Amino Acid Flashcards
(30 cards)
Avg turnover of protein in adults
300-400g per day
What are the rough half-lives of different types of proteins
Most - days
Structural eg collagen - years
Hormones and digestive enzymes - degraded in minutes
What is the recommended protein intake
50-70g
What is positive nitrogen balance and when does it occur
Nitrogen synthesis > excretion
Child growth
After serious illness
After immobilisation due to an accident
Pregnancy
How are foreign, exogenous proteins broken down
1Taken into vesicles by Endocytosis or Autophagocytosis
2. fuse with vesicles containing PROTEOLYTIC ENZYMES which degrade proteins to amino acids
What increases rate of protein breakdown
Starvation and Hormones eg cortisol increases protein breakdown in muscle
What are amino acids degraded to initially
NH2 and oxo acid (keto acid)
Oxidative deamination equation
Amino acid + water + coenzyme —> keto acid + ammonia + coenzyme-2H
Trans animation equation
Amino acid 1 + keto acid 2 —> amino acid 2 + keto acid 1
** Explain the concept of nitrogen balance
the rate of body protein synthesis (and other N- containing compounds) is equal to the rate of degradation.
- Explain how amino acids are classified as essential or nonessential and the significance of this classification;
essential amino acids = not made by the body so must be in diet
-non essential; humans synthesis 10 from intermediates
- Explain the terms transamination and deamination
- trans: N part of the amino acid is removed by transfer to an acceptor molecule
- deamination: RELEASE OF NH2 GROUP AS AMMONIA NH3 or NH4+
what are the causes of negative nitrogen balane
- in starvation,
- during serious illness,
- In late stages of some cancers,
- in injury and trauma.
- If not corrected and becomes prolonged, there will be irreversible loss of essential body tissue
- lead to death.
- Explain the importance of glutamine
- safe carrier of ammonia
- carry 2 amminia equivilants to liver - urea
- deiver amminium ions to kidney for buffering
- Explain transdeamination
transamination followed by oxidative deamination.
yields pyrvuate, and glutamate.
what system removed old or damaged proteins
ubiquitin breakdown system
gives mixture of amino acids
what are ketogenic amino acids
only degraded into acetyl CoA
leucine and lysine
what are glycogenic amino acids
in starvation, amino acids w carbon skeletons of 13 of the amino acids are converted back to glucose
what are both glycogenic and ketogenic
phenylalanine and tyrosine - part of their structure converted to glucose
(also typtophan, threonine and isoleucine)
role of liver in N metabolism
- remove aa, glc and fat from portal blood supply
- absorb aa for protein synthesis
- synth plasma proteins
- synth ahem, purines and pyrimadines - RNA and DNA
- degrade excess aa - Transdeamination
- NH3 –> urea for excretion. ornithine cycle
examples of plasma proteins
albumin
clotting factor
lipid transport proteins
examples of plasma proteins
albumin
clotting factor
lipid transport proteins
what are amine groups NH2 transported as in the blood
glutamine
what organ converts amino groups to urea
liver
