Photo-isomerization and oxidation of bilirubin in mammals is dependent on albumin binding.

摘要: The bilirubin (BR) photo-conversion in the human body is a protein-dependent process; an effective photo-isomerization of potentially neurotoxic Z,Z-BR as well its oxidation to biliverdin antioxidant redox cycle possible only when BR bound on serum albumin. We present novel analytical concept study linear tetrapyrroles metabolic processes based in-depth mapping binding sites structure albumin (HSA). A combination fluorescence spectroscopy, circular dichroism (CD) and molecular modeling methods was used for recognition site BR, derivatives (mesobilirubin ditaurate), products (lumirubin, biliverdin, xanthobilirubic acid) HSA. CD spectra fluorescent quenching Trp-HSA were calculate constants. results displacement experiments performed with hemin interpreted together findings docking pigment-HSA complexes. estimated that bind two independent sites. Our support existence reversible explain additional pathway process (increase HSA capacity; excess free [unbound] can be converted also HSA).