The origin and properties of beta-lactamase satellite bands seen in isoelectric focusing.

Citrobacter diversus 2046E and Branhamella catarrhalis 2001E each produce a constitutive, chromosomally mediated broad-spectrum beta-lactamase. Isoelectric focusing of both enzymes revealed patterns of multiple 'satellite' bands. The principal satellite bands of each enzyme were isolated and characterized. Individual bands of each enzyme gave similar substrate profiles, molecular weights and responses to inhibitors to one another. The results support the theory that satellite bands are due to the loss and/or modification of specific amino acid residues resulting in biologically active molecules with altered nett charges.