An acrylamide gel recombination assay for glycoprotein hormone subunits

A specific and sensitive assay for recombination of the subunits of hCG and other glycoprotein hormones (LH, FSH, and TSH) is presented. The assay depends on the ability of sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE) to separate clearly the subunits from native hormone. Iodinated subunit is incubated with its identical unlabeled subunit and complementary subunit. Quantitative displacement of the radioactivity to the native hormone position as followed by gel slicing is used as a direct index of recombination. The assay is reproducible, sensitive to less than one picomole of hormone formed, and offers a simple means of evaluating recombination of glycoprotein chains as distinct from biological activity.