Anti-TYR (aa 300-400) polyclonal antibody

To better understand the contribution of myosin light chain (MLC) isoforms to sensory defects in Jinhua ham, dipeptidyl peptidase (DPP) activities, peptide fragments, cleavage sites and the potential of DPP to develop sensory defects of dry-cured ham were evaluated and discussed in normal and defective hams. Higher residual activities of DPP I were found in defective ham compared with normal ham; approximate 3-fold peptide fragments were identified in defective ham than in normal ham. These regions of positions 11-35 and 116-141 in MLC 1, 13-53 and 139-156 in MLC 2, and 18-50 in MLC 3 contributed to the intense generation of peptide fragments in defective ham. PLS-DA further revealed DPP I showing intense response to degrade peptides. Cleavage sites including Glu-128, Tyr-132 and Glu-133 were responsible for the intense release of dipeptides in defective ham. These cleavages could play key role in discriminating taste attributes between defective and normal hams.

Transglutaminases (TG) and arylamine N-acetyltransferases (NAT) are important family of enzymes. Although they catalyze different reactions and have distinct structures, these two families of enzymes share a spatially conserved catalytic triad (Cys, His, Asp residues). In active TGs, a conserved Trp residue located close to the triad cysteine is crucial for catalysis through stabilization of transition states. Here, we show that in addition to sharing a similar catalytic triad with TGs, functional NAT enzymes also possess in their active site an aromatic residue (Phe, Tyr or Trp) occupying a structural position similar to the Trp residue of active TGs. More importantly, as observed in active TGs, our data indicates that in functional NAT enzymes this conserved aromatic residue is also involved in stabilization of transition states. These results thus indicate that in addition to the three triad residues, these two families of enzymes also share a spatially conserved aromatic amino acid position important for catalysis. Identification of residues involved in the stabilization of transition states is important to develop potent inhibitors. Interestingly, NAT enzymes have been shown as potential targets of clinical interest. (C) 2020 Elsevier Inc. All rights reserved.