A modified enzyme comprising a mutation selected from the group consisting of N101S, I123T, Y134F, Y134V, L137I, V140I, S161P, V174A, Q200E, V231A, V311A, T336S, M337G, A339G, S340A, Y344A, Y344G, Y344V, K388N, E483D, C576A and combinations thereof in an amino acid sequence selected from the group consisting of:
- (A) the amino acid sequence of SEQ ID NO:
- 1;
- (B) the amino acid sequence of (A), but comprising a further mutation comprising substitution, deletion, insertion, or addition of one to thirty amino acid residues;
- and
- (C) the amino acid sequence of (A), but comprising additional mutations of one or more amino acid residues and having 95% or more identity to the amino acid sequence of (A), and
- wherein said modified enzyme has an N-acylation activity comprising:
- (i) an N-acylation activity to L-glutamic acid and/or L-aspartic acid;
- and/or
- (ii) a substrate specificity to L-glutamic acid;
- wherein the N-acylation activity is improved over a non-modified enzyme consisting of the amino acid sequence of SEQ ID NO:
- 1.