Open AccessPROPERTIES OF HALVES OF IMMUNOGLOBULIN LIGHT CHAINS
Author(s) -
F. Anders Karlsson,
Per A. Peterson,
Ingemar Berggärd
Publication year - 1969
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.64.4.1257
Subject(s) - immunoglobulin light chain , proteolysis , bence jones protein , papain , chemistry , stokes radius , trypsin , electrophoresis , urea , biochemistry , globular protein , crystallography , antibody , biology , size exclusion chromatography , enzyme , immunology
Light polypeptide chains from both normal human γG immunoglobulin and Bence-Jones proteins can be cleaved into halves by limited proteolysis with trypsin, pepsin, or papain. The fragments were obtained in yields of up to 22 per cent, had molecular weights of 10,000 to 11,000, and were shown by amino acid analysis and antigenic analysis to correspond to variable or constant regions of light chains. Starch gel electrophoresis in urea suggested that each half consisted of a single polypeptide chain. A fragment from the urine of a myeloma patient corresponded almost exactly to the constant half of a γ-chain and had a compact shape (Stokes radius of 16 Å; frictional ratio of 1.1). Similar Stokes radii were estimated both on fragments from normal urine and fragments produced by proteolysis of normal light chains. The results are consistent with the view that most urinary fragments have a catabolic origin and suggest that there is a small stretch of polypeptide chain between the compact V and C regions of light chains which is particularly susceptible to proteolysis. This lends support to the hypothesis that immunoglobulin chains consist of globular domains connected by more extended stretches of polypeptide chain.