title: Catalytic acitivity of Ntau-carboxymethylhistidine-12 ribonuclease.
abstract: Ntau-Carboxymethylhistidine-12 RNase is active with both RNA and uridine cyclic 2':3'-monophosphate as substrates. Experimental evidence is presented to show that the activity cannot be due to contaminating RNase A, or other RNase-type protein, to the presence of a mixed dimer between 12- and 119-substituted RNases, or to the presence of trace amounts of Ntau-carboxymethylhistidine-12 RNase. The carboxymethyl derivative has approximately 1 and 13 per cent the specific activity of native enzyme against cyclic 2',3'-UMP at pH 5.0 and 8.5, respectively.
mesh_terms: D002264:Carboxylic Acids; D006639:Histidine; D006863:Hydrogen-Ion Concentration; D007461:Iodoacetates / Q000494:pharmacology; D007700:Kinetics; D009712:Nucleotides, Cyclic / Q000378:metabolism; D012260:Ribonucleases / Q000378:metabolism*; D013329:Structure-Activity Relationship; D014500:Uracil Nucleotides / Q000378:metabolism; D014529:Uridine / Q000031:analogs & derivatives
chemical_list: D002264:Carboxylic Acids; D007461:Iodoacetates; D009712:Nucleotides, Cyclic; D014500:Uracil Nucleotides; D006639:Histidine; D012260:Ribonucleases; D014529:Uridine