A hydrophobic tryptic peptide from bovine white matter proteolipid

A hydrophobic, chloroform-soluble tryptic peptide with a molecular weight of approximately 4000 has been purified from the bovine white matter proteolipid protein. Its primary structure was obtained by a combination of solid-phase Edman degradation and mass spectrometry. A major part of the tryptic peptide appears to be inaccessible to the action of proteolytic enzymes. The peptide spans the three cyanogen bromide peptides located by Jollès et al. (Biochem. Biophys. Res. Commun. (1979) 87, 619--626) at the COOH-terminal region of the intact protein. Secondary structure calculations for this region indicate a segregation into discrete domains, with most of the tryptic peptide corresponding to a highly ordered, hydrophobic domain; an equal probability for alpha-helical or beta-structure is predicted for this region.