Amino acid metabolism anaerobic

Hanson, R.B., and Gardner, W.S. (1978) Uptake and metabolism of two amino acids by anaerobic microorganisms in four diverse salt marsh soils. Mar. Biol. 46, 101-107. 

Amino Acid Metabolism Associated with Anaerobic Exercise... 

Note that breakdown products of fat metabolism (glycerol, propionyl-CoA), protein degradation (alanine, other amino acids), and anaerobic glycolysis (lactate) are substrates for gluconeogenesis. Notably, the primary breakdown product of fat, acetyl-CoA, is not shown, because it cannot be effectively used by animals in gluconeogenesis. Some of the substrates are summarized as follows ... 

With respect to amino acid metabolism some of the differences between host and parasite are somewhat subtle. Some parasite enzymes, for example, have properties which are clearly distinct from those of their mammalian counterparts, such as the cofactor dependence and regulation of glutamate dehydrogenases. The utilization of specific amino acids such as proline or the accumulation of others such as alanine reflects a difference in the relative importance of the pathways between parasite and host. Some differences are particularly striking, especially among anaerobic protozoa in... 

No studies of amino acid metabolism under anaerobic conditions appear to have been made with helophytes. Many helophytic species have been shown however to assimilate nitrate under conditions of partial anaerobiosis in the field (see Havill et al., 1974 Lee and Stewart, 1978) and it may be that such plants are able to maintain nitrate assimilation and intermediary nitrogen metabolism under partial anaerobiosis. 

Smith EA, Macfarlane GT. Dissimilatory amino acid metabolism in human colonic bacteria. Anaerobe. 1997 3 327—337. 

The next five transition metals iron, cobalt, nickel, copper and zinc are of undisputed importance in the living world, as we know it. The multiple roles that iron can play will be presented in more detail later in Chapter 13, but we can already point out that, with very few exceptions, iron is essential for almost all living organisms, most probably because of its role in forming the amino acid radicals required for the conversion of ribonucleotides to deoxyribonucleotides in the Fe-dependent ribonucleotide reductases. In those organisms, such as Lactobacilli6, which do not have access to iron, their ribonucleotide reductases use a cobalt-based cofactor, related to vitamin B12. Cobalt is also used in a number of other enzymes, some of which catalyse complex isomerization reactions. Like cobalt, nickel appears to be much more extensively utilized by anaerobic bacteria, in reactions involving chemicals such as CH4, CO and H2, the metabolism of which was important... 

That amines formed from naturally occurring amino acids are partly responsible for chronic hypertension is a rather attractive hypothesis first suggested by the experiments of Holtz (35). Besides the normal metabolic enzymes of amino acids, tissues, especially kidney, liver, and brain, contain amino acid decarboxylases, some of them specific for certain amino acids, some less so. These are anaerobic enzymes. After decarboxylation, certain monoamines are deaminated by amine oxidases which are sensitive to oxygen tension. The best known of these oxidases is the enzyme of Blaschko, Richter, and Schlossmann (9), which may be a mixture of three or more (29), and which is specific for many nonsubstituted vasoactive amines found in the body, with the notable exception of histamine. 

Physical or chemical modification of a substrate may additionally selectively affect transformation or uptake Keil and Kirchman (1992) compared the degradation of Rubisco uniformly labeled with 3H amino acids produced via in vitro translation to Rubisco that was reductively methylated with 3H-methane. Although both Rubisco preparations were hydrolyzed to lower molecular weights at approximately the same rate, little of the methylated protein was assimilated or respired. The presence of one substrate may also inhibit uptake of another, as has been demonstrated for anaerobic rumen bacteria. Transport and metabolism of the monosaccharides xylose and arabinose were strongly reduced in Ruminococcus albus in the presence of cellobiose (a disaccharide of glucose), likely because of repression of pentose utilization in the presence of the disaccharide. Glucose, in contrast, competitively inhibited xylose transport and showed noncompetitive inhibition of arabinose transport, likely because of inactivation of arabinose permease (Thurston et al., 1994). 

Availability is not the only constraint on substrate consumption. The value of a substrate is also related to the resources needed to convert the molecule into an intermediary metabolite. Thus in aerobic environments, monosaccharides and amino acids are readily consumed under anaerobic conditions, heterotrophic metabolism is largely fueled by small organic acids. Some taxa consume other types of substrates as long as they are reasonably abundant. Important examples include P-proteobacteria that consume phenols, a significant component of DOM inputs originating from plant material, and methylotrophs that consume single carbon compounds produced by anaerobic metabolism, photochemical reactions, and oxidation of methyl and methoxy substituents (Giovannoni and Rappe, 2000). 

The anaerobic mode of protein utilization is entirely possible in theory and in practice. Oxygen is not required for protein and nitrogen catabolism until the final stages of amino acid deamination have been reached. Complete anaerobic catabolism of proteins and nitrogen compounds (to the point where the final products C02, HjO and NH3 appear) has been known for a long time in prokaryotic organisms, but in eukaryotes only in parasitic worms, which are obligate anaerobes (von Brand, 1946). However, in recent decades, anaerobic metabolism of proteins has been found in some aquatic... 

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