Essential Amino Acids

Nonessential
1. Synthesis
  1. C-skeleton
    1. from glucose catabolism
      1. serine
      2. glycine
  2. N groups
    1. from other aa
      1. essential aa
        Phe --> Tyr
        Met (S), Ser (C) --> Cys
        dietary intake
        reduce requirement
        Met, or Phe
Role of Glutamate
1. transfers N
  1. transamination
    1. a-ketoacids
      1. pyruvate --> alanine
      2. OAA --> aspartate
  2. obtained
    1. other aa
    2. NH4+
2. glutamate dehydrogenase
  1. reversible
  2. a-ketoglutarate --> glutarate
  3. no ATP
3. AA related
  1. arginine
    1. onthinine
      1. use urea cycle enzymes
        intestinal mucosa
        ornithine --> citruline
        lack arginase
        no urea synthesis
        kidney
        citruline --> arginine
    2. essential in infancy
      1. total protein requirement
        higher
        infants and children
        % of essential aa
        protein quality
        capacity of diet to provide essential aa
        aa score
        content of individual EAA in food protein/content of EAA in reference protein
        (mg/g)
        most likely to affect
        lys
        met (+cys)
        thr
        trp
        complete
        animal
        incomplete
        vegetable
  2. proline
    1. glutamate semialdehyde
      1. spotaneous cyclization
        reductase
        proline
        uses NADPH
        reverse rxn
        FAD
  3. glutamine
    1. glutamine synthetase
      1. NH4+ and ATP
        amide bond formed
      2. irreversible
      3. reverse rxn
        glutaminase
      4. in muscle
        normal
        low levels
        muscle wasting
        increased levels
        reduce?
        refeeding
        endurance exercising
        restore insulin levels
        anabolic steroids
    2. role
      1. protein synthesis
      2. N donor
        purines
        pyrimidines
        NAD+
        amino sugars
        asparagine
      3. glutamate donor
        glutathione
        GABA
        Ornithine
        arginine
        proline
Protein Complementation
1. combine proteins
  1. complementary aa deficiencies
    1. higher biological value
      1. rice & beans
      2. corn totillas & beans
      3. lentil soup & bread
RDA
1. increases with age
  1. men
    1. higher requirements
2. animal protein
  1. provides > RDA
3. vegan diets
  1. appropriate choices
    1. adequate protein
4. too much protein?
  1. adds calories
  2. stress liver
  3. increase urinary Ca2+
    1. osteoporosis
    2. calcium stones
Protein Malnutrition
1. Kwashiorkor
  1. older child
    1. when younger child born
  2. sufficient calories
    1. carbs
    2. low protein
    3. not starvation
      1. less muscle wasting
        greater impairment of protein synthesis
  3. infection
    1. increases protein requirements
    2. impaired immunoglobulin synthesis
      1. increased susceptibility to infectious disease
2. Marasmus
  1. starvation
    1. use ketone bodies and glucose
      1. spare aa
        availabilty for synthesis of albumin/other protein
3. Protein-Calorie Malnutrition
  1. spectrum
    1. simple starvation --> Kwashiorkor
    2. at risk
      1. children, elderly, hospitalized
4. Hypercatabolic states
  1. cause?
    1. trauma, surgery, infection, sepsis
  2. increases
    1. fuel utilization
    2. gluconeogenesis
    3. urea excretion
    4. muscle wasting
    5. circulating hormones/cytokines
  3. hyperglycemia
  4. negative N balance
    1. increase protein intake to minimize

Next up

Essential Amino Acids

Description

Resource summary

Similar

	Created by hardinbc about 11 years ago