Date of Award

2015

Degree Name

Chemistry

College

College of Science

Type of Degree

M.S.

Document Type

Thesis

First Advisor

Leslie Frost

Second Advisor

John Hubbard

Third Advisor

Bin Wang

Abstract

The C-peptide of insulin was thought to be biologically inactive, but recent studies have shown that the C-peptide causes multiple molecular and physiological effects. Evidence has shown that C-peptide binds to a cell surface receptor, probably a G-protein coupled receptor, and that the COOH-terminal pentapeptide is essential for binding and constitutes an active site. For a further understanding of the detailed nature of the physiological effects of C-peptide, the receptor structure needs to be determined. We designed an affinity column using C-peptide to try and gain a better understanding of the biological effects by examining what proteins the affinity column with attached C-peptide would isolate from bovine tissue samples. Since the C-peptide was shown to be internalized in the cytosol and nucleus of kidney cells, we started with cytoplasmic and nuclear tissue lysates obtained from bovine kidney tissue. The isolated proteins were eluted from the beads, and separated by reducing SDS-PAGE. Protein bands of interest were then excised from the gel, digested with trypsin, and analyzed via MALDI-TOF mass spectrometry. We were able to identify a couple of proteins using bovine heart tissue lysates isolated with C-peptide affinity beads. Fatty acid synthase and fatty acyl-CoA ligase were identified. The isolation of both fatty acid synthase and long chain fatty acyl-CoA ligase indicates that C-peptide may play a role in stimulating the production of fatty acids from excess glucose and converting those fatty acids to triacylglycerides for storage inside muscle cells. Our results indicate that C-peptide may be involved in modulating lipid metabolism within cells and may play a role in determining the fate of the excess glucose that enters cells by stimulating the production of fatty acids and conversion of those fatty acids to triacylglycerides for short-term intracellular storage instead of sending the fatty acids to the adipose tissue for long-term storage.

Subject(s)

C-peptide -- Research.

Insulin -- Research.

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