Open AccessThe Amino‐Acid Sequence of Kangaroo Pancreatic Ribonuclease
Author(s) -
GAASTRA Wim,
WELLING Gjalt W.,
BEINTEMA Jaap J.
Publication year - 1978
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1978.tb12301.x
Subject(s) - biology , pancreatic ribonuclease , ribonuclease , biochemistry , peptide sequence , serine , bovine pancreatic ribonuclease , s tag , ribonuclease t1 , amino acid , residue (chemistry) , pancreatic polypeptide , microbiology and biotechnology , enzyme , rnase p , rna , gene , glucagon , hormone
Red kangaroo (Macropus rufus) ribonuclease was isolated from pancreatic tissue by affinity chromatography. The amino acid sequence was determined by automatic sequencing of overlapping large fragments and by analysis of shorter peptides obtained by digestion with a number of proteolytic enzymes. The polypeptide chain consists of 122 amino acid residues. Compared to other ribonucleases, the N‐terminal residue and residue 114 are deleted. In other pancreatic ribonucleases position 114 is occupied by a cis proline residue in an external loop at the surface of the molecule. Other remarkable substitutions are the presence of a tyrosine residue at position 123 instead of a serine which forms a hydrogen bond with the pyrimidine ring of a nucleotide substrate, and a number of hydrophobic‐hydrophilic interchanges in the sequence 51–55, which forms part of an α‐helix in bovine ribonuclease and exhibits few substitutions in the placental mammals. Kangaroo ribonuclease contains no carbohydrate, although the enzyme possesses a recognition site for carbohydrate attachment in the sequence Asn‐Val‐Thr (62–64). The enzyme differs at about 35–40% of the positions from all other mammalian pancreatic ribonucleases sequenced to date, which is in agreement with the early divergence between the marsupials and the placental mammals. From fragmentary data a tentative sequence of red‐necked wallaby (Macropus rufogriseus) pancreatic ribonuclease has been derived. Eight differences with the kangaroo sequence were found.