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Protein & Amino Acids

Protein & Amino Acids . 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. Components of Protein. Peptide bonds: Amine and carboxyl groups Dipeptide Tripeptide Polypeptide

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Protein & Amino Acids

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  1. Protein & Amino Acids

  2. 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

  3. Components of Protein • Peptide bonds: • Amine and carboxyl groups • Dipeptide • Tripeptide • Polypeptide • Protein

  4. 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

  5. Leucine* Isoleucine* Valine* Histidine Lysine Methionine Phenylalanine Threonine Tryptophan Essential Amino Acids *Branched Chain Amino Acids

  6. Functions of Protein • Metabolism • Structure • Membranes • Cytoplasm • Muscle • Regulation • DNA • RNA • Hormones

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

  8. Protein Synthesis • Dietary protein  digestion  amino acids in blood • Cells use amino acids

  9. 120 g of free AA

  10. 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

  11. 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

  12. TCA Intermediates Pyruvate

  13. Gluconeogenesis • Glucogenic amino acids • Glucose-alanine cycle

  14. Factors Affecting PRO Req. • RDA • 7-14 yr: 1.0 g/kg • 15-18 yr: 0.9 g/kg • >18 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

  15. Characteristics of Skeletal Muscle • Comprises 40-45% of body weight • Contains 50% of total body protein • Composed of water & protein in 4:1 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

  16. Exercise and PRO Req. • PRO oxidation during exercise • Endurance • Resistance • PRO breakdown and synthesis during resistance training

  17. 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

  18. 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

  19. 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

  20. 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

  21. Potential Adverse Effects of High Protein Intake (>3 g/kg/day) • Increased saturated fats and cholesterol • Liver/kidney damage(?) especially if already exits • Ketosis • Dehydration (increase nitrogen) • Diabetic population • Urinary calcium • Performance

  22. PRO as an Ergogenic Aid • Amino Acids • Stimulate release of GH? • Stimulate release of insulin • Protein synthesis • Prevents fatigue • Prevent immuno-suppression

  23. 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

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

  25. 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

  26. Central Fatigue Hypothesis • Low glycogen and hypoglycemia  inc. gluconeogenesis • Inc. gluconeogenesis  dec. BCAA • High f-TRP and low BCAA (high f-TRP:BCAA ratio) • Increases f-TRP in brain  inc. serotonin  inc. sensation of fatigue

  27. 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

  28. High-Risk Groups • Gymnasts • Endurance Runners, especially females • Dancers especially ballet • Wrestlers, especially low weight-classes

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