1. The Macronutrients-Proteins
Chapter 1

2.                                                                            
p ,000 different protein containing compounds in body, each depends on sequence of amino acids

3. Overview of Protein Body is made up of thousands of protein substances
More than 30,000 different kinds of protein
Unique structure and function
Twenty amino acids commonly found in human protein
Proteins = 50% of the dry weight of most cells

4. Overview of Protein Made up of amino acids
Contains carbon, hydrogen, and oxygen
And at least one N in structures
N is in the form of an amine group (NH2)
Carboxyl group (COOH)
R group: side chain, this is what makes each amino acid unique

5. Amino Acid R group Acid group Nitrogen group NH2 O R C C OH H
Amine group-+ charge; organic acid-COOH -; side chain R that is the functional group. side chain’s unique structure dictates amino acid’s characteristics
R group Acid group
Nitrogen group

7. Overview of Proteins Amino acids Peptide bonds
Dipeptide – two amino acids
Tripeptide – three amino acids
Polypeptides – multiple amino acids

9. Protein Organization Polypeptide chain
Twists and bends to native conformation
Determined by side chains
Hydrophilic – outer surface
Hyrophobic - folded inside

10. Proteins Order of amino acids Final shape Determines shape
Determines function
Determines stability

11. Fig a
02.16a.jpg

12. Hemoglobin 4 associated polypeptide chains, each holding iron

13. Proteins Denaturation Uncoiling – alters function Heat Stomach acid
Irreversible
After certain point, denaturation cannot be reversed.

14. Denaturation of Proteins

15. Denaturation Foods are a means of obtaining amino acids
Cooking can make substances available
Vitamin – biotin (cooked eggs)

16. Denaturation of Proteins
Heat/acid/alkaline/enzymes
Results in alteration of the protein’s three
dimensional structure

17. Overview of Protein Amino acids-20 required by body
Essential – indispensable
Body does not have pathway to synthesize
Supplied by diet
Non-essential
Can be provided through metabolic pathways
Conditionally essential amino acids
Under certain conditions
Typically malnutrition

18. Dietary Protein Animal proteins Low-quality High-quality
Complete – 8 essential amino acids
Low-quality
Incomplete
Lacks one or more essential amino acids
Most plant foods
Cannot meet all amino acid needs
Greater variety and amount of plant proteins needed
9 in children

19. Transamination Transfer of an amine group Formation of new amino acid
From a donor amino acid
To an acceptor amino acid
Formation of new amino acid
Through process of transamination.

20. Dietary Protein All-or-none principle in protein synthesis
If not all of the amino acids are present, protein synthesis does not occur
Limiting amino acids
Essential amino acid in smallest supply
Complementary proteins
Mixed diets – foods containing different amino acids are combined

21. Limiting Amino Acid CCCCC AAAAAAAA CAR CAR CAR RRRRRR CAR CAR R A A A
C is the limiting amino acid in this example
CCCCC AAAAAAAA CAR CAR CAR RRRRRR CAR CAR R A A A

22. Complementary Protein
Food 1 Food 2 Combined CC CCCC AAAA AA CAR CAR CAR RRR RRR CAR CAR CAR

23. Vegetarians Protein requirements
Variety of plant foods - Complementary
Grains and legumes
Soy protein
Lacto vegetarian
Milk, milk products
Ovolactovegetarian
Eggs
include alfalfa, clover, peas, beans, lentils, lupins, mesquite, carob, and peanuts.
Grains lack lysine but have methionine; soy protein may be as good a quality as animal
Beans and rice, rice and lentils – complementary
Vegans, no meat or dairy, lacto ovo - eggs

24. Protein Sedentary 0.8-1.0 g/kg/d Recreational exercisers 0.8-1.0
Serious RT, early
Serious RT, established
Serious endurance
Adolescent athlete
Definitive answer still unclear, some protein breakdown during intense endurance as well as resistance training
Animal vs plant protein-

25. Role of Proteins Protein content of skeletal muscle
65% total protein of body
Component of tissue structures
Cells
RNA, DNA
Electron carriers
NAD, FAD 38

26. Structural Proteins
Keratin. Hair, skin, nails, bones, tendons.

27. Structural Proteins

28. Globular Proteins
Enzymes are globular proteins, 2000 different enzymes regulate reactions in body such as breakdown of fats, CHO, Pro

29. Protein Turnover Replenishment of protein containing structures
Amino acid pool
Anabolism
Tissue building
Catabolism
Tissue breakdown

30. Nitrogen Balance Positive nitrogen balance Negative nitrogen balance
Intake exceeds excretion
Synthesis of new tissues
Negative nitrogen balance
Protein used for energy
Uses reserves – skeletal muscle
Reserves from skeletal muscle, starvation, reduced CHO or kcals can trigger protein deficiency.

31. Protein Metabolism Deamination Fate of deaminated carbon compound
Releases amine group
Urea
Fate of deaminated carbon compound
Make new aa
Converted to CHO or fat
Catabolized for energy
Nitrogen is released which forms urea which promotes fluid loss due to water needed to dilute urea

32. Additional Roles of Protein
Nervous and connective tissue
Not in energy metabolism
Alanine provides CHO fuel
Gluconeogenesis – prolonged exercise
Alanine-glucose cycle provides 40-50%
From liver’s glucose release
Provide up to 15% of the total energy requirement
Muscle proteins easier to break down when energy needed
Alanine may be energy source
After 4 h continuous exercise, alanine from liver accounts for 45% of liver’s total glucose release