The role of lysine-41 of ribonuclease A in the interaction with RNase inhibitor from human placenta.

摘要: 3-N-Carboxymethyl-His-12 and 1-N-carboxymethyl-His-119-RNase A bind to the naturally occurring RNase inhibitor, isolated from human placenta, 1.3 3.6 times, respectively, more strongly than does native A. Near-ultraviolet circular dichroism measurements indicate that conformational change which occurs upon carboxymethylation of either active site histidine residues appears different protein undergoes binding substrate a analogue. Specific Lys-41 decreased strength interaction between enzyme inhibitor about 12% initial value. The near-UV CD spectra Cm-Lys-41-RNase acetimidyl-RNase (9.3 lysines modified) carbamylated (3.0 modified), also have weaker interactions with 25% 10%, show negative [theta]MRW identical at 275 nm but are altered in positive 240 nm. suggest one or tyrosine may be involved inhibitor. effects pH salt concentration major part protein-protein is probably through nonpolar forces. strengths pancreatic RNases several species were very similar. Since Tyr-92 only residue retained all studied, this key role interaction. data presented herein involves positively charged epsilon-NH2 group This could result inactivation enzyme.