Open AccessThe Amino Acid Sequence of Mouse Pancreatic Ribonuclease
Author(s) -
LENSTRA Johannes A.,
BEINTEMA Jaap J.
Publication year - 1979
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1979.tb13199.x
Subject(s) - ribonuclease , rnase p , pancreatic ribonuclease , s tag , biology , ribonuclease iii , peptide sequence , molecular evolution , amino acid , sequence (biology) , biochemistry , bovine pancreatic ribonuclease , genetics , microbiology and biotechnology , rna , phylogenetic tree , gene , rna interference
The complete amino acid sequence of mouse pancreatic ribonuclease has been determined by analysis of tryptic, chymotryptic, thermolytic and CNBr peptides and by automatic sequence analysis of the intact protein. The sequence of mouse RNase differs in 20–30% of the positions from other RNase sequences. Three unique or nearly unique substitutions were found, viz. Gly‐68 → Arg‐68, Arg‐85 → His‐85 and Ser‐123 → Thr‐123. All these three residues might be involved in interactions with substrate molecules. A most parsimonious tree of the myomorph rodent RNase shows that after the divergence of rat and mouse, the ribonuclease of rat accumulated substitutions at a rate 2.5–4.3 times as high as the rates in other branches of the tree and 23 times as high as the average rate in the Bovidae ribonuclease evolution. These extreme fluctuations in substitution rate are difficult to reconcile with the hypothesis of the evolutionary clock. The high evolution rate of rat ribonuclease is thought to be caused by positive selection, leading to new functional properties of the enzyme.