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  • Title: Identification of an essential glutamic acid residue in beta-lactamase II from Bacillus cereus.
    Author: Little C, Emanuel EL, Gagnon J, Waley SG.
    Journal: Biochem J; 1986 Jan 15; 233(2):465-9. PubMed ID: 2869754.
    Abstract:
    Beta-Lactamase II from Bacillus cereus was readily inactivated by incubation at pH 4.75 with a water-soluble carbodiimide plus a suitable nucleophile. In the early stages of the reaction, 1 equivalent of nucleophile was incorporated/equivalent of enzyme, whereas during the later stages a second equivalent of nucleophile was also incorporated. This latter process correlated with the blocking of the enzyme's single thiol group. Enzyme inactivated in the presence of the coloured nucleophile N-(2,4-dinitrophenyl)ethylenediamine was fragmented by pepsin digestion, and coloured peptides were isolated by gel filtration and h.p.l.c. Two major peptides, representing 52% of the incorporated label, were isolated and sequenced. Both peptides contained the incorporated label on glutamic acid-37, and it is concluded that this latter residue represents a catalytically essential carboxylic residue in beta-lactamase II.
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