Overview of amino acid metabolism.
Dietary proteins serve two functions: the carbon skeletons of their amino acids can be oxidized to yield energy, and their carbon and nitrogen atoms are used for the biosynthesis of several nitrogen-containing cellular constituents. Please explain:
- the overview of amino acid metabolism (just in a diagram) from dietary protein until urine (including creatinine, NH4+, uric acid, CO2 and H2O, Bilirubin, etc)
- Fate of protein of your diet from digestion until adsorbtion including the regulatory (hormones and enzymes) which involve.
- What do you know about zymogen?
- What is the function of hydrochloric acid in digestion?
Biosynthesis of nonessential amino acid: from krebs cycle intermediates.
Amino acids are grouped according to whether they are essential or nonessential components of the diet. What is the essential and nonessential amino acid?
A man can synthesize the nonessential amino acid, so, it is Important to you to know the biochemical of the reactions involved. Name and draw the structure of the α-keto acid resulting when each of the following amino acids undergoes transamination with α-ketoglutarate: (a) aspartate, (b) glutamate, (c) alanine, (d) phenylalanine.
Biosynthesis of nonessential amino acid: from monosaccharide and individual amino acid
Amino acids are grouped according to whether they are essential or nonessential components of the diet. What is the essential and nonessential amino acid?
A man can synthesize the nonessential amino acid, so, it is Important to you to know the biochemical of the reactions involved. Please explain the amino acid synthesis from monosaccharide! What kind of amino acid can be produced by monosaccharide?
What kind of amino acid can be produced by individual amino acid? And please write the reaction of it!
The Cost of Nitrogen Removal and Distribution of Amino Nitrogen.
The three carbons in lactate and alanine have identical oxidation states, and animals can use either carbon source as a metabolic fuel. Compare the net ATP yield (moles of ATP per mole of substrate) for the complete oxidation (to CO2 and H2O) of lactate versus alanine when the cost of nitrogen excretion as urea is included.
If your diet is rich in alanine but deficient in aspartate, will you show signs of aspartate deficiency? Explain.
A Genetic Defect in Amino Acid Metabolism: A Case History.
A two-year-old child was taken to the hospital. His mother said that he vomited frequently,
especially after feedings. The child’s weight and physical development were below normal. His hair, although dark, contained patches of white. A urine sample treated with ferric chloride (FeCl3) gave a green color characteristic of the presence of phenylpyruvate. Quantitative analysis of urine samples gave the results shown in the table.
- Suggest which enzyme might be deficient in this child and propose a treatment
- Why does phenylalanine appear in the urine in large amounts?
- What is the source of phenylpyruvate and phenyllactate? Why does this pathway (normally not functional) come into play when the concentration of phenylalanine rises?
- Why does the boy’s hair contain patches of white?
Transamination and the Urea Cycle
What do you know about transaminasi?Please explain the urea cycle! Please
Hyperammonemia is associated with inheredited abnormalities of urea cycle enzymes. What enzymes who involve to this diseases?
Aspartate aminotransferase has the highest activity of all the mammalian liver aminotransferases. Why?
Ammonia Toxicity Resulting from an Arginine- Deficient Diet
In a study conducted some years ago, cats were fasted overnight then given a single meal complete in all amino acids except arginine. Within 2 hours, blood ammonia levels increased from a normal level of 18 μg/L to 140 μg/L, and the cats showed the clinical symptoms of ammonia toxicity. A control group fed a complete amino acid diet or an amino acid diet in which arginine was replaced by ornithine showed no unusual clinical symptoms.
- What was the role of fasting in the experiment?
- What caused the ammonia levels to rise in the experimental group? Why did the absence of arginine lead to ammonia toxicity? Is arginine an essential amino acid in cats? Why or why not?
- Why can ornithine be substituted for arginine?
Oxidation of Glutamate
Write a series of balanced equations, and an overall equation for the net reaction, describing the oxidation of 2 mol of glutamate to 2 mol of α-ketoglutarate and 1 mol of urea.
Alanine and Glutamine in the Blood
Normal human blood plasma contains all the amino acids required for the synthesis of body proteins, but not in equal concentrations. Alanine and glutamine are present in much higher concentrations than any other amino acids. Suggest why?
Treatment of Gout
Gout is a disease of the joints caused by an elevated concentration of uric acid in the blood and tissues. The joints become inflamed, painful, and arthritic, owing to the abnormal deposition of sodium urate crystals. The kidneys are also affected, as excess uric acid is deposited in the kidney tubules. Gout occurs predominantly in males.
Gout is effectively treated by a combination of nutritional and drug therapies. Foods especially rich in nucleotides and nucleic acids, such as liver or glandular products, are withheld from the diet. Major alleviation of the symptoms is provided by the drug allopurinol
Allopurinol, an inhibitor of xanthine oxidase, is used to treat chronic gout
Explain the biochemical basis for this treatment. Patients treated with allopurinol sometimes develop xanthine stones in the kidneys, although the incidence of kidney damage is much lower than in untreated gout. Explain this observation in the light of the following solubilities in urine: uric acid, 0.15 g/L; xanthine, 0.05 g/L; and hypoxanthine,
1.4 g/L.
Transformation of Aspartate to Asparagine
Write the net equation for the synthesis of aspartate (a nonessential amino acid) from glucose, carbon dioxide, and ammonia
There are two routes for transforming aspartate to asparagine at the expense of ATP. Many bacteria have an asparagine synthetase that uses ammonium ion as the nitrogen donor. Mammals have an asparagine synthetase that uses glutamine as the nitrogen donor. Given that the latter requires an extra ATP (for the synthesis of glutamine), why do mammals use this route?
