EFFECT OF pH ON THE BINDING OF THYROXINE TO SERUM PROTEINS

Abstract

ABSTRACT The maximal binding capacity of human thyroxine-binding globulin (TBG) was found to decrease, and that of thyroxine-binding pre-albumin (TBPA) to increase with an increase in pH in the range of pH 7.2 to 8.2. On the other hand, the transfer of T4125I from the serum to a weak binder (Sephadex) was found to decrease with increasing pH. The same phenomena was shown to exist in mouse and rat serum, and to be blocked by DNP, a potent TBA & TBPA binding inhibitor. It is suggested that serum albumin may play a pH sensitive role in the T4 transfer to tissue.