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Interactions between beta-lactam antibiotics and isolated membranes of Streptococcus faecalis ATCC 9790.

Authors
  • Coyette, J
  • Ghuysen, J M
  • Binot, F
  • Adriaens, P
  • Meesschaert, B
  • Vanderhaeghe, H
Type
Published Article
Journal
European journal of biochemistry / FEBS
Publication Date
May 02, 1977
Volume
75
Issue
1
Pages
231–239
Identifiers
PMID: 405216
Source
Medline
License
Unknown

Abstract

The DD-carboxypeptidase-exchange membrane-bound enzyme in Streptococcus faecalis ATCC 9790 reacts with beta-lactam antibiotics to form complexes with rather long half-lives. Depending upon the antibiotic, the second-order rate constants for complex formation range from 0.75-560 M-1 S-1 (at 37 degrees C and in water) and the first-order rate constants for complex breakdown range from 1.3 to 26 x 10(-5) s-1 (at 37 degrees C and in 5 mM phosphate buffer pH 7.5). There are about 30 pmol of DD-carboxypeptidase-exchange enzyme per mg of membrane protein. The degradation products arising from benzylpenicillin are phenylacetylglycine and probably N-formyl-D-penicillamine. Isolated membranes also contain other penicillin binding sites (about 70 pmol/mg membrane protein). That part of benzylpenicillin which reacts with at least some of these latter sites is slowly degraded into penicilloic acid. Normal functioning of the DD-carboxypeptidase-exchange membrane-bound enzyme is important, if not essential, for cell growth. With the beta-lactam antibiotics tested inhibition of cell growth is mainly related to the rates of formation of the inactive enzyme-antibiotic complexes. The relationship, however, is not a direct one probably due to the competitive effect exerted by the other penicillin binding sites.

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