Electronic Resource
Oxford, UK
:
Blackwell Publishing Ltd
Journal of neurochemistry
27 (1976), S. 0
ISSN:
1471-4159
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Medicine
Notes:
Abstract– The properties of histidine decarboxylase (l-histidine carboxylyase EC 4.1,1.22) have been studied in a whole rat brain homogenate. Optimum pH depended upon substrate concentration; the variations of Km and Vmax were determined as a function of pH. pH values lower than 6.0 caused a loss of enzymic activity; activity was stable at pH values higher than 6.0. Enzyme activity was proportional to temperature in the range 30-45°C; temperature characteristic (μ) and Q10 were determined and thermal inactivation was studied. Addition of pyridoxal 5′-phosphate increased enzyme activity. Dialysis of homogenates against phosphate buffer caused a partial loss of enzyme activity which could be restored by addition of the coenzyme to the incubation mixture. Enzyme activity was inhibited by α-methylhistidine and benzene and was unaffected by α-methyl DOPA. The properties correspond to those of a ‘specific’ histidine decarboxylase. However, the brain enzyme differs from the corresponding enzyme in peripheral tissues in the inability to achieve a total inhibition of activity by dialysis.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1471-4159.1976.tb02629.x
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