Structural Studies on the P2 Protein in Bovine Peripheral Nerve Myelin

The complete amino acid sequence of the P2 protein in bovine peripheral nerve myelin was determined and its structural characteristics were studied.Bovine P2 protein consists of 131 amino acid residues with a calculated molecular weight of 14,859 daltons, containing 2 mol of tryptophan, 3 mol of methionine, 2 mol of halfcystine with an intramolecular disulfide bond, and the blocked N-terminus, acetylserine.The over-all sequence reveals no obvious periodicity but rather a general distribution of charged residues over the polypeptide chain.On the basis of Chou and Fasman's prediction of secondary structure, the P2 protein is thought to contain a high degree of [3-structure.When the primary structure of bovine P2 protein is compared with the known sequences of rabbit and human P2 proteins, several substitutions are found: four substitutions in the 65 N-terminal residues of rabbit P2 protein and six substitutions in the 77 C-terminal residues of human P2 protein.Possible antigenic determinants of experimental allergic neuritis are discussed from a structural point of view.