The most significant difference between BlaC and other class A β-lactamase active sites is the lack of Asn132 in the former, in which it is replaced by Gly . Asn132 may help to keep the 6α-1R-hydroxyethyl dihedral in Position II, thereby lowering the barriers to reaction in carbapenemases. Previous structural and computational studies have suggested that interactions of Asn132 with the 6α-1R-hydroxyethyl group are important in determining carbapenemase activity . Comparisons between enzymes here (e.g. SFC-1 and TEM-1), show that this residue is less flexible in carbapenem-inhibited enzymes than carbapenemases, due to increased interaction between Asn132 and the 6α-1R-hydroxyethyl in the carbapenem hydrolyzing enzymes.