What is Metabolism ?
Metabolism is the chemical reactions that involved to maintain the cell and organisms. For human, metabolism process is the very important because it require the cellular metabolism which is involves the complex biochemical reactions that called metabolic pathways.
This metabolic pathways are important is breaking down the nutrients in order to produce energy. |
Protein Metabolism
Protein are the important tissue builders in body which it can help in the cell structure, functions, haemoglobin formation to carry oxygen, enzyme for metabolic reaction and other functions in the body. Also in supply the nitrogen for the DNA and RNA genetic materials and the energy production. This is because, protein contain long chain of amino acids.
Protein metabolism is the process to breakdown foods are used by the body to gain energy. During protein metabolism, some of the protein will converted into glucose through gluconeogenesis process. (Formation of glucose from non-carbohydrate sources). |
CATABOLISM :The process that is breaking down of things : A series of degradative chemical reactions that break down complex molecules into smaller units, and does not require energy because it is releasing energy.
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ANABOLISM :The process to building up of things : Chemical reaction that synthesizes molecules from the smaller components and usually require energy in process
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The general ways of amino acids degradation :
1. Deamination
- Elimination of amino group from amino acid with ammonia formation.
- Types of deamination :
i) Oxidative
ii) Reductive
iii)Hydrolytic
iv)Intramolecular
2. Transamination
3. Decarboxylation
1. Deamination
- Elimination of amino group from amino acid with ammonia formation.
- Types of deamination :
i) Oxidative
ii) Reductive
iii)Hydrolytic
iv)Intramolecular
2. Transamination
3. Decarboxylation
*Oxidative Deamination:
L-Glutamate dehydrogenase present in both cytosol and mitochondria to the liver.
L-Glutamate also take part in amino acids deamination.
L-Glutamate also take part in amino acids deamination.
*Transamination of Amino Acids*
The process of transferring of an amino group form an alpha-amino acid to an alpha-keto acid (alpha-ketoglutarate).
The enzyme that involved is aminotransferase (transaminase)
There are different reaction of transaminases between alanine aminotransferase and aspartate aminotransferase.
The enzyme that involved is aminotransferase (transaminase)
There are different reaction of transaminases between alanine aminotransferase and aspartate aminotransferase.
*Decarboxylation of Amino Acid*
The process to remove of carbon dioxide from the amino acid with formation of amines.
The enzyme that involved is decarboxylases. The coenzyme is pyrpdoxalphosphate |
Case for Protein Metabolism
CASE: DETOXIFICATION OF AMMONIA
A 60 year-old-woman suffers from cirrhosis of liver. Toxins such as ammonia are not properly metabolized by the liver and can damage brain. Which of the following compounds should be in highest concentration in brain as result of detoxification of ammonia?
- Alpha ketoglutarate
- Glutamine
- Glutamate
- Gamma amino butyric acid
- Asparagine
Cirrhosis of liver is a complication of liver disease which is involving the loss of liver cells and the irreversible scarring of the liver. In other meaning, this disease is the severe scarring of the liver and the poor liver function will show at the terminal stages of the chronic liver disease because it's often caused by the long-term exposure to the toxin such as alcohol or vital infection.
The highest concentration B (Glutamine) in brain will produce a result of detoxification of ammonia.
1. FIRST LINE OF DEFENSE:
The answer is referring to the mechanism of ammonia detoxification which occur at the first line of defense. Glutamate condense with the ammonia to produce Glutamine which is catalyzed by the glutamine synthetase. This process is requiring energy, so that the ATP acts as the source of energy for this reaction. The equation of the reaction shown below:
The highest concentration B (Glutamine) in brain will produce a result of detoxification of ammonia.
1. FIRST LINE OF DEFENSE:
The answer is referring to the mechanism of ammonia detoxification which occur at the first line of defense. Glutamate condense with the ammonia to produce Glutamine which is catalyzed by the glutamine synthetase. This process is requiring energy, so that the ATP acts as the source of energy for this reaction. The equation of the reaction shown below:
Diagram 1 The formation of glutamate to glutamine
Based on this result, the deamination of amino acids and amines are occurred. When it is exposed to the bloodstream as the glutamine, catalyzed by glutamate dehydrogenase to form glutamate from a-ketoglutarate and ammonium. After that, the glutamate will catalyzed by the glutamine synthetase to form glutamine and ammonium ion as the final product.
Then, the glutamine that produced will transported to the liver so that it can be converted to the urea in the liver by releasing the hydrolytic of the amide nitrogen form the glutamine as ammonia which is catalyzed by glutaminase in the liver. Next, the ammonia will released in the form of urea by detoxified.
2. SECOND LINE OF DEFENSE:
At this time, the excess ammonia will be released by involves the formation of Glutamate from the alpha-ketoglutarate which can used to synthesis the formation of glutamine. The same thing happen in the previous diagram. In this reaction, the Glutamate dehydrogenase is acts as the catalyzer because the NAD+ or NADP+ is used as the coenzyme and it’s a reversible reaction because the formation of alpha-ketoglutarate will directly release the ammonia for the urea synthesis. However, during the synthesis of glutamate to the glutamine catalyzed by glutamine synthetase, the reaction are irreversible.
3. THE EFFECTS OF AMMONIA INTOXICATION:
The ammonia intoxication happens when blood containing ammonium rises because of the capacity to detoxify it by the formation of glutamate and glutamine has been exceeded. There also can occur in infants where some of their blood ammonium has risen extreme high only can undergo the emergency treatment. In this case, the detoxification that happen in the old woman where the glutamine as the final product will transported out of her brain cells in exchange with tryptophan. Tryptophan is the precursor of Serotonin, whereas the Serotonin act as the neurotransmitter. If the quantity of Serotonin is excess so it will causes a state of hyper excitation.
In the process of ammonia detoxification, the glutamate and alpha-ketoglutarate are depleted. The decreasing of glutamate will form less GABA (Gamma AminoButyric Acid) as the product and therefore, resulting the state of hyper excitation. Besides, alpha-ketoglutarate also decreasing and resulting in a state of energy depletion because the intermediate of TCA cycle and depletion are the cause of the suppression of TCA cycle.
At the end, this old woman having symptoms of ammonia intoxication like blurring of vision, tremor, slurring when she speech, convulsions, coma and even can cause a death. The biochemical basis of this symptoms is depletion and hyper excitation due to the excess of serotonin production and the decreasing of GABA synthesis. Therefore, when a person have Cirrhosis of liver, the conversion of ammonia to urea is impaired and it she might or will has hyperammonemia other than the liver disorders blood and CSF Glutamine levels are increasing when she undergo a feature diagnostic of hepatic encephalopathy.