Vezanje indolnih spojeva na ljudski albumin

Albumin (HSA) jedan je od najvažnijih transportnih proteina u ljudskom serumu. Albumin veže različite endogene i egzogene tvari. U patološkim stanjima kao što je zatajenje bubrega te u bolestima jetre, dolazi do nakupljanja uremičnih spojeva koji se vežu na albumin i na taj način inhibiraju vezanje lijekova pa terapija nije učinkovita. Jedan od uremičnih spojeva je indol-3-octena kiselina (IAA) za koju je dokazano da se specifično veže na albumin u patološkim stanjima. U ovom radu istraženo je vezanje IAA, L-triptofana, 5-metil-IAA i 5-benziloksi-IAA na HSA u prisustvu i odsustvu vezanih masnih kiselina koje se normalno u organizmu vežu na HSA. Metodom ravnotežne dijalize i fluorescencijske spektroskopije određena je koncentracija nevezanog i vezanog liganda te su podaci analizirani grafičkim prikazom prema Scatchardu. Indolni spojevi se vežu specifično na jedno vezno mjesto u albuminu s različitim afinitetima. Najveći afinitet ima IAA u odnosu na ostale proučavane indolne spojeve. Human serum albumin (HSA) is one of the most important transport proteins in human serum. Albumin binds various endogenous and exogenous substances. In pathological conditions such as renal failure and in liver disease, there are present uremic compounds which bind to albumin and thereby inhibit the binding of drugs leading to ineffective therapies. One of the uremic compounds is indole-3-acetic acid (IAA) which has been shown to specifically bind to albumin in pathological conditions. This study investigated the binding of IAA, L- tryptophan, 5-methyl-IAA and 5-benzyloxy-IAA to HSA in the absence and presence of fatty acids, which are normally bound to HSA. By using methods of equilibrium dialysis and fluorescence spectroscopy, the concentrations of unbound and bound ligands were determined, and the data were analyzed according to Scatchard plot. Indole compounds are binding specifically to one binding site of the albumin with different affinities. IAA binds with the highest affinity as compared to other studied indoles.