Protein & Amino Acids. Components of Protein Amino acid chains (up to 300 AA) Amino acid...

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 synthesis2. Protein degradation3. Amino acid oxidation4. 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 Intermediates2. 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 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 nursing4. Disease, infection, trauma5. 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 1.2-1.8 g/kg

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

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

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

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