Molecular insights into the mechanism of substrate recognition of transglutaminases.

The microbial TGase from has used in various food industries. However, the detailed substrate specificities of TGases from the species toward the natural peptides remains to be unclear. In this study, we conducted the comparison of two different TGases from (SMTG) and (SCTG).

Enzymatic Degradation of Allergen Peptides from Bovine Casein by a Combination of Streptomyces Aminopeptidases.

Cow's milk is one of the most common allergenic foods. Cow's milk allergy is mainly an IgE-mediated hypersensitivity reaction, and the major allergens from cow's milk have been found to be caseins, β-lactoglobulin, and α-lactalbumin. Several peptides derived from bovine casein are known allergens in cow's milk.

Methionine residues lining the substrate pathway in prolyl oligopeptidase from Pleurotus eryngii play an important role in substrate recognition.

Family S9 prolyl oligopeptidases (POPs) are of interest as pharmacological targets. We recently found that an S9 POP from Pleurotus eryngii showed altered substrate specificity following HO treatment. Oxidation of Met203 on the non-catalytic β-propeller domain resulted in decreased activity toward non-aromatic aminoacyl-para-nitroanilides (pNAs) while maintaining its activity toward aromatic aminoacyl-pNAs.

Effect of oxidation of the non-catalytic β-propeller domain on the substrate specificity of prolyl oligopeptidase from Pleurotus eryngii.

Enzymes belonging to the S9 family of prolyl oligopeptidases are of interest because of their pharmacological importance and have a non-catalytic β-propeller domain. In this study, we found that the oxidation of Met203, which lies on surface of the β-propeller domain, leads to change in the substrate specificity of eryngase, an enzyme from Pleurotus eryngii and a member of the S9 family of prolyl oligopeptidases. The activity of eryngase for L-Phe-p-nitroanilide was maintained following hydrogen peroxide treatment but was dramatically reduced for other p-nitroanilide substrates.

Gene cloning and biochemical characterization of eryngase, a serine aminopeptidase of Pleurotus eryngii belonging to the family S9 peptidases.

Pleurotus eryngii serine aminopeptidase that has peptide bond formation activity, redesignated as eryngase, was cloned and expressed. Eryngase has a family S9 peptidase unit in the C-terminal region having a catalytic triad of Ser, Asp, and His. In the phylogenetic relations among the subfamilies of family S9 peptidase (S9A, prolyl oligopeptidase; S9B, dipeptidyl peptidase; S9C, acylaminoacyl peptidase; S9D, glutamyl endopeptidase), eryngase existed alone in the neighbor of S9C subfamily.