Exocellular β-Lactamases of Streptomyces albus G and Strains R39 and K11

The active sites of the beta-lactamases of Streptomyces cacaoi and Streptomyces albus G.

The active-site serine of the extracellular beta-lactamases of Streptomyces cacaoi and Streptomyces albus G has been labelled with beta-iodopenicillanate. The determination of the sequence of the labelled peptides obtained after trypsin digestion of the denatured proteins indicate both enzymes to be class A beta-lactamases. Surprisingly the two Streptomyces enzymes do not appear to be especiall...

The exocellular DD-carboxypeptidase of Streptomyces albus G: a metallo (Zn2+) enzyme.

The exoceliular , B - lactamase of Streptomyces albus G

The exoceilular f-lactamase of Streptomyces albus G has been purified to near protein homogeneity. It consists of one single polypeptide chain of mol.wt. 30000-31000, has a rather low isoelectric point (at pH 6.0) and contains less lysine (2.1%) and more half-cystine residues than most fi-lactamases from other Gram-positive bacteria. Penicillins are much better substrates than A3-cephalosporins...

The penicillin-binding site in the exocellular DD-carboxypeptidase-transpeptidase of Actinomadura R39.

Heat denaturation and Pronase degradation of the complex previously formed between benzylpenicillin and the exocellular DD-carboxypeptidase-transpeptidase of Actinomadura R39 yields a heptapeptide H-Leu-Pro-Ala-Ser-Asn-Gly-Val-OH, where the benzylpenicilloyl group is ester-linked to the serine residue. This linkage is very labile and its hydrolysis causes the release of benzylpenicilloate. In c...

Peptide inhibitors of Streptomyces DD-carboxypeptidases.

1. Peptides that inhibit the dd-carboxypeptidases from Streptomyces strains albus G and R61 were synthesized. They are close analogues of the substrates of these enzymes. The enzymes from albus G and R61 strains are in general inhibited by the same peptides, but the enzyme from strain R39 differs considerably. 2. The two C-terminal residues of the peptide substrates and inhibitors appear to be ...