A model for the secondary structure of beta-lactamases.

A 3-dimensional model, common for the secondary structures of four beta-lactamases obtained from Escherichia coli, Bacillus licheniformis, Bacillus cereus and Staphylococcus aureus, is proposed. The predictions of the structures were made by the hydrophobicity profiles method complemented by the modified Chou and Fasman's method. The model proposed presents 56% constancy and can be described as a 2-domain structure, in agreement with low resolution X-ray data reported for the E. coli enzyme. The model would explain how a common function can be performed by enzymes of very different sizes, composition and sequence.