It is planned to apply the amino acid sequencing technique developed during the past years of this grant to naturally occurring oligopeptides ranging from 25 to 90 amino acids. Major efforts will be devoted to the development of a more automatic identification procedure for the components of the peptide mixture as well as reassembly to the original sequence. In the area of wet chemistry, experiments will be continued to increase the yield in the various chemical and extractive steps to make it possible to successfully handle smaller and smaller amounts of an individual protein derived peptide. Major emphasis will be on the decrease of the number of individual steps and transfers, effect of purity of reagents, minimization of reagents, etc. Bibliographic references: The Amino Acid Sequence of a Carboxypeptidase Inhibitor from Potatoes, G.M. Hass, H. Nau, K. Biemann, D.T. Grahn, L.H. Ericsson, and H. Neurath, Biochemistry 14, 1334 (1975). Polypeptide Sequencing by a Gas Chromatograph-Mass Spectrometer-Computer System. Generation and Derivatization of Complex Mixtures of Oligopeptides, J.A. Kelley, H. Nau, H.-J. Forster, and K. Biemann, Biomed. Mass Spectrom., in press.