Studies on Solid-Phase Peptide Synthesis: The Synthesis of Glucagon

Author

Svetlana Mojsov

Date of Award

1978

Document Type

Thesis

Degree Name

Doctor of Philosophy (PhD)

Thesis Advisor

Bruce Merrifield

Related Theses

View more theses from the Bruce Merrifield Laboratory

Keywords

synthetic glucagon, peptide synthesis, Bpoc protection, trifluoracetic acid, solid-phase strategy, hypoglycemic effect

Abstract

The feasibility of the stepwise-solid phase approach was studied in the synthesis of the peptide hormone glucagon. The choice of this molecule was based upon: (1) the unusual chemical structure; (2) biological significance. The main features of the strategy employed are: (1) the use of Biphenylisopropyloxycarbonyl group (Bpoc) for N^α-amino protection; (2) the use of t-butyl based protecting groups for side chains of the trifunctional amino acids; and (3) the use of E-alkoxybenzyl-alcohol-resin as a solid support. At each step of the synthesis the N^α-Bpoc moiety was removed by treatment with 0.5% trifluoracetic acid in dichloromethane. Deprotection of most of the side-chain protecting groups as well as cleavage of the peptide from the resin at the end of the synthesis was accomplished through treatment of the protected peptide resin with 50% TFA in dichloromethane in the presence of carbonium ion scavengers. The crude synthetic glucagon was purified by gel filtration and ion exchange chromatography. The pure synthetic glucagon was isolated in 5.4% overall yield based upon the amount of the first amino acid anchored to the resin. The similarity between synthetic and natural glucagon was demonstrated through the use of amino acid analyses, ultraviolet absorption and fluorescence spectrometry, polyacrylamide gel electrophoreses, gel filtration and ion exchange chromatograms. Additionally, the synthetic material was isolated as crystalline rhombic dodecahedra. Injection of rabbits with three different dosages of synthetic glucagon did cause a rise in the blood sugar levels. Within the limits of the bioassay, the maximal hypeglycemic effect was indistinguishable from that caused by native glucagon itself.

Comments

A thesis presented to the faculty of The Rockefeller University in partial fulfillment of the requirements for the degree of Doctor of Philosophy

License and Reuse Information

This work is licensed under a Creative Commons Attribution-NonCommercial-Share Alike 4.0 International License.

Recommended Citation

Mojsov, Svetlana, "Studies on Solid-Phase Peptide Synthesis: The Synthesis of Glucagon" (1978). Student Theses and Dissertations. 474.
https://digitalcommons.rockefeller.edu/student_theses_and_dissertations/474