Information on EC 6.3.2.28 - L-amino-acid alpha-ligase

The enzyme from Bacillus sp. requires Mg²⁺ or Mn²⁺ for activity. While the enzyme has extremely broad substrate specificity, it does not accept highly charged amino acids, such as Lys, Arg, Glu and Asp, nor does it react with secondary amines such as Pro. The N-terminal residue of the -dipeptide formed seems to be limited to Ala, Gly, Ser, Thr and Met (with Ala and Ser being the most preferred), whereas the C-terminal residue seems to allow for a wider variety of amino acids (but with a preference for Met and Phe). However, not all combinations or dipeptides are formed. For example, while Ser is acceptable for the N-terminus and Thr for the C-terminus, a Ser-Thr dipeptide is not formed. D-Ala, D-Ser and D-Phe are not substrates. Belongs in the ATP-dependent carboxylate-amine/thiol ligase superfamily.