Cofactors and Coenzymes

Mainly in archaebacteria the other coenzymes and cofactors occur in many organisms but not all synthesise them. 

Chapter 3 The Physiologic Roles of Enzymes 33 Table 3-3. Physiologic functions of coenzymes and cofactors. 

Dolphin, D., Poulson, R., and Avramovic, O., eds. (1989) Glutathione-Chemical, Biochemical and Medical Aspects (Coenzymes and Cofactors), Vol. 3, Wiley, New York (Parts A B)... 

Part 3, Catalysis, is divided into four chapters. The first three chapters in part 3 deal with the properties and functions of enzymes. The last chapter explains the essential properties of coenzymes and cofactors. 

Figure 5.2 Chemical structures of three common coenzymes NADH, ATP, and coenzyme A. Since coenzymes and cofactors are often complex and expensive molecules, their regeneration is crucial in industrial biocatalysis applications.

Understand the role of coenzymes and cofactors in enzymatic catalysis. 

The RNA-related nature of most coenzymes and cofactors, the role of RNA in the translation process, and the catalytic abilities of RNA show that RNAs have played a crucial role in early biochemistry and have supported the hypothesis of an RNA world (11). In this scenario, living organisms primarily used RNA for both catalysis and information storage before the advent of coded peptides and of the translation apparatus. But most supporters of this scenario believe that amino acids and... 

Other Coenzymes and Cofactors.— The chemical synthesis of riboflavin phosphates and their acetyl derivatives has been reinvestigated. Riboflavin 4 -monophosphate (10) is an important contaminant of commercial flavin mononucleotide (FMN), and... 

Enzyme Coenzymes and Cofactors Allosteric Modulators Positive Negative Equilibrium Constant atpH7.0(K ) AG° kcal/mol (kj/mole)... 

A comprehensive nutrition assessment must include an evaluation of possible trace element, vitamin, and essential fatty acid deficiencies. Because of their key role in metabolic processes (as coenzymes and cofactors), a deficiency of any of these nutrients may result in altered metabolism and cell dysfunction, and may interfere with metabolic processes necessary for nutritional repletion. The evaluation of single-nutrient-deficiency states includes an accurate history to identify symptoms and risk factors that may indicate deficiency or predispose the patient to developing a deficiency state. A focused physical examination for signs of deficiencies and biochemical assessment to confirm a suspected diagnosis also should be done. Ideally, biochemical assessment would be based on the nutrient s function (e.g., metalloenzyme activity) rather than simply measuring the nutrient s serum concentration. Unfortunately, few practical methods to assess micronutrient function are available currently, and most assays measure serum concentrations of the individual nutrient. 

The terms coenzyme and cofactor are used as synonyms here, as seems to be the case in most textbooks (see Ref. [1] as an example). Duine (2004) has suggested specific distinctions among these and related terms but the distinctions appeared not to be crucial for the discussions in this chapter, which deals with non-enzymic reactions. 

Wbsthbimer, F. H. 1987 in Coenzymes and Cofactors, Vol. II Part A, Pyridine Nudeotide Coenzymes, ed. 

E. W. Miles, Pyridoxal phosphate enzymes catalyzing fl-elimination and 3-replacement reactions, in Pyridoxal Phosphate and Derivatives, Vol. I in the series Coenzymes and Cofactors, (eds. D. Dolphin, R. Poulson, and O. Avramovic), John Wiley and Sons, New York, 1986, pp. 253-310. 

The chemical potential of side chains found in amino acids is limited for example, there are no efficient electron acceptors. Therefore, enzyme catalysis incorporates if necessary additional chemical potential by specific metal ions, for example, Zn2+ (see Fig. 1-6), Fe2+ Co2+, Cu2+ and others Examples are shown in Fig. 1-8 for the coordination of the transition metal ions in protein structures. Besides metal ions, cofactors or coenzymes serve to activate groups and participate in the catalytic process. A summary of cofactors and coenzymes is given in Table 1-4 the relation to vitamins is quite apparent. Chemical structures are presented in Table 1-5. Coenzymes and cofactors may act by nucleophilic or electrophilic attack on the sub-... 

The important area of oxidation-reduction enzymes, covered in Volumes XI-XIII, will complete the third edition of The Enzymes. Some of the most remarkable examples of biological catalysis and versatility of coenzyme and cofactor function are found within this group. As with previous volumes, the excellent quality is a result of the outstanding and well-recognized contributors. For planning the volumes on oxidation-reduction, the Editor and readers are indebted to the Advisory Board Members, namely. Professors Britton Chance, Lars Ernster, Bo Malmstrom, and Vincent Massey. 

D. Dolphin, R. Poulson, O. Avramovic, Coenzymes and Cofactors, Wiley Sons, New York, 1987. 

M Ebadi. Catabolic pathways of pyridoxal phosphate and derivatives. In D Dolphin, R Poulson, O Avramovic, eds. Coenzymes and Cofactors, Vol. 1. Vitamin Be—Pyridoxal Phosphate Chemical, Biochemical and Medical Aspects, part B. New York John Wiley Sons, 1986, pp 449-476. 

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