The Isolation and Partial Purification of a Non-Parathyroid Hormone Calcemic Fraction from Bovine Parathyroid Glands

Abstract

The isolation and partial purification of a new calcemic material found in bovine parathyroid glands is described. This material, designated calcemic fraction-A, is different from parathyroid hormone but possesses on a weight basis approximately one-half to one-third the biological activity of parathyroid hormone in both in vivo and in vitro test systems. The biosynthesis of calcemic fraction-A, studied in an in vitro incubation system, was inhibited by high concentrations of calcium in the incubation medium. Analysis of calcemic fraction-A by radioimmunoassay indicated it to be immunoreactive with anti-parathyroid hormone antiserum in a fashion identical to authentic parathyroid hormone but with lower potency. Based on gel filtration it appears to be larger in size than parathyroid hormone. (Endocrinology89: 1440, 1971)