Hs

Ô 6 CH3-CH3 0- O- "yo-y adenine mercaptoethylamine p_alanine diphosphate

ribose 3-phosphate acetyf-CoA

Figure 2.6 Coenzyme A, showing its constituent parts, and the reaction between coenzyme A and an acid

2.2.2 Nicotinamide Adenine Dinucleotide

Nicotinamide adenine dinucleotide (NAD+ and NADP+) are the reagents for alcohol to aldehyde, ketone or carboxylic acid oxidation-reductions. The equivalent reagents in the laboratory would be KMn04 or Na2Cr207 for oxidations and NaBH4 or LiAlH4 for reductions. The complexity of the molecule should not hide its essential reactive part, the nicotinamide portion (Figure 2.8). The rest of the molecule is a polar handle to orient it correctly in the enzyme active site.

Figure 2.7 There is a large increase in the ease of dissociation of an a-proton in a thioester compared with a normal ester, which is important for biosynthetic condensation reactions

,CONHp

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