[Molecular bases of the fluorescence method in the determination of binding capacity of serum albumin].

A fluorescent method for assessment of albumin capacity to bind low-molecular metabolites, toxins, or drugs in blood serum, making use of fluorescent probe K-35, was recently suggested. The paper presents results of investigation of molecular basis of the method and of principles of interaction between fluorescent test molecules with albumin molecules in the blood serum. Molecules of fluorescent probe K-35 in blood serum plasma or serum are binding to albumin centers transporting low-molecular ligands (metabolites, toxins, drugs, etc.). Virtually the total intensity of K-35 fluorescence is due to the very molecules of the probe which are situated in these albumin centers. K-35 occupies two types of albumin centers, both of them equally contributing to total fluorescence intensity. Appearance of metabolites filling albumin centers and competing with K-35 probe results in reduction of the probe fluorescence. It is observed both in simulation experiments and in disease. It is possible that, besides the competitive mechanism, other mechanisms of blocking albumin centers in disease exist, to which K-35 is similarly sensitive. K-35 probe may be also used to measure effective albumin concentration.