificity constants about 10(3)-fold lower than those of the wild-type enzyme, A "one-base requiring" reaction, the elimination of water from N-hydroxyglutamate, has been used to deduce which thiol acts as the base for a given enantiomer. With D-N-hydroxyglutamate the C73S mutant is a much poorer catalyst than wild-type enzyme, whereas the C184S mutant is a somewhat better catalyst. This trend was reversed with L-N-hydroxyglutamate, suggesting that Cys73 is responsible for the deprotonation of D-glutamate and Cys184 is responsible for the deprotonation of L-glutamate. In addition, with C73S the V-max/K-M isotope effect on D-glutamate racemization was greater than that seen with wild-type enzyme, whereas the isotope effect with L-glutamate had decreased. The results were reversed with the C184S mutant. This is interpreted as being due to an asymmetry in the free energy profiles that is induced upon mutation, with the deprotonation step involving a serine becoming the more cleanly rate-determining of the two. These results support the above assignment and the notion that a carbanionic intermediate is formed during catalysis.},
	keywords = {BACILLUS-STEAROTHERMOPHILUS, DIAMINOPIMELATE EPIMERASE, ENERGETICS, ESCHERICHIA-COLI, INHIBITOR, IRREVERSIBLE, L-ALANINE, MANDELATE RACEMASE, MECHANISM, PROLINE RACEMASE, PURIFICATION},
	isbn = {0006-2960},
	url = {<Go to ISI>://000079510800031},
	author = {Glavas, S. and Tanner, M. E.}
}
@article {3983,
	title = {The inhibition of glutamate racemase by D-N-hydroxyglutamate},
	journal = {Bioorganic \& Medicinal Chemistry Letters},
	volume = {7},
	number = {17},
	year = {1997},
	note = {ISI Document Delivery No.: XX507Times Cited: 20Cited Reference Count: 30},
	month = {Sep},
	pages = {2265-2270},
	type = {Article},
	abstract = {We report that D-N-hydroxyglutamate is ii competitive inhibitor of glutamate racemase (K-I=56 mu M). The compound acts as an alternate substrate and is converted into a-ketoglutarate and ammonia (K-M=57 mu M, k(cat)/K-M=3.2x10(3) M(-1)sec(-1)), An imine intermediate is likely the species causing the inhibition. L-N-hydroxyglutamate is a weak inhibitor and is slowly converted to alpha-ketoglutarate (k(cat)/K-M=30 M(-1)sec(-1)). (C) 1997 Elsevier Science Ltd.},
	keywords = {CLONING, DIAMINOPIMELIC ACID, EPIMERASE, ESCHERICHIA-COLI, GENE, L-ALANINE, LACTOBACILLUS, MURI, PEDIOCOCCUS-PENTOSACEUS, resistance},
	isbn = {0960-894X},
	url = {<Go to ISI>://A1997XX50700025},
	author = {Glavas, S. and Tanner, M. E.}
}
