[Prokaryotic expression and hypoglycemic activity determination of insulin G1 from Conus geographus]

Rapid reduction of postprandial blood glucose is very beneficial to diabetics. In order to shorten the onset time of recombinant insulin, the cone snail insulin G1 (cI G1) of Conus geographus was studied. First, the nucleotide sequence of recombinant cone snail proinsulin G1 (cPI G1) was designed and synthesized according to the genes of human proinsulin (hPI) and cPI G1. The codon was optimized according to Escherichia coli (E. coli) codon usage frequency. Then, the plasmid pET22b(+)-cPI G1 was constructed and the recombinant cPI G1 was expressed in E. coli BL21(DE3) host strain. The recombinant cPI G1 was then purified and cleaved specially by trypsin to generate the recombinant cI G1, and its potency is 25.9 IU/mg. Fasting blood glucose test (FBGT) and oral glucose tolerance test (OGTT) suggested that the recombinant cI G1 could rapidly reduce blood glucose in normal and streptozotocin (STZ)-induced diabetic mice, but only for a short duration. This study provides a technical reference for the development of recombinant fast-acting insulin.