SPECTROSCOPIC CHARACTERIZATIONS OF ALPHA FETO PROTEINBINDING WITH ITS ANTIBODY BY IRMA METHOD IN TISSUE’SHOMOGENATE OF SOME TYPES OF OVARIAN TUMORS

Abstract

Spectroscopic studies, in the ultraviolet region were carried out to characterize the
binding of isolated AFP with its labeled antibody in human malignant germ cell ovarian
tumor homogenates. Factors affecting the absorption properties of AFP, and the complex
of isolated AFP with the labeled antibody such as pH, solvent polarity (solvent
perturbation technique), spectrophotometric pH titration and thermal stability in the
presence of different concentration of sodium chloride have been studied. The
spectroscopic pH titration curves for human AFP and for the complex of isolated AFP
with the labeled antibody gave pka of 5.7 and 7.3 for histidine residue, respectively,
while 11.6 and 11.4 for tyrosine residue, respectively. Furthermore the study showed
that 23.8% of histidine and 70.4 % of tyrosine residue are located on the surface of
human AFP antigen, while these residues were located 38.0% and 31.0% on the surface
of complex of the isolated AFP form.