Topic
Esterase
About: Esterase is a research topic. Over the lifetime, 7622 publications have been published within this topic receiving 168270 citations.
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TL;DR: Studies on the subcellular distribution of tryptase TL2, immunohistochemical analysis, and cell surface radioiodination indicated that the enzyme is mainly localized in the plasma membrane.
69 citations
TL;DR: Inhibitor studies conducted with protein extracts prepared from dried overground parts of E. purpurea revealed that polyphenol oxidases but not peroxidases are responsible for the oxidative degradation of exogenous and endogenous caffeic acid derivatives.
Abstract: Cichoric acid (2R,3R-O-dicaffeoyltartaric acid) (1) is highly susceptible to enzymatic degradation during the preparation of Echinacea purpurea products. Degradation of 1 and other caffeic acid derivatives can be inhibited by antioxidants added to the extraction solvent or in buffered protein extracts saturated with nitrogen. Inhibitor studies conducted with protein extracts prepared from dried overground parts of E. purpurea revealed that polyphenol oxidases (PPO) but not peroxidases are responsible for the oxidative degradation of exogenous and endogenous caffeic acid derivatives. With a view to stabilizing aqueous extracts with respect to their content of 1, the effects of ascorbic acid and ethanol were tested. Compound 1 was not stable under conditions where oxidative processes could almost be excluded. It was found that an esterase hydrolyzing the ester bonds between tartaric acid and caffeic acid is still active under PPO inhibitory conditions. Finally, addition of 40% ethanol and 50 mM ascorbic acid to aqueous extracts of "Echinaceae purpureae herba" resulted in a constant amount of cichoric acid over four weeks.
69 citations
TL;DR: Embryogenic callus and suspension cultures secreted a musilagenous polysaccharide whose production was stimulated by 2,4-dichlorophenoxyacetic acid and may be related to the ‘cementing layer’ in maize kernels.
69 citations
TL;DR: The results of a comparison of the actions of individual human sera support evidence previously obtained for the existence of two different types of pseudocholinesterase in man.
Abstract: The results of a comparison of the actions of individual human sera support evidence previously obtained for the existence of two different types of pseudocholinesterase in man. Maximum rates of hydrolysis of choline esters by human sera containing the normal type of cholinesterase were two to four times greater than the maximum rates obtained with sera containing atypical esterase. Human sera with the normal type of cholinesterase hydrolyzed butyrylcholine at a considerably faster rate than pentanoylcholine; atypical esterase hydrolyzed pentanoylcholine at approximately the same rate as butyrylcholine. All Michaelis constants for the normal enzyme were lower than those for the atypical enzyme by a factor which varied from 1.4 to 6.4. The data were compatible with the assumption of a linear relationship between the log of the Michaelis constants and the number of acyl carbons in the choline esters, but the slopes differed significantly for the two enzymes. For a homologous series of choline esters, there ...
69 citations
TL;DR: The reaction of mercuripapain with glutaraldehyde resulted in an insoluble enzymes that possessed, after treatment with cysteine, approximately twice as much esterase and proteinase activities as did the insoluble enzyme prepared from papain.
69 citations