Protein

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Protein Amino Acids
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Components of Protein

• Amino acid chains (up to 300 AA)
• Amino acid consists of
• 1. Amine group (NH3)
• 2. Hydrogen
• 3. Carboxyl group (COO-)
• 4. R side chain

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Components of Protein

• Peptide bonds
• Amine and carboxyl groups
• Dipeptide
• Tripeptide
• Polypeptide
• Protein

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Components of Protein

• Twenty different amino acids
• Essential (9) nonessential (11)
• Complete vs. noncomplete protein
• Animal vs. vegetable
• Complementary proteins
• Beans Rice
• Beans Corn or Wheat
• Peanut butter Bread

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Essential Amino Acids

• Leucine
• Isoleucine
• Valine
• Histidine
• Lysine

• Methionine
• Phenylalanine
• Threonine
• Tryptophan

Branched Chain Amino Acids
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Functions of Protein

• Metabolism
• Structure
• Membranes
• Cytoplasm
• Muscle
• Regulation
• DNA
• RNA
• Hormones

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Protein Metabolism

• Four components
• 1. Protein synthesis
• 2. Protein degradation
• 3. Amino acid oxidation
• 4. Gluconeogenesis

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Protein Synthesis

• Dietary protein ? digestion ? amino acids in
  blood
• Cells use amino acids

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120 g of free AA
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Protein Degradation

• Cells break down
• Protein not stored
• Removal of catabolized PRO needed
• Blood ? liver (deamination)
• Excreted as urea
• Converted to fat or CHO
• Oxidized as energy

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Amino Acid Oxidation

• Amino acids can be metabolized for ATP
• Amine group must be removed
• Two ways
• 1. Deamination
• -Urea and Krebs Cycle Intermediates
• 2. Transamination
• -Krebs Cycle intermediates
• -Pyruvate ? acetyl CoA

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TCA Intermediates Pyruvate
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Gluconeogenesis

• Glucogenic amino acids
• Glucose-alanine cycle

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Factors Affecting PRO Req.

• RDA
• 7-14 yr 1.0 g/kg
• 15-18 yr 0.9 g/kg
• gt18 yr 0.8 g/kg
• 2. Total energy intake
• As energy inc., PRO req. as decreases
• 3. Pregnancy and nursing
• 4. Disease, infection, trauma
• 5. Exercise

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Characteristics of Skeletal Muscle

• Comprises 40-45 of body weight
• Contains 50 of total body protein
• Composed of water protein in 41 ratio
• Body protein turns over at 3-4 g/kg/day
• Skeletal muscle turns over at 1 g/kg/day
• Skeletal muscle is 25 of total turnover

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Exercise and PRO Req.

• PRO oxidation during exercise
• Endurance
• Resistance
• PRO breakdown and synthesis during resistance
  training

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PRO Oxidation During Exercise

• Endurance training ? Inc. muscle mitochondrial
  protein enzymes (leucine oxidation)
• Typically 5-15 of resting metabolism
• Prolonged endurance 10 max
• Depletion of glycogen
• Protein not from contractile protein
• Recommendation is 1.2-1.8 g/kg

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PRO and Strength Training

• Resistance training ? PRO breakdown
• Resistance training does not increase protein
  oxidation significantly
• Next 24-48 hrs. ? protein anabolism
• Also needed for recovery/repair
• Eccentric
• Recommendation is 1.6-1.7 g/kg

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Protein and Muscle Anabolism

• 1 lb muscle contains 100 g protein (22)
• Reasonable muscle gain is 1 lb/week
• Additional 14 g per day protein or 0.14 g per kg
  for 100 kg individual
• 400-500 kcal/day to support additional tissue
  growth

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How much is 70-90 g of PRO?

• 6 oz. Chicken breast 48 g
• 1 cup skim milk 8 g
• ½ cup peanuts 18 g
• 2 oz. Cheddar cheese 14 g
• Grand total 88 g

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Potential Adverse Effects of High Protein Intake
(gt3 g/kg/day)

• Increased saturated fats and cholesterol
• Liver/kidney damage(?) especially if already
  exits
• Ketosis
• Dehydration (increase nitrogen)
• Diabetic population
• Urinary calcium
• Performance

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PRO as an Ergogenic Aid

• Amino Acids
• Stimulate release of GH?
• Stimulate release of insulin
• Protein synthesis
• Prevents fatigue
• Prevent immuno-suppression

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Arginine, Lysine, Ornithine

• Increases GH (30 g/30 min)
• Increases insulin (but not as much as CHO
  ingestion)
• Does it work?
• Tolerable oral doses (1-2 g/day) have less effect
  than exercise
• Large oral doses cause severe GI disturbances

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Aspartate

• Improve aerobic capacity?
• Precursor to TCA intermediates and reduces plasma
  ammonia (cause of fatigue)?
• No effect shown in controlled studies

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Branched-Chain Amino Acids

• Leucine, isoleucine, valine (essential AA)
• Oxidized during exercise
• Oral administration can spare protein?
• CHO is better source to spare protein
• Oral administration can reduce fatigue?
• Reduces serotonin levels in brain to reduce
  fatigue.
• No support in controlled studies

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Central Fatigue Hypothesis

• Low glycogen and hypoglycemia ? inc.
  gluconeogenesis
• Inc. gluconeogenesis ? dec. BCAA
• High f-TRP and low BCAA (high f-TRPBCAA ratio)
• Increases f-TRP in brain ? inc. serotonin ? inc.
  sensation of fatigue

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Glutamine

• Proposed effects
• Improved hydration?
• Improved immune system?
• Improved muscle synthesis?
• Stimulation of glycogen resynthesis?
• Reduction in muscle soreness and improved tissue
  repair?
• Controlled studies have not shown documented
  effects

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High-Risk Groups

• Gymnasts
• Endurance Runners, especially females
• Dancers especially ballet
• Wrestlers, especially low weight-classes