Specific binding of 125I-labeled human chorionic gonadotropin to gonadal tissue: comparison of limited-point saturation analyses to Scatchard analyses for determining binding capacities and factors affecting estimates of binding capacity.

Experiments were conducted to compare gonadotropin binding capacity calculated from limited-point saturation analyses to those obtained from Scatchard analyses, and to test the effects of membrane purity and source of gonadotropin receptors on determining the maximum percentage of radioiodinated hormone bound to receptors (maximum bindability). One- to four-point saturation analyses gave results comparable to results by Scatchard analyses when examining relative binding capacities of receptors. Crude testicular homogenates had lower estimates of maximum bindability of 125I-labeled human chorionic gonadotropin than more purified gonadotropin receptor preparations. Under similar preparation techniques, some gonadotropin receptor sources exhibited low maximum bindability.