Acetylpyridine adenine dinucleotide

Kinetic experiments with NADH or reduced acetylpyridine adenine dinucleotide (APAD), which reacts much more slowly than NADH, showed that the sequence of appearance of signals resulting from reduction of the iron-sulfur centers was 2, 3 -f 4, 1 34, 36). All centers were reduced with NADH at 4° within 6 msec 46). Earlier studies of Beinert and his colleagues (47) had shown that the half-time of the appearance of... 

Fig. 15. pH dependence of NADPH oxidase, NADPH to 3-acetylpyridine adenine dinucleotide (AP-DPN) transhydrogenase, and NADH oxidase activities of submito-chondrial particles (ETP). Conditions oxidase activities were measured in the presence of 2 mM NADH or NADPH, 0.25 M sucrose, 100 mM sodium phosphate for pH values 6-0, and 100 mM sodium acetate for pH values 5.0 and 5.5. ETP concentration was 2.16 mg/ml for the NADPH oxidase, and 0.216 mg/ml for the NADH oxidase assays. The transhydrogenase reaction was measured by the Aminco-Chance spectrophotometer at 400 minus 450 nm. The extinction coefficient used for reduced 3-acetylpyridine adenine dinucleotide at 400 nm was 2300 liters mole" cm" . Media were the same as in the oxidase assays. Dotted lines indicate uncertainty about the pH 5 rates because of possible acidity damage to ETP. The ordinate refers to nanomoles of NADPH or NADH oxidized min" x mg" of ETP protein at 30°. From Hatefi and Hanstein (,S0). 

Fig. 17. Effect of trypsin on the NADH oxidase, NADPH oxidase and the NADPH-to-NAD transhydrogenase activities of submitochondnal particles. The particles suspended in 0.26 M sucrose and 100 mAf sodium phosphate, pH 7.0, were treated with 0.1 mg trypsin per mg particle protein and incubated at (a) 0° or (b) 30°. At the intervals shown samples were removed and assayed at pH 6.0 and 7.0 for the activities shown. Transhydrogenase activity was measured either directly by reduction of 3-acetylpyridine adenine dinucleotide at 376 nm in the presence of cyanide-treated particles or by the increase in the rate of NADPH oxidation by submitochondrial particles after the addition of NAD. (A) NADH —> O2, ( ) NADPH —> Oi, and (O) NADPH —> NAD. From Djavadi-Ohaniance and Hatefi...

According to Ohnishi 121), the half-reduction potentials of the various iron-sulfur centers of the respiratory chain at pH 7.2 are as shown in Fig. 18. The value for center 1 is essentially in agreement with the results of Orme-Johnson et al. 46, 54) who found that reduced acetylpyridine adenine dinucleotide (Bo = —248 mV) can only reduce this center by 50%, while its oxidized form can effectively oxidize iron-sulfur center... 

The hemoprotein fraction has no NADPH-dependent activities, but reduces sulfite in the presence of MVH. The flavoprotein fraction catalyzes electron transfer from NADPH to diaphorase-type acceptors and to acetylpyridine adenine dinucleotide phosphate. It does not reduce sulfite, nitrite, or hydroxylamine with either NADPH or MVH as electron donor. The molecular weight of the flavoprotein is estimated to be... 

Acetylpyridine adenine dinucleotide phosphate, sulfite reductase and,... 

The hemoprotein fraction has no NADPH-dependent activities, but reduces sulfite in the presence of MVH. The flavoprotein fraction catalyzes electron transfer from NADPH to diaphorase-type acceptors and to acetylpyridine adenine dinucleotide phosphate. It does not reduce sulfite, nitrite, or hydroxylamine with either NADPH or MVH as electron donor. The molecular weight of the flavoprotein is estimated to be 470,000 (two-thirds of the whole enzyme). A similar flavoprotein with a molecular weight of 460,000 has been isolated from a S. typhimurium mutant, which requires cysteine for growth. Other genetic data on the S. typhimurium enzyme (394), which appears to be essentially identical to the E. coli sulfite reductase, are in agreement with the above results. Thus mutants lacking the flavoprotein or the hemoprotein component of the enzyme and containing only the appropriate partial activities have been obtained and the respective partial enzymes isolated. The absorption spectra of sulfite reductase preparations from the wild type and from these mutants are shown in Fig. 46, and the proposed structure for the two components of the wild-type enzyme is shown in Fig. 47. Reconstitution of NADPH-sulfite reductase by recombination of the flavoprotein... 

D-Glucitol dehydrogenase has broad substrate-specificity. The enzyme oxidizes D-glucitol, L-iditol, ribitol, and xylitol in the presence of NAD+ cofactor.414 424 NAD+ can be replaced by 3-acetylpyridine adenine dinucleotide (AcPyAD), 3-thionicotinamide adenine dinucleotide (TNAD), or nicotinamide hypoxanthine dinucleotide (NHD).414... 

Oxidized 3-acetylpyridine adenine dinucleotide phosphate. Oxidized 3-acetylpyridine adenine dinucleotide. 

Acetylpyridine adenine dinucleotide 3-Acetyl NAD C22H28N6O14P2 86-08-8 662.436 solid ... 

Acetylpyridine adenine dinucleotide, A-23 3-Acetylpyridine NAD, A-23 i -Acetyl-D-quinovosamine, A-380 i -Acetyl-L-quinovosamine, A-380... 

Acetylpyridine adenine dinucleotide, A-23 Adenosine cyclic 2, 3 -(hydrogen phosphate), A-32 Adenosine diphosphate ucose. A-36 Adenosine diphosphate ribose, A-37 Adenosine diphosphate, A-33... 

In enzymic assays, 3-acetylpyridine adenine dinucleotide (3-APAD) can replace NAD as substrate. No one has as yet succeeded in the direct bromination to form 3-bromo-APAD, although 3-chloro-APAD has been synthesized. If the ribose of the functional moiety of 3-APAD is replaced by a hydrocarbon chain, the redox potential is altered to —320 mV, a magnitude close to that of NAD+ Compounds of this structure can be easily labeled by using methyl or carbonyl-labeled acetylpyridine for synthesis. 

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