Ribose biologically important derivatives

Adenosine A nucleoside that is composed of adenine and d-ribose. Adenosine or adenosine derivatives play many important biological roles in addition to being components of DNA and RNA. Adenosine itself is a neurotransmitter. [NIH]... 

Two derivatives of nicotinamide (pyridine-3-carboxylic amide), one of the B2 vitamins, nicotinamide adenine dinucleotide (NAD ) and nicotinamide adenine dinucleotide phosphate (NADP ), serve as redox coenzymes. Of the three heterocyclic ring systems found in these coenzymes, i.e. those of purine, ribose and pyridine, it is the pyridine portion that is reactive in redox reactions. Biologically, two oxidation states are important the oxidized form, NAD(P)+, and the 1,4-dihydro isomer of the two-electron reduced form, NAD(P)H (Scheme 1). Nicotinamide coenzymes interconvert between these two oxidation states in... 

The chemistry of phosphate esters is rich and varied. Phosphate esters are important in biological systems. The phosphate ester of a nucleoside (a nucle-obase attached to a ribose derivative see Chapter 28, Section 28.5) is called a nucleotide. These are structural components used in DNA and RNA. Using adenosine (210) as an example, there are three possible monophosphate esters 211, 212, and 212. The pyrophosphate (diphosphate) derivative is adenosine 5 -diphosphate (214). The symbol A is used to designate an adenosine derivative in biology, so 211 is abbreviated 5 -AMP (adenosine 5 -monophosphate) and 214 is 5 -ADP (adenosine 5 -diphosphate). The numbering is explained in Chapter 28, Section 28.5. 

A complex pyridinium derivative, nicotinamide adenine dinucleotide (NAD ) is an important biological oxidizing agent. The structure consists of a pyridine ring [derived from 3-pyridinecarboxylic (nicotinic) acid], two ribose molecules (Section 24-1) linked by a pyrophosphate bridge, and the heterocycle adenine (Section 26-9). 

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