q-Albumin: HSA binding prediction software.

Drug distribution within the body is determined mainly by free (unbound) concentration of drug in circulating plasma. The unbound fraction, in turn, depends on drug absorption by plasma proteins. Human Serum Albumin (HSA) is the most abundant blood plasma protein and is produced in the liver.

q-Albumin software takes a molecular structure and calculates HSA binding constant by docking the molecule to both of the HSA active sites (Sudlow site I and Sudlow site II). The results of the calculation for a number of drugs with known binding constants are represented on the Figure above: see improvement of the correlation by using flexible protein model (red dots) over the docking on a rigid protein structure from PDB (blue dots).

Binding affinity calculation of known drugs to human serum albumin