Untersuchungen zum Einfluß von Cu++ -Ionen auf die Aktivität von Trypsin bei VerWendung Natürlicher Substrate

Abstract

In vitro experiments were carried out in order to investigate the influence of Cu++-ions on the tryptic hydrolysis of casein and soybean protein. The admixture of 10(-3) to 10(-2) Mol Cu++/l to the reaction preparations results in the activation of trypsin in both substrates. The further increase of the Cu++-concentration results in a decrease of the trypsin activity and, with casein as substrate, in trypsin inhibition. The effects are similar with the synthetic substrate N alpha-benzoyl-L-arginine-p-nitroamilide (L-BAPA), however, trypsin is already activated after the admixture of approximately 5 x 10(-6) Mol Cu++/l. Since the admixture of Cu++-ions in experiments with pepsin in similar concentrations as with trypsin also results in an activation, the question is being discussed whether the improved protein digestibility and the higher weight increase of pigs which received 250 ppm copper can be traced back to these effects.

Quantitative serine protease assays based on formation of copper(ii)–oligopeptide complexes

“…Serine proteases such as trypsin and chymotrypsin were used as model proteases because their activities are not inhibited by Cu 2+ . 25 To detect the activity of trypsin, we designed an oligopeptide substrate GGGGKGGH (P 1 ), which consists of a potential trypsin cleavage site at lysine (K) and a terminal tripeptide residue of GGH. In Tris buffer (pH 8.0), P 1 is able to form a weak complex with Cu 2+ through imidazole nitrogen and peptide bonds, 26 as is evident by a strong absorption peak around 565 nm (Fig.…”

Einfluss verschiedener Spurenelemente auf die tryptische Hydrolyse

“…Bei Erhöhung der Ionenkonzentration im Versuchsansatz ist bei Trypsin eine zunehmende Aktivitätsminderung zu beobachten. Die Versuche bestätigen damit Angaben, in denen höhere Zn++-Konzentrationen verwendet wurden (10,11,17,22 (20). Dabei zeigten sich bei Cu++-Zusatz die gleichen Effekte wie beim synthetischen Substrat.…”