Determination of kinetic parameters for 3α-hydroxysteroid dehydrogenase using the five major bile acids and their conjugates as substrates and correlation with their structure and solubility

Abstract

Kinetic parameters for 3α-hydroxysteroid dehydrogenase (3α-HSD) using the five major free bile acids and their glycine and taurine conjugates as substrates and β-nicotinamide adenine dinucleotide (β-NAD⁺) as coenzyme were determined from initial rate measurements. Four different mathematical methods were used for the evaluation of the results: (a) the double reciprocal plot, (b) the direct linear plot, (c) the Woolf plot and (d) the Scatchard plot methods. The determined kinetic parameters were correlated with the structure of the substrates (number of free hydroxy groups) and their absolute aqueous solubilities.