Analysis of Computer-Generated Hydropathy Profiles for Human Glycoprotein and Lactogenic Hormones*

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Abstract
Analysis of hydrophobic and hydrophilic regions of human lactogenic (PRL [prolactin] GH [growth hormone] and placental lactogen) and glycoprotein hormones (FSH, LH [luteinizing hormone], TSH, and hCG [human chorionic gonadotropin]) by the method of Kyte and Doolittle has been performed. A BASIC program, developed for the IBM personal computer, produces graphical and tabular results. The net hydropathy value, a new parameter based on the Kyte and Doolittle analysis which may be useful for comparing various polypeptides, was developed. This value is correlated with physical properties, such as solubility of the glycoprotein hormones. New (more hydrophilic) indices were assigned for glycosylated asparagine, serine and threonine residues, and slightly more hydrophilic indices were assigned for half-cystines found in disulfide bonds. The so-called determinant loop of Ward and Moore is hydrophilic (accessible), and regions on either side of this loop should also be considered as potential effectors of hormone specificity. Binding (protein-protein interaction) sites tend to be modestly hydrophilic, but also contain residues that could interact through the hydrophobic effect.