Pyridine nucleotides
The nucleotides nicotinamide adenine dinucleotide (NAD), nicotinamide adenine dinucleotide phosphate (NADP) and nicotinic acid adenine dinucleotide phosphate (NAADP) nicotinamide are sometimes referred to as pyridine nucleotides , because the basic structure of the nicotinamide ring they contain is based on the pyridine . In particular, NAD and NADP play a central role as hydrogen carriers and thus as reducing agents as coenzyme in numerous biochemical reductions . Together with the flavin adenine dinucleotide (FAD), they are the most important hydrogen carriers in the cell. In the oxidized form, the nicotinamide ring has a delocalized positive charge after the release of a hydride ion and the abbreviations of the oxidized forms are therefore NAD + and NADP + . The nicotinamide ring changes into the reduced form by absorbing a hydrogen ion and two electrons and the abbreviations for the reduced forms are therefore NADH and NADPH.
The biosynthesis of the pyridine nucleotides starts from nicotinic acid . The phosphate groups of a nicotinate mononucleotide and an adenosine mononucleotide are linked in the form of a phosphonic anhydride bond to form NAD. By phosphorylation at C2 'of Adenosinriboserests arises NADP, again NAADP is formed starting from the.
Individual evidence
- ^ Albert L. Lehninger, David L. Nelson, Michael M. Cox: Principles of Biochemistry . 2nd Edition. Spectrum Akademischer Verlag, Heidelberg, Berlin, Oxford 1994, ISBN 3-86025-106-6 .
- ^ Gertrud Rehner, Hannelore Daniel: Biochemistry of nutrition . 3. Edition. Springer, 2010, ISBN 978-3-8274-2041-1 , pp. 245-246 .