Protein And Amino Acid Metabolism Flashcards
What do positive and negative nitrogen balances signify?
+NB signifies and anabolic state and/or growth. Common examples include childhood growth, pregnancy, and convalescence.
-NB signifies a catabolic state. It occurs as the result of malnutrition, amino acid imbalance, and terminal diseases such as cancer.
How can a patient’s nitrogen balance be determined and what is considered normal?
By checking their blood urea in nitrogen (BUN) levels. normal levels are between 3.0 and 8.2 mg/dL (0.15 to 0.48 moms/L).
How do nitrogen intake and loss compare in a normal healthy adult?
In a healthy adult, nitrogen intake should equal its loss.
Which specific organelles contain aminotransferases, and which specific tissues require them?
Aminotransferases are found in the mitochondria and cytoplasm of liver, kidney, intestine and skeletal muscle cells.
An increase in aminotransferases in the blood stream is indicative of what?
Tissue damage.
What are the two clinically important aminotransferases?
Alanine aminotransferase (ALT) aka serum glutamate-pyruvate transaminase (SGPT) and aspartame aminotransferase (AST) aka serum glutamate-oxaloacetate transaminase (SGOT).
A patient has elevated Serum ALT levels; name some possible causes.
Viral hepatitis, liver cell necrosis, and prolonged circulatory collapse.
What possible diseases could a high serum AST be indicative of?
Myocardial infarction, biliary cirrhosis, liver cancer, pancreatitis, mononucleosis, alcoholic cirrhosis and strenuous exercise.
Where do the intermediates come from during mitochondrial respiration and how are they regenerated?
The intermediates are supplied by the tricarboxylic acid cyle and are regenerated by the oxidation of acetyl CoAmto CO2.
Maple syrup urine disease is a rare autosomal disease caused by a deficiency in what?
Branched-chain a-keto acid dehydrogenase (BCKD) activity.
What causes the distinct burnt maple sugar odor in patients suffering from Maple syrup urine disease, and what are some other symptoms of this condition?
The presence of branched-chain amino acids and their a-keto derivatives.
They also accumulate in the blood causing toxic effects on brain function and retardation.
What is the common treatment for maple syrup urine disease?
The patient is prescribed a synthetic diet limiting branched-chain amino acids (Val, Leu, Ile). Thiamine supplementation may also be beneficial.
Which deficiencies and defects cause hyperhomocysteinemia and homocystinuria?
B6, B12, and folic acid deficiencies and/or an inherited defect in the enzyme cystathionine beta-synthase.
Hyperhomocysteinemia is an independently risk factor in which diseases?
Atherosclerotic heart disease and stroke, plus eye lens dislocation, osteoporosis and mental retardation.
What is the primary purpose of tetrahydrobiopterin and how is it synthesized?
Tetrahydrobiopterin is an essential cofactor in the hydroxylations of the aromatic amino acids Phe, Tyr, and Trp and also in the production of nitric oxide (NO) from Arg.
It is bio synthesized from GTP via a pathway involving three enzymes and is regenerated by the reduced form of NADPH-dependent reduction of dihydrobiopterin catalyze do by dihydropteridine.
