FLUORESCENCE KINETICS OF COMPLEX FORMATION BETWEEN HUMAN SERUM ALBUMIN AND ZINC-PHTHALOCYANINE TETRASULFONIC ACID

Stopped-flow fluorescence was employed to measure the dissociation constant, activation energy, and frequency factor for zinc phthalocyanine tetrasulfonic acid binding to human serum albumin. A pseudo 1^st order "Isolation Method" was used to measure temperature dependent rate constants at pH 7.00. Binding was followed by a relatively large emission signal that indicated the formation of a protein-ligand complex. The dissociation constant, activation energy and frequency factor were 3.3 (±0.3)×10^-5 (M), 4.5 (±0.2)×10⁴ J/mol, and 1.1 (±0.1)×10⁸ min^-1 respectively.