nitrophenols and 2-naphthylacetic-acid

Ester precursors of fluorogenic or chromogenic probes are often employed in studies of yeast cell biology. This study was aimed at a comparison of the ability of several commonly used laboratory wild-type Saccharomyces cerevisiae strains to hydrolyse the following model esters: fluorescein diacetate, 2-naphthyl acetate, PNPA (p-nitrophenyl acetate) and AMQI (7-acetoxy-1-methylquinolinum iodide). In all the strains, the esterase activity was localized mainly to the cytosol. Considerable differences in esterase activity were observed between various wild-type laboratory yeast strains. The phase of growth also contributed to the variation in esterase activity of the yeast. This diversity implies the need for caution in using intracellularly hydrolysed probes for a comparison of yeast strains with various genetic backgrounds.

Topics: Cell Size; Cytosol; Esterases; Esters; Fluoresceins; Hydrolysis; Naphthaleneacetic Acids; Nitrophenols; Saccharomyces cerevisiae; Species Specificity; Substrate Specificity

The hydrolysis of paraoxon (POX), phenylacetate (PA) and beta-naphthylacetate (BNA) was studied in human serum. Based upon correlations between enzyme activities, upon reversible inhibition by EDTA and upon progressive inhibition by iso-OMPA, tabun, eserine and bis-4 nitrophenylphosphate, the following conclusions were drawn about the number and specificity of enzymes involved in the hydrolysis. Two paraxonases hydrolyse paraoxon: one sensitive and the other insensitive to EDTA. The EDTA-sensitive paraoxonase also hydrolysed BNA. The EDTA-insensitive hydrolysis of BNA and PA was attributed to a serine esterase. The EDTA-sensitive hydrolysis of PA is probably due to more than one enzyme, which might be an arylesterase and a carboxylesterase.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Aryldialkylphosphatase; Cholinesterase Inhibitors; Cholinesterases; Edetic Acid; Esterases; Female; Humans; Hydrolysis; Kinetics; Male; Middle Aged; Naphthaleneacetic Acids; Nitrophenols; Organophosphates; Organophosphorus Compounds; Paraoxon; Phenylacetates; Phosphoric Monoester Hydrolases; Physostigmine; Sensitivity and Specificity; Substrate Specificity; Tetraisopropylpyrophosphamide; Thiocholine