Purification and biochemical properties of Pitton's type 2 beta-lactamase (SHV-1).
A five-step procedure has been developed for purifying Pitton's type 2 plasmid-mediated beta-lactamase (PIT-2, also called SHV-1) from cultures of a hyperproducing variant of an Escherichia coli K12 strain carrying the plasmid p453. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis revealed a single protein band with a molecular weight of about 27,500. The amino acid composition of the protein and the amino acid sequence of the NH2-terminal region have been determined. PIT-2 enzyme contains 272 amino acid residues with 2 cysteines. Studies of the S-carboxymethylated protein (previously reduced or unreduced) suggest that these two residues are presumably in the form of free sulphydryl groups in the native protein. Conversely, TEM-2 beta-lactamase contains 2 cysteine residues which are in the form of a disulphide bond. Comparison of PIT-2 with other beta-lactamases was made using the difference index (DI) of Metzger et al. The PIT-2 enzyme appeared more closely related to the TEM-type penicillinases (DI of 6.5).
Barthélémy
M
M
Muséum National d'Histoire Naturelle, CNRS UA 401, Paris.
Peduzzi
J
J
Verchère-Beaur
C
C
Ben Yaghlane
H
H
Labia
R
R
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D008722:Methods; D008969:Molecular Sequence Data; D010957:Plasmids; D001618:beta-Lactamases / Q000032:analysis / Q000302:isolation & purification
D000596:Amino Acids; C054882:beta-lactamase PIT-2; D001618:beta-Lactamases