Primary structure of fox (Vulpes vulpes) proinsulin based on sequence studies of pancreatic peptides and cDNA

Insulin and C-peptide were extracted and purified from fox (Vulpes vulpes) pancreas using gel filtration, ion-exchange chromatography and HPLC. Chroma tographic data for the insulin, as well as for its oxidized and carboxymeth ylated chains proved it to be identical to that of polar fox (Alopex lagopu s) and dog. The sequence analysis of a peptide which was assumed to be the corresponding C-peptide revealed that it comprises 23 amino acid residues a nd is identical to the C-peptide fragment isolated from dog pancreas; it di ffers from polar fox C-peptide by a single substitution (Asp --> Glu). mRNA was isolated from pancreatic tissue and cDNA was obtained by reverse trans cription. A polymerase chain reaction was performed using gene-specific pri mers to obtain a DNA fragment corresponding to part of fox proinsulin. DNA sequencing revealed 100% Identity to dog proinsulin at the protein level. a lthough some amino acids were encoded by different codons. The total sequen ce of proinsulin was deduced from these results. Copyright (C) 2000 Europea n Peptide Society and John Wiley & Sons, Ltd.