Processing of the spectrofluorimetric data using the graphical methods and the maximum likelihood approach

The present work describes the calculation of the binding constants from spectrofluorimetric data using simple graphical methods and specialized software implementing the maximum likelihood approach. The following popular cases are analyzed: 1) protein-small molecule; 2) protein-metal complex; 3) DNA-small molecule; 4) DNA-metal complex interactions. The inability of graphical plots to return the correct results except for the simplest situation (single reaction with a non-fluorescent product) is demonstrated. The possibility of determining the most probable stoichiometric model using the maximum likelihood estimation (LSQ as its special case) is discussed as well as the limitations.

Binding of pyridoxal, pyridoxal 5'-phosphate and derived hydrazones to bovine serum albumin in aqueous solution

In the present paper, the kinetics of a reaction between bovine serum albumin (BSA) and pyridoxal, pyridoxal 5'-phosphate was studied, apparent rate constant of product formation and dissociation as well as binding constants were determined. Pyridoxal 5'-phosphate hydrazones of isonicotinic, picolinic, 2-furoic, thiophene-2-carboxylic, pyrazinoic acids binding to BSA was studied by spectrofluorimetry, stability constants of the associates were calculated from experimental data using maximal likelihood approach. The changes in the secondary structure of BSA induced by hydrazones addition were studied by IR spectroscopy. New freely available software for curve fitting was developed as a part of the software kit designed for the solution chemistry and used for a specific problem of this study, IR spectra processing.