Apyrase

Apyrase

Apyrase is a calcium-activated plasma membrane-bound enzyme (magnesium can also activate it) (EC number|3.6.1.5) that catalyses the hydrolysis of ATP to yield AMP and inorganic phosphate. Two isoenzymes are found in commercial preparations from "S. tuberosum". One with a higher ratio of substrate selectivity for ATP:ADP (approx 10) and another with no selectivity (ratio 1).

It can also act on ADP and other nucleoside triphosphates and diphosphates with the general reaction being NTP -> NDP + Pi -> NMP + 2Pi.

It is the enzyme released by female mosquitoes to prevent blood clots when they suck blood.

The activity of apyrase at pH 7.5 in a Tris Buffer is approximately 80% of the activity at pH 6.5.

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