title: Esterification of J chain and its effect on electrophoretic mobility in sodium dodecyl sulfate polyacrylamide gels.
abstract: Sodium dodecyl sulfate polyacrylamide gel electrophoresis yields mobilities indicative of molecular weights of approximately 27 000 for human J chain and approximately 14 000 for nurse shark J chain, in contrast to values of approximately 15 500 and approximately 12 200, respectively, obtained by other methods. The relatively high content of acidic amino acids of human J chain as compared to nurse shark J chain suggested that the greater error in the sodium dodecyl sulfate determined molecular weight for human J chain may be due to a charge anomaly. The overall net negative charge on human J chain was decreased by forming methyl esters of the carboxyl groups, resulting in a sodium dodecyl sulfate determined molecular weight of approximately 17 700. Methylated nurse shark J chain did not show a significant difference in sodium dodecyl sulfate electrophoretic mobility from the non-methylated form. These results form the basis for a possible explanation of an occasional artifact in a widely used analytical method.
mesh_terms: D000818:Animals; D055598:Chemical Phenomena; D002621:Chemistry; D004591:Electrophoresis, Polyacrylamide Gel; D004952:Esters; D007144:Immunoglobulin J-Chains; D007075:Immunoglobulin M; D008970:Molecular Weight; D012754:Sharks; D012967:Sodium Dodecyl Sulfate; D014508:Urea
chemical_list: D004952:Esters; D007144:Immunoglobulin J-Chains; D007075:Immunoglobulin M; D012967:Sodium Dodecyl Sulfate; D014508:Urea