SHV-2 β-lactamase was purified from an overproducing variant of a clinical isolate of Escherichia coli resistant to cefotaxime. Pure protein was digested by trypsin and Lys-C endoproteinase. Proteolytic peptides, isolated by reverse-phase HPLC, were submitted to manual Edman degradation and aligned by homology with the sequence of SHV-1 β-lactamase. A putative amino acid sequence was deduced. Structural comparison revealed that SHV-2 differed from SHV-1 by only one amino acid, Gly → Ser, at position 213 of the mature protein.
