title: Comparison of the structure of turtle pancreatic ribonuclease with those of mammalian ribonucleases.
abstract: There are 33 invariant amino acid positions out of 132 positions in 42 investigated sequences of ribonucleases from a number of mammalian species and a reptile (snapping turtle, Chelydra serpentina). These invariant residues are unequally distributed over 3 different parts of the molecule. The lobe of the S-protein part of the molecule, which lacks one disulfide bridge and has two shortened loops in turtle ribonuclease, has the lowest percentage of invariant residues, although the active-site residue His 119 is located in this part.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D004722:Endoribonucleases / Q000302:isolation & purification; D046911:Macromolecular Substances; D010446:Peptide Fragments / Q000302:isolation & purification; D011487:Protein Conformation; D012260:Ribonucleases / Q000302:isolation & purification; D013045:Species Specificity; D014426:Turtles
chemical_list: D046911:Macromolecular Substances; D010446:Peptide Fragments; C023560:ribonuclease S-peptide; D004722:Endoribonucleases; D012260:Ribonucleases; C032523:ribonuclease SPL