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AMINO‐ AND CARBOXYL‐TERMINAL AMINO ACIDS OF PROTEOLIPID PROTEINS 1
Author(s) -
Whikehart D. R.,
Lees Marjorie B.
Publication year - 1973
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1973.tb00242.x
Subject(s) - amino acid , biochemistry , glycine , asparagine , glutamine , phenylalanine , aspartic acid , glutamic acid , carboxypeptidase , lysine , chemistry , biology , enzyme
Abstract The amino‐ and carboxyl‐terminal amino acids of proteolipids from neural and non‐neural sources were investigated. Amino‐terminal amino acids were identified and quantitated by the dansyiation procedure. Carboxyl‐terminal amino acids were determined after hydrazinolysis or enzymatic hydrolysis with carboxypeptidases. Proteolipid from white matter showed two terminal amino acids, regardless of the method of preparation. The major N‐terminal amino acid was glycine and the minor one was glutamic acid or glutamine. The corresponding C‐terminal amino acids were phenylalanine and glycine. Preparations of white matter proteolipid, therefore, contained more than one protein or protein chain. Proteolipids from brain mitochondria, heart, liver and kidney were characterized by N‐terminal aspartic acid or asparagine and C‐terminal lysine residues and they exhibited an amino acid composition which differed from white matter proteolipid. Our results suggest the existence of two classes of proteolipids, a myelin type and a non‐myelin type. Synaptic membrane and grey matter proteolipids exhibited characteristics of both classes.