[The nitrate reductase activity of human saliva].
Investigations of human saliva reductase activity report the enzyme inactivation in 5-min heating at 50 degrees C, its maximal activity in neutral medium, reduced specific activity in the saliva dilution. Routine centrifugation inactivated nitrate reductase in supernatant, its activity in the precipitate hardly reached 10%. Combination of supernatant with precipitate recovered the baseline activity completely. Nitrates reduction into nitrites requires donor electrons. The latter are suggested to be present in the supernatant. Dehydrogenases substrates (lactate, pyruvate, malate, etc.) may act as donor electrons for nitrate reductase reaction. The addition of lithium lactate instead of supernatant to the precipitate partially recovered nitrate reductase activity. Biological role of salivary nitrate reductase is considered.
Khramov
V A
VA
D002138:Calibration; D002498:Centrifugation; D003124:Colorimetry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D050901:Nitrate Reductase; D009565:Nitrate Reductases / Q000032:analysis*; D012463:Saliva / Q000201:enzymology*; D013696:Temperature; D013997:Time Factors
D009565:Nitrate Reductases; D050901:Nitrate Reductase
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