Possible Interaction: Alanine and Trypsin

“In each case the presence of alanine and ATP together, but not separately, reduced the rate of digestion by trypsin ; the largest effect was observed with the enzyme from rat liver.”

“Further replacement of alanine by leucine reduces the rate for thrombin, but increases the binding for trypsin.”

“The electrophoretically pure preparation which inhibits trypsin in a specific manner is a relatively small peptide containing 5 Asp, 4 Thr, 1 Ser, 11 Glu, 6 Pro, 6 Gly, 5 Ala , 2 Val, 10 (Cys)1/2, 3 Ile, 2 Phe, 7 Lys, 3 Arg and 1 Try.”

“Furthermore, substitutions of Ala by hydrophobic or hydrophilic residues decreased the activity, indicating suitable steric hindrance provides convenience for the combination of trypsin.”

“The substitution of Cys191 and Cys220 with Ala decreases the activity of trypsin by 20-200-fold as measured by kcat/K(m) for the hydrolysis of amide substrates; in contrast, ester hydrolysis is decreased by < 10-fold.”

“The Ala and Leu derivatives inhibited trypsin very weakly (Ki = 2 X 10(-7) M and 4 X 10(-7) M, respectively), and the Phe and Asp derivatives not at all.”