Coenzymes Species differences

Shinohara, A., Saito, K., Tamazoe, Y., Kamataki, T., and Kato, R., 1986, Acetyl coenzyme A dependent activation of N-hydroxy derivatives of carcinogenic arylamines Mechanism of activation, species difference, tissue distribution, and acetyl donor specificity. Cancer Res., 46 4362-4370. 

Many remarkable species differences have been found among the coenzymes. Most plants and animals synthesize their own ascorbic acid which is (among other tasks) essential for the hydroxylation of proline and lysine in the biosynthesis of collagen. However, Man, other primates, and the guinea pig are notable exceptions, so that for them, and for them alone, it is a vitamin, and must be taken in with food. 

It has been recognized for some years that there are species differences in some of the enzymes of fatty acid p-oxidation. Thus, physiochemical and chain length specificity differences have been found in the long chain acyl-coenzyme A dehydrogenase isolated from pig or beef tissue (Hall et al., 1976). Some differences in chain length specificity also appear to be present with the enzyme isolated from sheep or pig liver (Beinert, 1963). Whereas pig liver contained this enzyme with an acyl chain length preference of C4 to C16 and Ce to Cie, the enzyme from sheep liver was more reactive with the shorter acyl chain lengths. 

The nutritional need for accessory food factors was first stated explicitly in 1905-1906, although the influence of diet in preventing or curing some diseases such as scurvy had long been known. The name vitamine was proposed in 1912, but the terminal e was dropped when it was realized that not all these compounds are nitrogenous bases. The vitamins serve as coenzymes in various metabolic processes, and the necessary quantities are usually supplied by an adequate diet or by synthesis by the intestinal flora. Vitamin deficiency can arise from a failure to absorb the compound from the gut. The symptoms of deficiency vary in different animal species, and not all the substances found necessary in other species have been shown to be essential for human nutrition. Vitamins are used for the prevention or cure of deficiency diseases and for some other pathological conditions,... 

Fig. 1.2 Comparison of sequences of aspartate aminotransferases from different species. The residues are numbered according to the sequence of pig cAspAT.13 Possible deletions introduced into the sequences are indicated by hyphens. Residues that are invariant in pig c- and m-AspAT s are boxed, those that are invariant in pig AspAT s and coli AspAT are indicated as bold letters, and those that are directly interacting with substrate or coenzyme are marked as. ...

Aryloxyphenoxypropanoates and cyclohexanediones are two classes of herbicides that control many monocotyledoneous species. Although these herbicides are structurally very different (Fig. 1), there has been some conjecture that they have a similar mode of action because of their similarity in selectivity and symptomology. This paper describes the experiments that led to the discovery that aryloxyphenoxypropanoate and cyclohexanedione herbicides inhibit acetyl coenzyme A carboxylase (acetyl-coenzyme A bicarbonate ligase [ATP], EC 6.4.1.2) activity in susceptible species (1). In addition, evidence is presented indicating that the inhibition of acetyl coenzyme A carboxylase (ACCase) is well correlated to observed herbicidal activity. Similar, independent findings have recently been reported by two other research groups (2.3). 

Mitochondria contain ubiquinone (also known as coenzyme Q), which differs from plastoquinone A (Chapter 5, Section 5.5B) by two methoxy groups in place of the methyl groups on the ring, and 10 instead of 9 isoprene units in the side chain. A c-type cytochrome, referred to as Cyt Ci in animal mitochondria, intervenes just before Cyt c a h-type cytochrome occurring in plant mitochondria is involved with an electron transfer that bypasses cytochrome oxidase on the way to 02. The cytochrome oxidase complex contains two Cyt a plus two Cyt a3 molecules and copper on an equimolar basis with the hemes (see Fig. 5-16). Both the Fe of the heme of Cyt a3 and the Cu are involved with the reduction of O2 to H20. Cytochromes a, >, and c are in approximately equal amounts in mitochondria (the ratios vary somewhat with plant species) flavoproteins are about 4 times, ubiquinones 7 to 10 times, and pyridine nucleotides 10 to 30 times more abundant than are individual cytochromes. Likewise, in chloro-plasts the quinones and the pyridine nucleotides are much more abundant than are the cytochromes (see Table 5-3). 

Tke fermentative fixing of C02 and water to acetic acid by a species of acetobacterium kas been patented acetyl coenzyme A is tke primary reduction product (62). Different species of clostridia kave also been used. Pseudomonads (63) kave been patented for tke fermentation of certain (Q compounds and tkeir derivatives, eg, methyl formate. Tkese methods kave been reviewed (64). Tke manufacture of acetic acid from C02 and its dewatering and refining to glacial acid kas been discussed (65,66). 

There may be observed a noncompetitive type of inhibition in which it is assumed that the inhibitor S operates cither by being sorbed on a site adjacent to the substrate, where it slows down the rate-controlling step 3, or inhibiting the sorption of a coenzyme or other species on this adjacent site. The rate expressions in such a case have a form different from that just given for competitive inhibitions. ... 

Ribonucleotide reductases that do not contain tyrosyl radicals have been characterized in other organisms. Instead, these enzymes contain other stable radicals that are generated by other processes. For example, in one class of reductases, the coenzyme adenosylcobalamin is the radical source. Despite differences in the stable radical employed, the active sites of these enzymes are similar to that of the E. coli ribonucleotide reductase, and they appear to act by the same mechanism, based on the exceptional reactivity of cysteine radicals. Thus, these enzymes have a common ancestor but evolved a range of mechanisms for generating stable radical species that function well under different growth... 

The most important functions of pantothenic acid are its incorporation in coenzyme A and acyl carrier protein (AGP). Both CoA and AGP/4-phosphopantetheine function metabolically as carriers of acyl groups. Coenzyme A forms high-eneigy thioester bonds with carboxylic acids. The most important coenzyme is acetyl CoA. Acetic acid is produced during the metabolism of fatty acids, amino acids, or carbohydrates. The active acetate group of acetyl CoA can enter the Krebs cycle and is used in the synthesis of fatty acids or cholesterol. AGP is a component of the fatty acid synthase multienzyme complex. This complex catalyzes several reactions of fatty acid synthesis (condensation and reduction). The nature of the fatty acid synthase complex varies considerably among different species (91). 

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