The amino acid sequence of pike-whale (lesser-rorqual) pancreatic ribonuclease

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Abstract
Pancreatic RNAase (ribonuclease) from the pike whale (lesser rorqual, Balaenoptera acutorostrata) was isolated by affinity chromatography. The protein was digested with different proteolytic enzymes. Peptides were isolated by gel filtration, preparative high-voltage paper electrophoresis and paper chromatography. The amino acid sequence of peptides was determined by the dansyl-Edman method. An amino acid composition was not determined for the whole protein; but all peptide bonds were overlapped by one or more peptides. Residues 85-96 are bridged by a peptide of unsatisfactory composition and the sequence here depends, at least in part, on homology for its confirmation. Another region in which a similar situation obtains is Residues 39-40 are similar to this situation. This pancreatic RNAase differs at 24-33% of the positions from all other mammalian pancreatic RNAases sequenced to date, except for pig RNAase, from which it differs by 19%. This indicates that whale RNAase has evolved independently during the larger part of the evolution of the mammals. Lesser-rorqual pancreatic RNAase is partially glycosidated (30%) at asparagine-76 in an Asn-Ser-Thr sequence (residues 76-78). Pig RNAase also has carbohydrate attached to asparagine-76 and is identical with lesser-rorqual RNAase in residues 76-98.