5 - Chemistry of Human Chorionic Gonadotropin

Abstract

This chapter discusses the chemistry of human chorionic gonadotropin (HCG), and its relation to luteinizing hormone (LH) and interstitial cell-stimulating hormone (ICSH). HCG is produced by the placenta during pregnancy. In the first trimester of pregnancy, the synthesis of the hormone reaches its maximum level, as determined in the urine or blood. HCG belongs to the general class of glycoprotein hormones. In this class are also included, among others, follicle stimulating hormone (FSH) and thyrotropin (TSH). With the exception of TSH, all of them are involved in the biochemistry of reproduction. Methods of purification of HCG essentially involve two steps: (1) extraction of HCG from the urine, and (2) purification of the crude extract. Conventional methods of protein purification that have improved considerably in the past few years have been employed for the purification of HCG from the crude extract. HCG consists of two dissimilar subunits α and β, both of which are required for its biological activity.