Genesis Amino

The situation is, however, different in starvation. In this condition, it is the degradation of muscle protein that provides the amino acids for gluconeo-genesis, so that all the oxo-acids generated (except those for lysine and lencine) are nsed to synthesise the glucose required for oxidation by the brain. Hence, a process other than amino acid oxidation mnst generate the ATP required by gluconeogenesis. This process is fatty acid oxidation. 

Not surprisingly, the intake of sufficient carbohydrate to satisfy this demand is vital. If carbohydrate intake is low, glucose is provided in the short term (<24 hours in the adult) by breakdown of liver glycogen. After this period, glucose must be synthesised via the process of gluconeo-genesis primarily from amino acids released from the breakdown of muscle protein and from glycerol released... 

The kidneys main function is excretion of water and water-soluble substances (1). This is closely associated with their role in regulating the body s electrolyte and acid-base balance (homeostasis, 2 see pp.326 and 328). Both excretion and homeostasis are subject to hormonal control. The kidneys are also involved in synthesizing several hormones (3 see p. 315). Finally, the kidneys also play a role in the intermediary metabolism (4), particularly in amino acid degradation and gluconeo-genesis (see p. 154). 

Gortisol promotes net protein breakdown in skeletal muscle to provide amino acids as precursors for gluconeogenesis and ketone body synthesis (keto-genesis). 

When the reaction between aminoguanidine and sodium nitrite occurs in the presence of an excess of acetic acid, still another product is formed, namely, 1,3-ditetrazolyltriazine, the genesis of which is easily understood from a consideration of the reactions already mentioned. 5-Aminotetrazole is evidently formed first the amino group of one molecule of this substance is diazo-tized by the action of the nitrous acid, and the resulting dia-zonium salt in the acetic acid solution couples with a second molecule of the aminotetrazole. 

Figure 2.6. Formation of humic substances from quinones and amino acids, as illustrated by the reaction between catechol and glycine. Reprinted with permission from Stevenson, F. J. (1994). Humus Chemistry Genesis, Composition, Reactions, 2nd ed., John Wiley and Sons, New York.

The mode of biosynthesis of none of these alkaloids is known but, in the case of the iboga group, some guesses have been made (39, 63, 64), all of which start from the amino acids, tryptophan and dihydroxy-phenylalanine, and involve a fission of the latter s aromatic ring. A more sophisticated approach (65), starting from precursors of the aromatic amino acids, namely shikimic and prephenic acids, is apparently not in agreement with recent work on other indole alkaloids (66). The genesis of most indole alkaloids appears to stem from tryptophan and three... 

In some mammalian cells, enzymes comprising partial spans of biosynthetic pathways are inside and some outside the mitochondrial matrix space. Therefore, in the liver, six mitochondrial membrane transport proteins are required for urea synthesis, three for gluconeogenesis [7,8], and three others participate in ammonia-genesis [9] in the kidney. The synthesis of neurotransmitter substances such as acetylcholine, glutamate and y-amino butyric acid requires the participation of metabolite transporters in mitochondrial membranes of nervous tissue [9,10]. 

Proteinoids produced in laboratories can cluster together into droplets that separate, and that may protect their components from degrading influences of the surrounding environment. These droplets are like extremely simple cells, although they can not reproduce. Such droplets are called microspheres. When fats (i.e., lipids) are present, the microspheres that form are even more cell-like. If a mixture of linked amino acids called polypeptides, sugars called polysaccharides, and nucleic acids is shaken, droplets called coacervates will form. All of these kinds of droplets are called protobionts, and they may represent a stage in the genesis of cellular life. 

Radio astronomers have found that organic molecules (including amino acids), which might have played an important role in the formation of life, are present in dust clouds in outer space. Organic molecules are also known to be present in meteors that have fallen to Earth s surface. These observations provide further evidence that chemicals important for the genesis of life may have been present on the early Earth. The presence... 

Piredda, S. and Gale, K. (1986) Role of excitatory amino acid transmission in the genesis of seizures elicited from the deep prepiriform cortex. Brain Res., 377, 205-210. 

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