title: The effect of polycations on the activity of pepsin.
abstract: A study has been made of the interaction of selected polycations with pepsin A (E.C. 3.4.23.1). Protamine, polybrene, spermine, spermidine and poly(L-lysine) all acted as inhibitors of the enzyme at low concentrations, but at higher concentrations of the polycations the inhibition was less pronounced. A more detailed study of the anomalous inhibition was made using protamine, polybrene and poly(L-lysine) and it was shown experimentally that, when used by themselves, each of these polycations acted as a weak proteolytic catalyst. The order of catalytic effectiveness was: protamine greater than polybrene much greater than poly(L-lysine). Thus, it is now possible to explain why the observed inhibition of pepsin decreases when the concentration of the inhibiting polycation is increased.
authors.forename: J B
authors.initials: JB
authors.lastname: Lawton
authors.forename: C I
authors.initials: CI
authors.lastname: Mekas
mesh_terms: D000818:Animals; D002384:Catalysis; D002626:Chemistry, Pharmaceutical; D006454:Hemoglobins / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D066298:In Vitro Techniques; D010434:Pepsin A / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011073:Polyamines; D000071228:Polyelectrolytes; D011107:Polylysine / Q000494:pharmacology; D011108:Polymers / Q000494:pharmacology*; D011479:Protamines; D013552:Swine
chemical_list: D006454:Hemoglobins; D010434:Pepsin A; D011073:Polyamines; D000071228:Polyelectrolytes; D011107:Polylysine; D011108:Polymers; D011479:Protamines