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The midpoint potential of the NAD + /NADH redox pair is −0.32 volts, which makes NADH a moderately strong reducing agent. [7] The reaction is easily reversible, when NADH reduces another molecule and is re-oxidized to NAD +. This means the coenzyme can continuously cycle between the NAD + and NADH forms without being consumed. [5]
NAD + is the oxidizing agent in glycolysis, as it is in most other energy yielding metabolic reactions (e.g. beta-oxidation of fatty acids, and during the citric acid cycle). The NADH thus produced is primarily used to ultimately transfer electrons to O 2 to produce water, or, when O 2 is not available, to produce compounds such as lactate or ...
Some anaerobic organisms use NADP +-linked hydrogenase, ripping a hydride from hydrogen gas to produce a proton and NADPH. [3] Like NADH, NADPH is fluorescent. NADPH in aqueous solution excited at the nicotinamide absorbance of ~335 nm (near UV) has a fluorescence emission which peaks at 445-460 nm (violet to blue).
Cellular respiration may be described as a set of metabolic reactions and processes that take place in the cells of organisms to convert chemical energy from nutrients into ATP, and then release waste products. [1] Cellular respiration is a vital process that occurs in the cells of all [[plants and some bacteria ]].
NADH dehydrogenase → plastoquinol → b 6 f → cyt c 6 → cyt aa 3 → O 2. where the mobile electron carriers are plastoquinol and cytochrome c 6, while the proton pumps are NADH dehydrogenase, cyt b 6 f and cytochrome aa 3 (member of the COX3 family). Cyanobacteria are the only bacteria that produce oxygen during photosynthesis.
When sufficient oxygen is not present in the muscle cells for further oxidation of pyruvate and NADH produced in glycolysis, NAD+ is regenerated from NADH by reduction of pyruvate to lactate. [4] Lactate is converted to pyruvate by the enzyme lactate dehydrogenase. [3] The standard free energy change of the reaction is -25.1 kJ/mol. [6]
In enzymology, a fumarate reductase (NADH) (EC 1.3.1.6) is an enzyme that catalyzes the chemical reaction succinate + NAD + ⇌ {\displaystyle \rightleftharpoons } fumarate + NADH + H + Thus, the two substrates of this enzyme are succinate and NAD + , whereas its three products are fumarate , NADH , and H + .
The cofactors NAD + and FAD are sometimes reduced during this process to form NADH and FADH 2, which drive the creation of ATP in other processes. [15] A molecule of NADH can produce 1.5–2.5 molecules of ATP, whereas a molecule of FADH 2 yields 1.5 molecules of ATP.