1. Kin 110 Lecture 5
Ch. 6 Proteins

2. Overview of Proteins
Thousands of substances in body are make of protein
Major non-water component of lean tissue (16 %)
20 different amino acids
building blocks of protein
9 essential - must be obtained from diet
Complete protein
high quality - all essential a.a.
Incomplete protein
lower quality - lack sufficient amount of one or more essential a.a.
simple combinations - complementary

3. Overview of Protein Proteins crucial for thousands of body processes
each function requires specific protein
sequence of a.a. determines structure and function
body uses a.a. form diet as building blocks for many configurations and sizes of proteins for these varied functions
without proper essential a.a. in diet, body functions slow, immune system begins to fail

4. Amino Acids Amino acids have general structure
variations in ‘R’ region determine functional characteristics (p. 176)
20 a.a. - 9 essential - can not be made by the body
Table 6-1, p 177
Physiologically essential
PKU - Phenylketonuria
inability to process phenylalanine (ess.) into tyrosine (non-ess.)
Tyrosine becomes an ess. a.a.

5. Dietary Considerations (ess. vs. non-ess.)
Complete protein
contains all 9 ess a.a.
Animal and Soy protein
Incomplete protein
lacks one or more ess a.a.
most plant proteins
Important as all a.a. are necessary for protein synthesis
All or None Principle of protein synthesis
ALABAMA eg.

6. Complementary Proteins
Various plant sources can compensate for ess a.a. deficiencies
Adults should have little concern, combination over entire day is important
more attention required for young children
Fig. 6-2, p 179
* know traditional combinations that make complete protein in diet *

7. Protein Amino acids joined by peptide bonds
thousands of different proteins
Letters making sentences, paragraphs
order directed by DNA, genes
Creates specific and unique 3-D structure, necessary for functioning
Eg. Sickle cell anemia

8. Denaturing of Protein Acid, alkaline, Heat or agitation
alters protein 3-D structure
destroys normal function
Cooking, makes foods safer to eat and facilitates further digestion (exposure to enzymes)
* recall - we dismantle proteins for the a.a. building blocks*

9. Digestion and Absorption
Begins in stomach
Enzyme Pepsin
breaks proteins into smaller a.a. sequences (selected bonds)
Creates Peptones
Hormone Gastrin controls release of Pepsin and Acid
acid activates pepsin and denatures proteins

10. S.I. And Protein
Protein and Fat in SI trigger pancreatic juice to be released
Divides peptones into smaller sequences
Broken into a.a. and short sequences for absorption
travel to liver (portal circulation)
recombined into protein
converted to glucose or fat
released to blood

11. Functions of Proteins
To ensure availability of ingested protein for these functions, you must take in sufficient carbohydrates and fat for energy needs
Vital body constituents
most are in a constant state of breakdown , rebuilding and repair
most a.a. can be recycled, by some are lost, requiring constant intake in small amounts.

12. Other Protein Functions
Fluid balance
Blood Proteins
albumin and globulins bring fluid back into the bloodstream after in leaves at the capillaries
prevent edema (swelling)
Acid Base Balance
proteins in membranes pump ions in an out
buffers; take away and add acid (H+) as required

13. Other Protein Functions
Hormones, Enzymes and Neurotransmitters
Immune Functions
Antibodies
Rapid production requires ample protein availability
excess protein does not boost immune function
Formation of glucose and Fat
Provision of Energy
costly processing

14. Protein Intake Protein equilibrium need to balance intake with output
output measure as nitrogen in urine (protein broken down)
fig 6-6 p 189
Positive balance - required for growth, recovery from illness, training
requires insulin, growth hormone, testosterone
Negative balance - occurs with inadequate intake, infections, bed rest

15. RNI for Protein .8 g/Kg healthy body weight double for infants
56 g for 155 lb man
44 g for 120 lb woman
2-3 servings per day
Table 6-3 p 191
mental stress and physical labor do not increase requirement
World class athletes may benefit from up to 1.5 g /Kg
Pregnancy inc. need by 10-15g
elderly may have higher needs

16. High Protein Diet? Increased saturated fat intake, lower fiber intake
May increase loss of calcium
may relate to colon cancer
may accentuate heart disease
homocysteine
Recommended not to exceed 2 X RNI
whole foods NOT supplements
average diet already X RNI
athlete diet already larger, take in more protein with balanced diet

17. Protein Source Animal - most dense source 65 % animal protein in US
20 % in Africa, parts of Asia
Plant sources - complementary
high in Magnesium and Fiber
no cholesterol and little saturated fat

18. Vegetarianism Why ? Political, Ecological, Health reasons soy protein
lowers LDL
antioxidant
vascular dilation
Vegan - only plant foods
Lacto-vegetarian - plant and dairy
Lacto-ovo vegetarian - plants, dairy and eggs
Omnivore - both plant and animal
Concerns - essential a.a., essential fatty acids, vitamin B-12, calcium