THE STRUCTURE OF SYNENKEPHALIN (PRO-ENKEPHALIN(1-73)) IS DICTATED BY 3 DISULFIDE BRIDGES

Mass spectrometry of fragments produced by limited proteolytic digesti on of pro-enkephalin was used to locate the disulfide bridges in synen kephalin (pro-enkephalin 1-73), a domain which contains sorting inform ation for targeting the pro-neuropeptide to the granules of the regula ted secretory pathway in neuroendocrine cells. Mass spectrometric anal ysis was optimized by using chemicals that gave low interference with the ionization and desorption processes, and computer software which s implified the identification of all possible disulfide-linked peptide fragments. Three disulfide bridges between Cys(2)-Cys(24), Cys(6)-Cys( 28), and Cys(9)-Cys(41) were identified. Protein conformational predic tion of synenkephalin(1-42), shows beta-turns which facilitate the for mation of these disulfide bonds. (C) 1997 Academic Press.