Importance of sodium dodecyl sulfate source to electrophoretic separations of thylakoid polypeptides

Electrophoretic banding patterns of Chlamydomonas reinhardtii thylakoid polypeptides differ depending on whether impure, or pure sodium dodecyl sulfate (SDS) is used. Bands of M r 45,000 and 36,000 were found when impure sodium dodecyl sulfate was used, but the M r 45,000 band was absent when pure sodium dodecyl sulfate was used. Seven thylakoid polypeptides were isolated using preparative polyacrylamide gel electrophoresis, and the pure sodium dodecyl sulfate. Polypeptide ( M r 36,000) reran as a single band in pure sodium dodecyl sulfate, but yielded M r 45,000 and 36,000 bands in impure sodium dodecyl sulfate. Although the R f of most of the six other polypeptides differed, depending on whether pure or impure sodium dodecyl sulfate was used, the M r of these polypeptides was the same with both. Thus, the banding pattern difference due to SDS source results from differences in R f without changes in apparent M r and a marked change in M r of one polypeptide.