Fragments of bovine serum albumin produced by limited proteolysis. Isolation and characterization of peptic fragments.

Five new fragments of bovine serum albumin have been isolated following limited peptic hydrolysis. These fragments, and the two peptic fragments previously described by King (King, T.P. (1973), Arch. Biochem. Biophys. 156, 509), were positioned within the albumin sequence published by Brown (Brown, J.R. (1975), Fed. Proc., Fed. Am. Soc. Exp. Biol. 34, 591) on the basis of molecular weight, amino acid composition, and amino- and carboxyl-terminal sequences. The fragments correspond to residues 1-385, 1-306, 307-581, 49-185, 186-306, 307-385, and 353-503 in the albumin sequence. These peptides are likely to be native in structure since disulfide bonds were not cleaved during their preparation. In each case the amino acid composition and terminal sequences have confirmed the bovine serum albumin sequence and disulfide bridging pattern proposed by Brown, and the offer further proof that bovine albumin is composed of a series of nine independent loops. These fragments should be useful in elucidating the structure-function relationships of albumin.