PURIFICATION OF A RECOMBINANT GFP-PREPTIN FUSION PROTEIN**

Abstract

Preptin is a 34 residue peptide hormone, extracted from secretory granules of pancreatic β cells. It has demonstrated promise as a therapy for two common diseases: osteoporosis and diabetes. The study aims to delve deeper into the metabolic pathway of preptin. The secondary structure and metabolic mechanism of preptin remain unknown. To begin to understand the metabolic capaabilities of preptin, we are pursing a structure-activity relationship (SAR) study of the peptide via alanine scanning mutagenesis. The following preptin residues were all singly mutated to alanine and analogs were expressed as green fluorescent fusion proteins in E. coli: P17A, V18A, G19A, W27A, R28A, Q29A. Currently, we are optimizing purification of the fusion protein in preparation of site-specific cleavage and isolation of the mutated analogs. By studying the effects of these mutations, we aim to determine which amino acids in preptin\u27s primary structure are vital to its metabolic activity