Open AccessStabilization of the C‐Terminal Part of Pig and Horse Colipase by Carboxypeptidase and Trypsin Inhibitors
Author(s) -
CHAPUS Catherine,
DESNUELLE Pierre,
FOGLIZZO Edith
Publication year - 1981
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1981.tb06203.x
Subject(s) - cyanogen bromide , carboxypeptidase , trypsin , chemistry , horse , biochemistry , cleavage (geology) , stereochemistry , methionine , histidine , cofactor , peptide , amino acid , peptide sequence , enzyme , biology , paleontology , fracture (geology) , gene
Pig and horse colipases have been purified by a common procedure using trypsin and carboxypeptidase inhibitors as stabilizers. Two forms of pig colipase were identified: a predominant A1 form with about 103–105 residues, and a minor slightly degraded A2 form in which the last two C‐terminal residues, Asp and Ser, were lacking. This type of degradation is considerably slowed down by carboxypeptidase inhibitors. A total of four forms of the horse cofactor were characterized: two (A1 and B1) were probably isocolipases which differed by only a few substitutions. Both contained the same number of residues (about 96), an N‐terminal valine and an Arg‐Ser‐Glu‐(Glx) 1,2 ‐Arg C‐terminal sequence. A2 and B2 were slightly degraded forms probably resulting from tryptic cleavage of the Arg‐Ser bond in the above sequence. The presence of methioriine in the horse cofactor allowed fragmentation by cyanogen bromide. The C‐terminal fragment was composed of 16 or 17 residues and contained no histidine. The single histidine of horse B1 was found in the intermediary fragment between Met‐18 and Met‐( n ‐16) or Met‐( n ‐I7). These data show that the C‐terminal parts of both pig and horse colipases are still more exposed to proteolytic degradations than the N‐terminal parts. Preliminary attempts to crystallize B1 were carried out.