| Abstrakt: |
The hexokinase activity of the seminal vesicle mucosa of the guinea-pig at 37° C. is equivalent to 0-1 mM glucose per gm. tissue per hour, and 0-07 mM fructose per gm. tissue per hour, at pH 7-2 with hexose concentrations of 0-003 M (60 mg. p.c). The Michaelis constants are glucose 4x10-5 M, fructose 2X10-3 M. In the presence of glucose, fructose phosphorylation is very slight. Phosphohexoisomerase activity is equivalent to 4 mM per gm. tissue per hour, with a substrate of glucose-6-phosphate. There are two phosphatases in the gland. An alkaline phosphatase, with optimum pH about 9-4, acting slightly faster on fructose-6-phosphate than on glucose-6-phosphate, is localized at the free border of the cell and seems to sediment in the microsome fraction of the cell. An acid phosphatase, optimum pH about 5-8, acts 10 times as rapidly on fructose-6-phosphate as on glucose-6-phosphate. It is generally distributed throughout the cell, and sediments in the highest concentration in the mitochondrial fraction of the cell. At pH 7, about 70 p.c. of the phosphatase activity is due to the alkaline phosphatase. The liberation of fructose is caused by the (relatively) nonspecific phosphatase, and the glucose simultaneously liberated is reutilized. This is made possible by the hexokinase, which will not affect fructose in the presence of glucose. [ABSTRACT FROM AUTHOR] |
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