Nicotinamide adenine dinucleotide cofactor

Electrocatalytic Oxidation of Nicotinamide Adenine Dinucleotide Cofactor at Chemically Modified Electrodes... 

Chemically modified electrodes (CMEs) for electrocatalytic oxidation of the reduced form of the nicotinamide adenine dinucleotide cofactor (NADH) are discussed. The work of the authors in the field is reviewed. CMEs based on adsorbed polyaromatic redox mediators (phenoxazines and phenothiazines) and the deposition of aqueous insoluble redox polymers are described. 

Nicotinamide adenine dinucleotide) Cofactors. See Coenzymes Coke, 339... 

NAD, NADH l Refer to the oxidised and reduced forms of the NADP, NADPH j nicotinamide-adenine dinucleotide cofactors of certain enzymes (see Figures 2a, b). 

Gorton L, Hale PD, Persson B, Boguslavsky LI, Karan HI, Lee HS, Skotheim TA, Lan HL, Okamoto Y. Electrocatalytic oxidation of nicotinamide adenine dinucleotide cofactor at chemically modified electrodes. ACS Symp Ser 1992 487 56-83. 

In oiological systems, the most frequent mechanism of oxidation is the remov of hydrogen, and conversely, the addition of hydrogen is the common method of reduc tion. Nicotinamide-adenine dinucleotide (NAD) and nicotinamide-adenine dinucleotide phosphate (NADP) are two coenzymes that assist in oxidation and reduction. These cofactors can shuttle between biochemical reac tions so that one drives another, or their oxidation can be coupled to the formation of ATP. However, stepwise release or consumption of energy requires driving forces and losses at each step such that overall efficiency suffers. 

The primary purification of the enzyme G3PDH was exploited herein as a preliminary study to investigate and demonstrate the feasibility of the integrated operation of cell disruption by bead milling and immediate product capture by fluidised bed adsorption (panel A in Figure 17.6). Yeast G3PDH binds nicotinamide adenine dinucleotide (NAD) as a cofactor,... 

All NOS isoforms utilize L-arginine as the substrate, and molecular oxygen and reduced nicotinamide adenine dinucleotide phosphate (NADPH) as cosubstrates. Flavin adenine dinucleotide (FMN), flavin mononucleotide (FAD), and (6R)-5,6,7,8-tetrahydro-L-biopterin (BH4) are cofactors of the enzyme. All NOS isoforms contain heme and bind calmodulin. In nNOS and eNOS,... 

Ethanol Electrodes The reliable sensing of ethanol is of great significance in various disciplines. The enzymatic reaction of ethanol with the cofactor nicotinamide-adenine dinucleotide (NAD+), in the presence of alcohol dehydrogenase (ADH)... 

Four of the B vitamins are essential in the citric acid cycle and therefore in energy-yielding metabolism (1) riboflavin, in the form of flavin adenine dinucleotide (FAD), a cofactor in the a-ketoglutarate dehydrogenase complex and in succinate dehydrogenase (2) niacin, in the form of nicotinamide adenine dinucleotide (NAD),... 

For the majority of redox enzymes, nicotinamide adenine dinucleotide [NAD(H)j and its respective phosphate [NADP(H)] are required. These cofactors are prohibitively expensive if used in stoichiometric amounts. Since it is only the oxidation state of the cofactor that changes during the reaction, it may be regenerated in situ by using a second redox reaction to allow it to re-enter the reaction cycle. Usually in the heterotrophic organism-catalyzed reduction, formate, glucose, and simple alcohols such as ethanol and 2-propanol are used to transform the... 

Zinc-containing alcohol dehydrogenases take up two electrons and a proton from alcohols in the form of a hydride. The hydride acceptor is usually NAD(P) (the oxidized form of nicotinamide adenine dinucleotide (NADH) or its phosphorylated derivative, NADPH). Several liver alcohol dehydrogenases have been structurally characterized, and Pig. 17.8 shows the environment around the catalytic Zn center and the bound NADH cofactor. 

Under conditions of copper deficiency, some methanotrophs can express a cytosolic, soluble form of MMO (sMMO) (20-23), the properties of which form the focus of the present review. The sMMO system comprises three separate protein components which have all been purified to homogeneity (24,25). The hydroxylase component, a 251 kD protein, contains two copies each of three subunits in an a 82y2 configuration. The a subunit of the hydroxylase houses the dinuclear iron center (26) responsible for dioxygen activation and for substrate hydroxylation (27). The 38.6 kD reductase contains flavin adenine dinucleotide (FAD) and Fe2S2 cofactors (28), which enable it to relay electrons from reduced nicotinamide adenine dinucleotide (NADH) to the diiron center in the... 

The most important product of the hexose monophosphate pathway is reduced nicotinamide-adenine dinucleotide phosphate (NADPH). Another important function of this pathway is to provide ribose for nucleic acid synthesis. In the red blood cell, NADPH is a major reducing agent and serves as a cofactor in the reduction of oxidized glutathione, thereby protecting the cell against oxidative attack. In the syndromes associated with dysfunction of the hexose monophosphate pathway and glutathione metabolism and synthesis, oxidative denaturation of hemoglobin is the major contributor to the hemolytic process. 

In the processes that require regeneration of cofactors such as nicotinamide adenine dinucleotide phosphate (NAD(P)H) and adenosine triphosphate (ATP), whole-cell biotransformations are more advantageous than enzymatic systems [12,15]. Whole cells also have a competitive edge over the isolated enzymes in complex conversions involving multiple enzymatic reactions [14]. 

The prodrug isoniazid (34) targets M. tuberculosis InhA [3] after activation by a mycobacterial catalase-peroxidase by reacting irreversibly with the cofactor nicotinamide adenine dinucleotide (NAD). This covalent adduct... 

Reliable measurements of L-lactate are of great interest in clinical chemistry, the dairy and vine industry, biotechnology, or sport medicine. In particular, blood lactate levels are indicative of various pathological states, including shock, respiratory insufficiencies, and heart and liver diseases. Silica sol-gel encapsulation of the lactate dehydrogenase and its cofactor was employed as a disposable sensor for L-lactate51. The sensor utilized the changes in absorbance or fluorescence from reduced cofactor nicotinamide adenine dinucleotide (NADH) upon exposure to L-lactate. 

Dehydrogenases, which represent a majority of redox enzymes, are mostly NAD (Nicotinamide Adenine Dinucleotide, see Fig. 12.9) dependent. This cofactor is not directly bound to the enzyme but its presence in the medium is necessary because it acts as a carrier of two electrons and one proton, and it activates the biocatalytic function of the enzyme. 

DHFR catalyses the hydride-ion transfer between the nicotinamide adenine dinucleotide phosphate (NADPH) cofactor and a substrate molecule (S) according to... 

A coenzyme is an organic compound that activates the primary enzyme to a catalytically active form. A coenzyme may act as a cofactor (see footnote 2), but the converse is not necessarily true. For example, the coenzyme nicotinamide adenine dinucleotide, in either its oxidized or reduced forms (NAD+ or NADH), often participates as a cofactor in enzyme reactions. 

Most asymmetric reductions that can be enzymatically effected have been the reactions of ketones. These reactions can be conducted with whole cells as well as with isolated enzymes. In the latter case, of course, at least one equivalent of a cofactor such as NADH or NADPH (nicotinamide adenine dinucleotide) is required to serve as the actual reductant in the reaction system. 

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