1. Proteins Module 1.3
© 2013 Cengage

2. Amino Acid Structure Amino acids are the “building blocks” of protein
Amino acids contain nitrogen, carbon, oxygen & hydrogen; some contain sulfur.
Each compound has an amine group (NH2 contains nitrogen) at one end and an acid group (COOH) at the other with a distinctive side chain.
Peptide bond - connects one amino acid with another
Proteins are organic compounds
Each of the 22 amino acids has a different variable side chain
Amino acids combine together to make a protein
Amino Acids are categorized as essential or nonessential

3. Variation in Complexity
Composition
Size
Shape
Electrical Charge e
Side Chains

4. 9 Essential CANNOT be made by the body
Amino Acid Categories
12 Nonessential can be made from
nitrogen & CHO intermediates.
1 Non-Standard- not in humans *
Alanine
Arginine +
Asparagine +
Aspartic acid
Cysteine +
Glycine +
Glutamic acid
Glutamine +
Proline +
Tyrosine +
Serine +
Selenocysteine
Pyrrolysine *
+ can become essential in some cases
9 Essential CANNOT be made by the body
Histidine
Isoleucine
Leucine
Lysine
Methionine
Phenylalanine
Threonine
Tryptophan
Valine
Know these

5. Amino Acids “Trivia”
The distinction between essential and non-essential amino acids is somewhat unclear, as some amino acids can be produced from others.
For example the sulfur-containing amino acids, methionine and homocysteine, can be converted into each other but neither can be synthesized de novo in humans.
Only the female mosquitoes bite people. They are searching for essential amino acid isoleucine
Non-essential tyrosine can be synthesized from phenylalanine
Phenylalanine is thought to act as a pain reliever.
Recent studies show Lysine to be effective against herpes by improving the balance of nutrients that reduce viral growth.

6. Protein Categories High *Biological Value
High Quality proteins contain all the essential amino acids, and are high biological value proteins or complete proteins.
Complete Proteins come from animal sources such as: milk, yogurt, meats, eggs, and cheese.
Low Biological Value
Low Quality Proteins: Lack one or more essential amino acids, and are low biological value proteins or incomplete proteins.
Incomplete Proteins are plant sources of proteins such as: vegetables, legumes (dried beans), nuts, seeds, tofu, and grains.
*Biological value = measure of the proportion of absorbed protein from a food and the amounts of the essential amino acids present in the protein.

7. Complementary Protein
Low quality protein sources can be combined in such a way that the essential amino acids that are limiting in one protein are supplied by another protein.
The combined proteins can provide all of the essential amino acids of a high quality protein source.
Examples: peanut butter/bread; beans/tortilla; rice/vegetables

8. Protein Complementation
Grains
Legumes
Nuts & Seeds
Vegetables
Food Combinations
Combine any 2 food groups for complementation

10. Protein Functions Growth and maintenance Body structures
Regulatory Roles
Enzyme action
Hormones
Antibodies
Oxygen and carbon dioxide transport
Fluid balance (Albumin)
Acid-Base Balance
(alkalosis, acidosis, buffers)
Transport Proteins
(sodium/potassium pump; lipoproteins)
Energy Production
Antibodies

11. Acid/Base Balance
pH 14
Basic
Normal
H+ H+ H+ H+ H+ H+
H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+
pH Values of Selected Fluids
A fluid’s acidity or alkalinity is measured in pH units. Alkalosis is a condition in which the body fluids have excess base (alkali). This is the opposite of excess acid called acidosis.
pH: the concentration of hydrogen ions. The lower the pH, the stronger the acid, the higher concentration of hydrogen ions (H+)
pH 2 is a strong acid,
pH 7 is neutral, and
pH above 7 is alkaline.
pH 0 - Acidic

12. Protein as a Source of Energy
Copyright 2010, John Wiley & Sons, Inc. 12

13. Protein Processes
Denaturation -the change in shape of a protein can be caused by heat, mechanical agitation, alcohol, acids, bases, salts of heavy metals
Configuration:
primary
secondary
tertiary
quaternary

14. Protein Dietary Recommendations
based on body weight.
The adult DRI for protein is *0.8 grams of high quality dietary protein per kilogram body weight per day.
10-35% of calories should come from protein (this is the AMDR).
Average US intake 55% - Meat / Beans Group
Average US intake 36% - Milk and Grains Group
*Dietetic recommendations approximate g/kg
Too Much Protein
Can overload to the liver and kidneys.
Increase calcium excretion.
Stored as body fat increased risk of obesity
Increase demand of B6

15. Protein Calculations
0.8 grams per kilogram of desirable body weight per day.
Convert pounds to kilograms (divide pounds by 2.2 lbs = l kg) = Ex: 150 lb /2.2 = 68 kg
68 kg x 0.8g = 54.4 g of protein per day