ABSTRACT
Somatostatin was chosen for the pilot study because of its small size and the availability of good radioimmunoassays for its detection. In 1977, a chemically synthesized somatostatin gene was made, introduced into bacteria, and shown to function. Somatostatin was cleaved from the fused protein product by treatment in vitro with cyanogen bromide, which very specifically and efficiently cleaves polypeptide chains at methionine. Because the gene was made synthetically, it was easy to arrange for a methionine to be at the junction of beta-galactosidase and somatostatin. A common misconception is that human genes for human insulin were placed in bacteria and made to function. The laboratory demonstration of the bacterial production of human insulin was only the beginning of the difficult process of bringing human insulin to the public. Sulfonated derivatives of the insulin chains were made before purification to ensure stability by preventing the premature formation of disulfide bonds.
