Open AccessRat‐Proinsulin C‐Peptides
Author(s) -
Markussen Jan,
Sundby Finn
Publication year - 1972
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1972.tb01680.x
Subject(s) - residue (chemistry) , proinsulin , alanine , amino acid , biochemistry , lysine , arginine , peptide , threonine , glutamic acid , chemistry , moiety , glycine , stereochemistry , biology , serine , insulin , enzyme , endocrinology
The amino acid sequences of two rat C‐peptides corresponding to two rat proinsulins have been elucidated. Both C‐peptides have 31 amino acids. There are differences in two positions, namely, in position 8 where rat‐I has a proline and rat‐II an alanine residue, and in position 17 where rat‐I has a glutamic acid, rat‐II a glycine residue. The additional acidic residue in rat‐I C‐peptide is counteracted by the additional basic residue in the insulin moiety of rat‐I proinsulin (lysine B 29), which provides the two proinsulins with the same net charge at neutral pH. The amino acid sequences are:The rat C‐peptides contain threonine and arginine, neither of which is present in the C‐peptides of man, pig and ox. A comparison of the 5 sequences shows only 10 identical positions out of 31.