Role of the omega-loop in the activity, substrate specificity, and structure of class A beta-lactamase

The effect of the omega-loop deletion in the function and structure of the enzyme beta-lactamases was investigated. A beta-lactamase mutant protein was produced using the four-primer overlap-extension method. A double-stranded plasmid DNA was then used to resequence the beta-lactamase gene. It was found that the absence of the omega-loop eliminated Glu166, a primary catalytic residue, thus resulting in dysfunctional deacylation. It also eliminated the enzyme's ability to hydrolyze beta-lactam compounds.