ISSN:
1573-904X
Keywords:
nicotinic acid esters
;
carboxylesterases
;
subcellular fractions
;
structure–metabolism relationships
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract Rat liver and brain subcellular esterase activities toward nicotinic acid esters were studied, under varying conditions, such as pH, organic solvents, protein concentration, duration of incubation, and substrate concentration. Esterases in each subcellular fraction displayed activities that obey Michaelis–Menten kinetics, although subcellular fractions are heterogeneous. The K m values were of the same magnitude, and the V max values were lower in microsomes than in cytosol of the liver. Brain activities normalized to protein concentration, were much lower than liver activities, aromatic nicotinates being the best substrates in both tissues. Myelin and brain mitochondria of nerve-ending and neuroglial origin display esterase activity toward phenyl nicotinate. In contrast to brain esterases, liver esterases appear homogeneous, and esterase activities in both tissues react differently to changes in pH. Qualitative and quantitative structure–metabolism relationships are not suggestive of tissue-specific ester hydrolysis.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1015839109449
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