The Amino-Acid Sequence of the Variable Region of a Carbohydrate-Containing Amyloid Fibril Protein EPS (Immunoglobulin Light Chain, Type λ)

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Abstract
The amino-acid sequence of the variable region of a carbohydrate-containing amyloid fibril protein EPS of Ig .lambda. light chain origin was elucidated. The protein was isolated from the liver of a patient (EPS) with an immunocyte dyscrasia of the IgM type. The molecular mass of this protein was found to be about 20 kDa [Kdalton] including an oligosaccharide chain linked to it. The amino-acid sequence determination involved automatic Edman degradation of polypeptides obtained after cleaving the protein with BNPS-skatole, trypsin and thermolysin. The proposed sequence of the variable region of the protein showed that it may be assigned to the V.lambda.I subgroup. A tryptic and a thermolysinolytic peptide both containing the carbohydrate were isolated and characterized, and the localization of an oligosaccharide chain linked to asparagine was established.