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 Protein

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

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

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

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

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

120 g of free AA

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

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

TCA Intermediates Pyruvate

Gluconeogenesis Glucogenic amino acids Glucose-alanine cycle

Factors Affecting PRO Req. 1. RDA 7-14 yr: 1.0 g/kg 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

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

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

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 g/kg

PRO and Strength Training Resistance training  PRO breakdown Resistance training does not increase protein oxidation significantly Next hrs.  protein anabolism Also needed for recovery/repair Eccentric Recommendation is g/kg

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 kcal/day to support additional tissue growth

How much is 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

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

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

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

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

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

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

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

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