Abstract
In the tissue of silkworm the existence of an inhibitor of biological nitrate reduction has been demonstrated. This substance is heat-resistant and cannot be decomposed by autolysis. The inhibitor is contained, in the tissue of larvae, even in the acetone preparation, pupae, digestive juice and worm feces, but not in the blood and alimentary canal. When the worm is attacked with polyhedral virus disease or fed with nitrites, inhibiting ability of tissue is retained.
This inhibitor was isolated by extraction with diluted alkaline solution following pre-cipitation at about pH 4.2. On the basis of ultraviolet absorption spectrum and Murexide reaction, the inhibitor was deduced to be uric acid. Thence, the inhibiting action of uric acid was comparatively studied. Both the inhibitor isolated and pure uric acid diminished their inhibiting capacity by the pretreatment of mouse liver containing uricase, but not so in the case of fowl which has not such enzyme.
The reducing ability of larval tissue was attested by the removal of this inhibitor.
