2. Chemistry
Composition: C H O N (S)
Amino Acids “building blocks”
– Amine group (NH2)
– Acid group (COOH)
– Differ by side group (“R”)
9 : from food
11 Nonessential AA: can be made from other
AA
3. Amino Acid, Peptide Protein
Amino acid
NH2
R C COOH
Peptide and protein
AA1-AA2-AA3-AA4--- AAn
4. Digestion Absorption
HCl
Enzymes split long chain of AA for
absorption
Blood transports AA to liver muscle
5. Functions of Protein
Growth, build maintenance of tissues
Regulate body processes:
Water (fluid) balance--prevent edema
Acid-Base (pH)
balance--buffers Immune
system - antibodies
Energy source--4 calories / gram
6. Protein Synthesis
DNA code controls : Which AA needed
What order AA go on new chain
AA3
AA1 + AA2AA1AA2 AA1AA2AA3
Requires:
Calories
Essential AA from AA pool
Non-essential AA from synthesis or diet
7. Process of Protein Synthesis
DNA ------RNA ---- Protein
Transcription Translation
DNA=deoxyribonucleic acid
RNA=ribonucleic acid
8. Catabolism of Protein
Breakdown of protein to AA
AA converted to fat when
excess AA
N from AA is reused for AA synthesis;
excess is excreted in urine
–May cause loss of Ca in urine
–Kidney disease problem
9. Protein Quality
Complete Protein
High quality
All essential AA in
needed amounts
Animal sources
Incomplete Protein
Plant sources
70% of protein from
animal sources in US
10. Complementary Protein
Plant protein
(legume) with
limiting AA
combined with
different plant
protein (grain)
different limiting AA
eaten together give
complete protein
11. Plants provide Incomplete
Protein
Low in one or
more ess. AA
Eat in combo
to “complete”
the AA
balance
12. Protein Requirements
.8 gm/kg body weight
Protein RDA
46 gm for women
58 gm for men
10-12% kcal from protein
Actual US Intake
80 gm
110 gm
~17% kcal from protein
13. Food Sources of Proteins
Meat
Fish
Poultry
Eggs
Beef pork rich in
iron but high in
fat
14. More Good Protein Sources
Dairy products
select low fat
(butter not protein)
Legumes
Cereal grains
Seeds
Nuts
Plant sources of
protein are low in
fat
15.
16. What about protein for
athletes? Athlete needs 1.26 gm /
Kg (~90 gm)
(but typical US male
eats 110 gm and
female eats 80 gm)
Thus… supplements
not needed
What does the body do
with the added amino
acid?
What builds muscle:
exercise and a good
diet
17. Amino Acid Supplement
High intake of a single AA leads to AA
imbalance and is harmful
Many AA supplements on market,
Surplus of AA causes diarrhea, loss of
appetite, GI upsets
Tryptophan supplements were banned
in 1990
Athletes
18. Vegetarian Diets
Semi-vegetarian:
– lacto vegetarian
– ovo vegetarian
Strict vegetarian:
– “Vegan”
– healthy diets use complementary proteins
Macrobiotic diet: locally grown and whole
foods; Yin(“cold”)yang(“warm”) foods
19. Vegetarian Diets Health
Associated with low risk of chronic
diseases
May lead to
Vegans: vitamins B12 and D, Ca, Zn are
at risk
Adequately planned vegetarian diets
can
The key to achieve healthy diet: variety
20. Protein deficiency--Marasmus
Chronic food
deprivation,diseases
Protein calories
Impairs brain
development
learning
Severe weight loss
Infection, diarrhea
21. Protein deficiency
--Kwashiorkor
Deficiency in protein but
not calories
Children 1-3 years
Some weight loss
Edema
Hair: dry, brittle,
changes color (lack of
AA to make melanin)
