PMID-sentid Pub_year Sent_text comp_official_name comp_offsetprotein_name organism prot_offset 6289876-1 1982 The titration curves of the C-2 histidine protons of RNase A and of derivative II--a covalent derivative obtained by reaction of the enzyme with the halogenated nucleotide 9-beta-D-ribofuranosyl-6-chloropurine 5"-phosphate--in the presence of a number of purine nucleosides, nucleoside monophosphates, and nucleoside diphosphates were studied by means of proton nuclear magnetic resonance at 270 MHz. nucleoside monophosphates 275-300 complement C2 Bos taurus 28-31