Biology Department, Brookhaven National Laboratory, Upton, New York 11973 U.S.A.
Abstract:
The amino acid sequence of human pancreatic secretory trypsin inhibitor Pubols, M. H., Bartelt, D. C., and Greene, L. J. (1974) J. Biol. Chem., 249, 2235–2242] was determined by a combination of selective trypsin and chymotrypsin hydrolysis reactions on the S-2-aminoethylcysteinyl inhibitor and conventional methods (subtractive Edman degradation and exopeptidase hydrolysis) for sequence determination of small peptides. The peptides were ordered on the basis of the identification of the amino- and carboxyterminal residues of the products at each stage of the degradation procedure. The sequence determination was carried out on a mixture of chromatographic forms present in both tissue and pancreatic juice which are identical in amino acid composition, aminoterminal residues, molecular weight, and specific activity, but differ only in asparagine content and susceptibility to enzymatic hydrolysis. The amino acid sequence of the human inhibitor corresponding to chromatographic form A3 has been shown to be NH2
