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de amino acid refers to the process by which
amino acids
are de-amino-produced and de-α by enzyme catalysis. This is the main way amino acids break down in the body. There are 20 amino acids involved in the synthesis of human
protein
, their structure is different, the way of deamining is also different, mainly oxidizing deamining, transamination, combined deamining and non-oxidizing deamining, etc., in order to joint deamine is the most important.(i) Oxidation deaminationOxidation deamination refers to the process by which amino acids take off amino acids while oxidizing dehydrogenation under the catalysis of enzymes.oxygen-free
dhydrogenase
catalytic oxidation deaminizing actionglutamate mitochondrials are catalyzed by glutamate dehydrogenase (glutamate dehydrogonase). Glutamate dehydrogenase system does not require oxygen dehydrogenase, with NAD plus or NADP plus as coenzyme. The oxidation reaction is transferred by glutamate C alpha dehydrogenation to NAD(P) plus to form α subamine diacid, and then hydrolytically produces α ketone diacin and ammonia.glutamate dehydrogenase as a variant enzyme. GDP and ADP are variant activators, and ATP and GTP are variant inhibitors.in the body, glutamate dehydrogenase catalyzes reversible reactions. In general, the synthesis of glutamate (G'≈30kJ-mal1) is preferred because high concentrations of ammonia are harmful to the body, and this reaction balance point helps to maintain a low ammonia concentration. However, when glutamate concentration is high and NH3 concentration is low, it is beneficial to the α deamine and ketone diacin.(ii) TransaminationTransamination refers to the process of transferring the amino acid α-amino acid to another α- ketone acid under
transaminase
catalysis, producing the corresponding α ketone acid and a new α-amino acid.of amino acids in the body are deamined by transamination. Of the 20 α-amino acids involved in protein synthesis, except glycine, lysine, suline and proline do not participate in transamination, the rest can be catalyzed by specific transaminase to participate in transamination. The most important amino subjects for transaminogen are α ketone diacin, which produces glutamate as a newly generated amino acid:further transfers aminos from glutamate to oxalic acid, producing α ketone diacin and tylenol:or to acetone. The α ketone diacin and alanine are produced and regenerated by a second transamination reaction α ketone diacin.has strong glutamic transaminase (gPT) and glutamic oxaloacetic trans aminase (GOT) activity in the body.the trans-amino action is reversible, and the reaction is ≈0, so the equilibrium constant is about 1. The direction of the reaction is taken from the relative concentration of the four reactants. Therefore, trans-amino action is also an important way to synthesize certain amino acids (non-essential amino acids) in the body.. 2. Trans-amino action structure: -trans-amino action process can be divided into two stages: (1) the amino acid amino to the enzyme molecule, producing the corresponding ketoic acid and aminoase: (2) NH2 transferred to another ketoic acid, (e.g.α one-ketone diacid) produces amino acids and releases enzyme molecules:for the transmission of the NH2
gene
, transaminase requires the participation of its aldehyde-based coenzyme- pyridoxal-5'-phosphate, PLP). During the transamino- process, coenzyme PLP is converted to pyridoxamine5'phosphate, PMP). PLP forms Schiff alkali by shrinking the lysine omega amino in its aldehyde base and enzyme molecules and co-prices binding subenzyme molecules. . Esmond Snell, Alexan de Branstein and David Metgler, between them, reveal that transamination is a ping-pong mechanism, with two phases in three steps each. Phase I: The pro-nucleic NH2 group of amino acids converted to ketone acid (1) amino acids acts on the enzyme PLp Schiff alkali C atom, forming an amino acid PLp Schiff base by transimination or transSchiffigation, while restoring the NH2 group of lysine in the enzyme molecule. (2) The amino acid Lp Schiff alkali molecule is rear-rowed into a α ketone PMP schiff base by catalysis of the enzyme-active bit lysine to remove the amino acid α hydrogen and add protons to the 4th C atom of the PLP through a resonant and stable intermediate product. (3) hydrolytically produces PMP and α-ketoic acid. Phase II: α-ketone acid to amino acid In order to complete the transamination reaction cycle, coenzyme must change from PMP to E-PLp-Schiff, a process that also consists of three steps for the reverse process of the above reaction. (1) PMP is formed α ketoacide-Schiff base α a ketone-ketoacide. (2) molecular reartease, α-ketonic acid-PMp-Schiff alkali becomes amino acid-PLP-Schiff base. (3) Enzyme active point lysine omega-NH2 group attacks the amino acid -PLp-Schiff alkali, produces an active enzyme-PLP Schiff base by trans-amino, and releases the formation of new amino acids. trans-amino reaction, coenzyme converts between PLP and PMP, acting as an amino carrier in the reaction, and amino transfer between α-ketone acid and α-amino acid. It can be seen that there is no net NH3 generation in trans-amino reactions. . 3. The physiological significance of trans-amino plays a very important role in trans-amino. The type and quantity of non-essential amino acids in the body can be regulated by transamination to meet the demand for non-essential amino acids when proteins are synthesized in the body. -transamino is also an important part of the combined deamino action, thus accelerating the transformation and transport of ammonia in the body, and linking the body's sugar metabolism, lipid metabolism and amino acid metabolism. (iii) the combined deamination the combined deamination is the main way of de-ammonia in the body. There are two main reaction pathways: 1. The combined deamination by L-glutamate dehydrogenase and transaminase: first, the α-amino of an amino acid is transferred to the α Glutamate is produced on ketone diacid, and glutamate oxidation and deamination are then produced under L-glutamate dehydrogenase α, while α-ketone diacid continues to participate in transamination. . L-glutamate dehydrogenase is mainly distributed in the liver, kidney, brain and other
tissues
, and α-ketone diacids to participate in the transamination role is common in various organizations, so this kind of combined deamination is mainly carried out in liver, kidney, brain and other tissues. The combined desamine reaction is reversible and therefore can also be called combined ammonia. . 2.
nucleotide
cycle: L glutamate dehydrogenase activity in skeletal and cardiomyopathy tissue is very low and therefore cannot be desamined by the combined desalination reaction in the above form. However, skeletal and cardiomyopathy are rich in adenoside deaminase, which catalytic adenosine watering and desamine produces secondary jaundice nucleotides (IMP). an amino acid that transfers α-amino to acetic acid to produce mendonine after two transaminations. Mendonine can also transfer this amino to the secondary jaundice nucleotide to produce adenine nucleotides (through intermediate
compounds
adenosine seine). currently believes that the circulation of nirconium nucleotides is the main way to de-ammonia the amino acids in skeletal and cardiomyopathy. John Lowenstein has demonstrated that this nucleotide cycle plays an important role in muscle tissue metabolism. Increased muscle activity requires the increased cycloic acid cycle for energy. This process requires an increase in the intermediate products of the triacetic acid cycle, and the lack of enzymes in the muscle tissue that catalyz this compensatory reaction. Muscle tissue relies on this niobium nucleotide cycle to supplement the intermediate product, grass acetic acid. Studies have shown that all three enzymes in muscle tissue that catalyz the cycling reaction of nirconium nucleotides are several times more active than in other tissues. AMP deaminase genetic defects patients (myodenine deaminase deficiency) are prone to fatigue, and often after transport painful spasms. this form of combined deamining is irreversible and therefore cannot be synthesized with non-essential amino acids through its inverse process. This metabolic pathway not only connects amino acid metabolism with sugar metabolism and lipid metabolism, but also connects amino acid metabolism with nucleotide metabolism. (iv) non-oxidizing deamination certain amino acids can also remove aminos through non-oxidizing deamination. . 1. Dehydrated deaminate, such as serine, can produce ammonia and acetone acid under the catalysis of serine dehydrase. , under the role of suline dehydrase, produces α-ketone butyric acid, which is then metabolized by acrylamide A, amber aoC, as shown in the figure below. this is one of the ways suline breaks down in the body. . 2. Hydrogen desulfurized cysteine can produce acetone and ammonia under the catalysis of desulfurized hydrogenase. . 3. Direct deaminate can directly de-ammonia under the action of tiandongease to produce Yanhuso acid and ammonia.
.
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