The Chemistry of Human Chorionic Somatomammotropin**Abbreviations used: HCS, human chorionic somatomammotropin; HGH, human pituitary growth hormone; BGH, bovine pituitary growth hormone; SGH, sheep pituitary growth hormone; o-PRL, ovine pituitary prolactin; 2-CAM-HCS, partially reduced-carbamidomethylated HCS; 4-CAM-HCS, totally reduced-carbamidomethylated HCS; 2-CXY-HCS, partially reduced-carboxymethylated HCS; 4-CXY-HCS, totally reduced-carboxymethylated HCS; NPS-HCS, the derivative formed by reacting HCS with o-nitrophenylsulfenyl chloride; PFOX-HCS, performic acid-oxidized HCS; NO2-HCS and NO2-HGS, the nitrated products formed by treating HCS or HGH with tetranitromethane; ACTH, pituitary adrenocorticotropic hormone; MSH, pituitary melanocyte stimulating hormone; LPH, pituitary lipotropin; HCG, human chorionic gonadotropin; hPr, human pituitary lactogenic hormone; DTT, dithiothreitol; CD, circular dichroism; the usual three letter abbreviations are used for amino acids.