Specificity of esterases. IV. Behavior of horse liver esterase towards a homologous series of n-fatty acid esters.

E’nxymes-(1) Purified horse liver esterase, prepared as described previously (2); (2) a crude extract of horse liver acetone powder, obtained by stirring the powder for several hours with a 2.5 per cent sodium acetate solution (3) followed by centrifugation. Substrates-These were esters of n-fatty acids and m-hydroxybenzoic acid, prepared by the same procedures as given previously (4, 1) for the corresponding ortho compounds. The starting materials were obtained commercially with the exception of undecanoic acid, which was supplied by the courtesy of Dr. L. Reiner of Wallace and Tiernan Products, Inc. The compounds were recrystallized until they were free from unchanged mhydroxybensoic acid (2), and constant melting points were obtained. The melting points (see tabulation) show an oscillation between odd and even numbered carbon chains over the entire series. It may be noted that they are somewhat higher than those of the corresponding ortho compounds (1). Additional checks on purity were made by complete hydrolysis in 0.1 N alkali and subsequent spectrophotometric determination (2) of m-hydroxybenzoic acid. The results, compared to the calculated amounts (per cent), are recorded in the following table.