Median charge and charge heterogeneity of human pituitary FSH, LH and TSH. I. Zone electrophoresis in agarose suspension.

Abstract

The charge and charge heterogeneity of FSH, LH and TSH in 63 extracts of individual human pituitaries were investigated by use of zone electrophoresis in 0.17% agarose suspension in veronal buffer at pH 8.6 followed by hormone analyses by radioimmunoassay. The migration velocities are similar to those in free solution and directly proportional to differences in charge in the buffer. The technique gave highly reproducible results and the recovery of hormone activity after electrophoresis was about 100%. Methods for estimation of median charge, expressed as median migration rate, and of degree of charge heterogeneity are described. Each pituitary contained a sequence of different forms, estimated at 20 or more, of each of the three hormones, with minor differences in charge. The degree of charge heterogeneity within the pituitary was similar for FSH, LH and TSH. The distribution curves of radioimmunological activity in relation to migration rate were close to normality for the three glycoprotein hormones. This was in contrast to that found for Prl and GH. The merits of the electrophoretic technique are discussed.