Isolation and characterization of four peptide hydrolases from the brush border of rat intestinal mucosa

摘要: Peptide hydrolases (EC 3.4.-.-) were solubilized from purified brush borders of rat intestinal mucosa by papain digestion. Three peptide hydrolases, I, II, and III, with different substrate specificities isolated means DEAE-cellulose chromatography preparative acrylamide gel electrophoresis. On repeat electrophoresis under slightly conditions, enzyme II was resolved into two proteins, IIa IIb, vary similar, possibly identical, specificities. Efforts to discover additional border revealed none. Studies using more than 50 substrates showed that I most active against Met-Met, Met-Ala, Met-Phe while Phe-Gly, Phe-Ser, Leu-Gly-Gly, III rapidly hydrolyzed Gly-Leu, Leu-Gly, Met-Gly. which are highly discriminating for each partly successful. Thus, a number including leucine amide, leucyl-beta-naphthylamide Phe-Asp almost exclusively (95% or more) Gly-Leu similarly specific III. No discovered. Ion-exchange resulted in increases activity 10- 120-fold enzymes respectively. By sequential use ion-exchange electrophoresis, the three partially point they free contaminating disaccharidases gave single dense bands on analytical band plus one faint protein band. Under appropriate also activity. The germ-free rats indicating none is bacterial origin. With Phe-Gly as substrate, pH optima 8.0, 8.5, Molecular weights determined filtration 283 000, 284 134 activation metal ions inhibition ion chelators suggested dependent relatively tightly bound cofactor. play an essential role studies presented here help clarify total these border.