Alister James Moody

The primary structure of porcine glicentin (proglucagon)

The primary structure of porcine glicentin has been established. The molecule consists of 69 amino acid residues and has a molecular weight of 8128. The sequence of glicentin 1-30 represents the glicentin-related pancreatic peptide (GRPP) previously isolated from porcine pancreas. The sequence 33-61 represents the full sequence of glucagon and the sequence 64-69 is a C-terminal hexapeptide. These three sequences, GRPP, glucagon and the hexapeptide are linked by two Lys-Arg pairs which probably represent the sites for post-synthetic enzymatic cleavages. Glicentin thus fulfils the structural requirements for being proglucagon.

The isolation and sequencing of human gastric inhibitory peptide (GIP)

Human GIP 1–42 and fragments of human GIP corresponding to GIP 10–42, GIP 11–42, and GIP 17–42 were isolated from acid‐ethanol extracts of human small intestines with the aid of an anti‐GIP serum specific for the extreme C‐terminal portion of the GIP molecule. The full sequence of human GIP has been established by Edman degradation of these peptides and fragments thereof by automatic gas‐phase sequencing. Human GIP differs from porcine GIP at residues 18 and 34. The sequence of human GIP is thus: Tyr‐Ala‐Glu‐Gly‐Thr‐Phe‐Ile‐Ser‐Asp‐Tyr‐Ser‐Ile‐Ala‐Met‐Asp‐Lys‐Ile‐His‐Gln‐Gln‐Asp‐Phe‐5 10 15 20 Val‐Asn‐Trp‐Leu‐Leu‐Ala‐Glu‐Lys‐Gly‐Lys‐Lys‐Asn‐Asp‐Trp,Lys‐His‐Asn‐Ile‐Thr‐Gln. Amino acid 25 30 35 40 residues 18 and 34 are Arg and Ser, respectively, in porcine GIP.

Purification and chemical characterization of a glicentin-related pancreatic peptide (proglucagon fragment) from porcine pancreas.

Abstract A glicentin-related peptide has been isolated from porcine pancreas in a highly purified form. Starting with a side-fraction from the production of porcine insulin (corresponding to 140 kg pancreas), a total of 10.8 mg glicentin-related pancreatic peptide was obtained. The purification was approx. 10 6 -times and the yield about 8%. The glicentin-related pancreatic peptide was approx. 95% pure as judged by HPLC and amino acid analyses. Glicentin-related pancreatic peptide has an isoelectric pH of 4.0 and consists of 30 amino acid residues (M r 3445) in the following sequence: The above sequence of glicentin-related pancreatic peptide is identical to glicentin 1−30 .

The secretion of glucagon by transformed yeast strains

Saccharomyces cerevisiae strains were transformed with plasmids coding for modified mating factor α1 leader sequences followed by glucagon. Glucagon‐containing peptides which were secreted into the fermentation broth were isolated and their amino acid sequences determined. The yeast strain transformed with the sequence coding for the complete mating factor α1 leader sequence preceding the glucagon gene (MT556) secreted glucagon plus glucagon extended at its N‐terminal by parts of the leader sequence. The yeast strain transformed with the sequence coding for a truncated mating factor α1 leader sequence before the glucagon gene (MT615) secreted glucagon. These observations suggest that S. cerevisiae is a suitable vehicle for the efficient expression of plasmids coding for polypeptides similar to glucagon (e.g. VIP, secretin, GIP).