Interaction Between Cibacron Blue F3GA and Luteinizing Hormone: A Chromatographic Investigation

Abstract

Luteinizing hormone which was bound to Cibacron Blue F3GA could not be eluted with 10mM NAD. Bound LH could be eluted partially (up to 5%) with 80% ethylene glycol and rest with 50mM phosphate buffer pH 7.5 containing 1M NaCl. Each of the bound fractions could also be sub-fractionated with differential elution with a gradient of ethylene glycol or NaCl. This indicated that pituitary LH was a mixture of two different sub-populations of LH, one which interacts with CB predominantly via hydrophobic interactions and the other via electrostatic interaction. In the case of subunits of LH that occur in free state in pituitaries, approximately half of the bound subunits interacted with CB column predominantly via hydrophobic interactions whereas the other half interacted via electrostatic force. It is concluded that differences in glycan content, composition and structure could be the cause for differential binding of buLH and its free subunits to the CBA column. 243 | P a g e luteinizing hormone. Results indicate that under appropriate conditions of elution, heterodimeric LH can be fractionated into different isoforms. It has also been shown here that the dye exhibits different binding preferences for the two free subunits (alpha and beta) of buLH.