ITS BIOCHEMICAL FUNCTIONS

As noted on What is it and Where it Comes from, the active form of niacin (NAD/NADP) plays an important role in

1. Transportation of certain nutrients.

2. Metabolism of carbohydrates, fats, and porteins

3. cell respiration

4. proper functioning of the nervous and circulatory system.

5. synthesis of hormones, fatty acids, and steroids.

6. regulatation of cholesterol and building of red blood cells.

The coenzyme forms of niacin are involved in over 40 biochemical reactions.

They specificly play very important roles in

• glycoysis (the conversion of glucose is converted to glycogen in the liver and muscles)
• pyruvate metabolism (the oxidation of carbohydrate compounds to get ATP energy)
• formation of high energy phosphate bonds
• pentose synthesis (the making of simple 5 carbon sugars)

NADH/NAD+ vs. NADPH/NADP+

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NAD and NADP are very different in terms of the reactions they take part in.

NADH/NAD+ ---

is a major coenzyme in biochemical reactions involving energy transfer. It plays an important role in glycolysis (involving the enzyme G-3_P dehydrogenase), the TCA cycle (citric acid cycle--an integral part of cellular respiration) involving a-ketoglutarate dehydrogenase, beta-oxidation, and the electron transport chain.

NADPH/NADP+ ---

is a major coenzyme in fatty acid synthesis and cholesterol synthesis.

Both are usually involved in in dehydrogenase and reductase reactions that involve hydrogen transfer.

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The following pages explore indepth some of the biochemical reactions that involve NAD or NADP.

CELLULAR RESPIRATION

GLYCOLYSIS

ELECTRON TRANSFER

KREBS CYCLE

REDUCTASES/DEHYDROGENASES

ALDEHYDE REDUCTASE (from pig kidneys)

GLUTHATHIONE REDUCTASE

3- A - HYDROXYSTEROID DEHYDROGENASE FROM PSEUDOMONAS TESTERONI

THIOREDOXIN REDUCTASE

FATTY ACID SYNTHESIS

PENTOSE PHOSPHATE PATHWAY