1979
DOI: 10.1016/0014-5793(79)80248-3
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Penicillinase active sites: Labelling of serine‐44 in β‐lactamase I by 6β‐bromopenicillanic acid

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Cited by 134 publications
(80 citation statements)
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“…Although studies with inhibitors [l-8] and poor cephalosporin and penicillin substrates [9-l 1 ] suggest the intermediacy of an acyl-enzyme, the existence of such an intermediate in the catalysis of good (specific) substrates must still be considered speculative. In fact the lack of definitive evidence for an acyl-enzyme intermediate in penicillin catalysis has been held to support a general-base-type mechanism [ 121. Studies on the site acylated by penicillin G and a specific substrate in 2 bacilliary carboxypeptidases [ 13,141 have shown striking homology with the sites of several /3-lactamases acylated by a variety of inactivators [7,15,16]. Here, we show that a covalent intermediate, consistent with an acyl-enzyme, is formed in the reaction of@lactamase I (from B. cereus 569/H) with the specific substrate dansyl-penicillin and can be trapped at low pH.…”
Section: Introductionmentioning
confidence: 56%
“…Although studies with inhibitors [l-8] and poor cephalosporin and penicillin substrates [9-l 1 ] suggest the intermediacy of an acyl-enzyme, the existence of such an intermediate in the catalysis of good (specific) substrates must still be considered speculative. In fact the lack of definitive evidence for an acyl-enzyme intermediate in penicillin catalysis has been held to support a general-base-type mechanism [ 121. Studies on the site acylated by penicillin G and a specific substrate in 2 bacilliary carboxypeptidases [ 13,141 have shown striking homology with the sites of several /3-lactamases acylated by a variety of inactivators [7,15,16]. Here, we show that a covalent intermediate, consistent with an acyl-enzyme, is formed in the reaction of@lactamase I (from B. cereus 569/H) with the specific substrate dansyl-penicillin and can be trapped at low pH.…”
Section: Introductionmentioning
confidence: 56%
“…Serine-44 of the B. cereus -lactamase I and the corresponding peptides from the'TEM-1 /3-lactamase and the S. aureus 83-lactamase can be covalently coupled to active-site-directed substrate analogues (10)(11)(12). Furthermore, serine-36 ofthe B. subtilis and B. stearothermophilus D-alanine carboxypeptidases can be covalently coupled to active-site-directed substrate analogues (9, 13).…”
Section: (-T-a-c-a-a-t-) and -35 To -30 (-T-t-g-t-c-a-) Show A Five-omentioning
confidence: 99%
“…They show significant sequence homologies with each other (7) as well as with regions of D-alanine carboxypeptidases from B. stearothermophilus and B. subtilis (9). By the use of substrate analogues, the active site has been determined for three penicillinases and two carboxypeptidases (9)(10)(11)(12)(13). They have been referred to as "serine enzymes" because the reagents react with a serine residue.…”
mentioning
confidence: 99%
“…The activity of the enzyme encoded by this gene confers tolerance to penicillin-type antibiotics. Forming a part of a reaction triad, 18,19 serine 70 is essential for the activity of this enzyme and is therefore immutable. 20 Thus, "reversion", or restoration of antibiotic resistance in this case, occurs only when a GC to TA substitution occurs in the first position of the codon 70.…”
Section: Introductionmentioning
confidence: 99%