Biochem: FINAL (Ch. 28-29) Protein & Amino Acid Catabolism

Converted from slide show Includes Urea cycle

What are some conditions/ states that lead to positive nitrogen balance? (3)

infants, pregnancy, growth periods

What are some conditions/ states that lead to negative nitrogen balance? (3)

surgery, illness, low protien/ carbohydrate diets

What does ubiquitin do?

attachs intracellular proteins marked for degradation

What do lysosomal proteases do?

breakdown proteins into smaller peptides

What do lysosomal peptidases do?

Break down peptides to form individual amino acids?

About how much of the body’s total protein content is turned over daily?

1-2%

What are the (2) components that amino acids are catabolized into?

the amine group and the amphibolic intermediate

What can the amphibolic intermediate product of amino acids be used for? (4)

The synthesis of glucose, ketone bodies, fatty acids, or energy

What is NH₃?

Ammonia

What are the (4) stages of urea synthesis?

transamination of other amino acids to glutamate, oxidative deamination of glutamate to form ammonia, transporting ammonia from the blood to the liver, and the urea cycle

What is the only substrate used in oxidative deamination? Why?

glutamate because all other amino acids can eventually be transaminate into glutamate

What does Glutamate dehydrogenase do?

converts glutamate and NAD into alpha-ketoglutarate, NADH, and ammonia (NH3)

Where is ammonia (NH₃) transformed into ammonium (NH_4⁺)?

the liver

Where is glutamate dehydrogenase found? (2)

mostly skeletal muscle and colonic bacteria

What can serve as an oxidoreducant in the creation of glutamate?

NAD+ or NADP+

What usually causes Ammonia Toxicity?

portal blood/ systemic blood bypassing the liver due to cirrhosis or liver failure

What is one body mechanism that can be used to help relieve Ammonia toxicity?

glutamine synthesis

What does carbamoyl phosphate synthase I do?

It converts CO2 and ammonium into carbamoyl phosphate using ATP

Where does Urea synthesis take place in the cell?

the cytosol

Where does carbamoyl phosphate synthase I act within the cell?

The mitochondria

What is the point of making carbamoyl phosphate in urea synthesis?

To transport ammonium out of the mitochondria into the cytosol in the form of citrulline

What amino acid is involved in the urea cycle?

aspartate

What is one of the products made in the urea cycle that eventually enters the citric acid cycle?

fumarate

What is the direct precursor to urea?

Argentine

What molecule is recycled in the urea cycle to continue the process?

ornithine

How many different amiphibolic intermediates are formed during amino acid catabolism?

7

What processes can amiphibolic intermediates go onto complete?

gluconeogensis and ketogensis

What are the ketogenic amino acids?

leucine and lysine

What does it mean to be a Glycogenic amino acid?

your amphibolic intermediates can form pyruvate or citric acid cycle intermediates and be converted into glucose

When are Glycogenic/ Ketogenic amino acids used?

during fasting or uncontrolled Type 1 diabetes

What does it mean for an amino acid to be ketogenic?

your amphibolic intermediates can form acetyl CoA or acetoacetyl CoA

What are the (4) glycogenic and ketogenic amino acids?

isoleucine, phenylalanine, tryptophan, tyrosine

What amino acids’s amphibolic intermediates can be used to create acetoacytl-CoA? (5)

leucine, lysine, pehnylalanine, tryptophan, tyrosine

What amino acids’s amphibolic intermediates can be used to create pyruvate?(6)

Alanine, cysteine, glycine, proline, serine, threonine

What amino acids can form acetyl-CoA?

Isoleucine, leucine, and tryptophan

What is cystinuria?

A defect in renal reabsorption of cystine that causes cystine crystals in urine

What is Alkaptonuria?

high urine homogentisate levels that is a defect in tyrosine metabolism that causes urine and connective tissue to turn dark and arthritis

What is Maple Syrup urine disease?

A defect in branched-chain amino acid metabolism (leucine, valine, and isoleucine) which causes ketoacidosis, neurological and intellectual disabilities.