Nicotinamide nucleotides
These coenzymes are derived from the vitamin, niacin. They are of two types, nicotinamide adenine dinucleotide (NAD') and nicotinamide adenine dinucleotide phosphate (NADP'). Collectively, they are called as pyr~dine nucleotides. In NAD', the pyridine ring is attached to a ribose molecule through glycosidic bond and the phosphate provides a link between adenosine and nicotinamide riboside. In NADP', an aqditional phosphate group is present in carbon atom 2 of the ribose molecule of adenosine component.