title: Preparation of cross-linked dimers of pancreatic ribonuclease.
abstract: The cross-linking reaction between diimido esters and ribonuclease has been studied in terms of the yield of cross-linked dimer with optimum activity toward double-stranded RNA. With dimethyl suberimidate the most satisfactory conditions were condensation for 15 min at pH 7.5-8.0 at 21 degrees C with 1.25 mol equiv of the diimido ester and a protein concentration of 6%. The dimer (yield 20%) had 19 unmodified NH2 groups out of a theoretical 20 for a molecule in which two such groups are involved in the cross-linkage; the activity toward poly(A)-poly(U) in 0.14 M salt solution by spectrophotometric assay was 8.5 times that of the monomeric enzyme toward the same substrate.
mesh_terms: D000818:Animals; D001665:Binding Sites; D002417:Cattle; D004120:Dimethyl Suberimidate; D007094:Imides; D046911:Macromolecular Substances; D010179:Pancreas / Q000201:enzymology*; D011485:Protein Binding; D012260:Ribonucleases / Q000378:metabolism; D013329:Structure-Activity Relationship
chemical_list: D007094:Imides; D046911:Macromolecular Substances; D004120:Dimethyl Suberimidate; D012260:Ribonucleases