生物活性

• 描述NADP is nicotinamide adenine dinucleotide phosphate, acting as a key cofactor for electron transfer in the metabolism of all organisms, being alternately oxidized (NADP⁺) and reduced (NADPH). The nicotinamide adenine dinucleotide (NAD⁺))/reduced NAD⁺) (NADH) and NADP⁺)/reduced NADP⁺) (NADPH) redox couples are essential for maintaining cellular redox homeostasis and for modulating numerous biological events, including cellular metabolism. Deficiency or imbalance of these two redox couples has been associated with many pathological disorders. Cells maintain NADPH mostly in the reduced form to drive reductive biosynthesis and reactive oxygen species (ROS) detoxification, while the NADH pool is maintained mostly in the oxidized state to catalyze energy-producing reactions. In HeLa cells, mitochondrial pyridine nucleotide pools are connected asymmetrically, where oxidation of mitochondrial NADPH causes oxidation of mitochondrial NADH but not vice versa. The mechanism of this asymmetry is currently unknown but could be the result of the activity of transhydrogenase in the mitochondria. Such asymmetry may be beneficial to the cell since mitochondrial NAD+/NADH ratios fluctuate depending on ATP demand and respiratory fuel availability, while NADP+/NADPH reduction potential may need to remain stable to ensure adequate biosynthetic capacity and guard against oxidative stress.