PROTEIN

Somatic Protein: Function

Cellular growth, maintenance. Hormones Acid base regulation Water regulation Enzymes Transporters Antibodies Neurotransmitters

Dietary Protein: Function

Use only for the previous functions Energy. Protein is used for energy when

Glycogen and fat stores are low (starvation). Rigorous, continuous exercise (ultramarathon). When carbohydrate intake is inadequate. When caloric intake is inadequate.

Your body uses protein as energy as a LAST resort to give your brain glucose. Using protein as an energy source is called “amino acid wasting.”

Dietary Protein Requirements

For inactive individuals, RDA is .8g per kg For moderately active individuals 1g per kg For very active individuals (training athletes)

the requirement is 1.2 - 2g per kg depending on type of exercise.

The average woman should consume 50g per day.

The average man should consume about 60g per day.

Calculate your dietary protein intake.

Amino Acids Amino acids. Are the building blocks of a

protein. Types

Essential. Cannot be made by the body. Must be consumed in food products (plant and animal).

Non-essential. Can be made by the body from other amino acids, or fats, carbohydrate and N.

Conditionally essential. Is dependent upon the intake and complete conversion of the essential amino acid that is its precursor.

Chemical Structure of an Amino Acid

How Amino Acids Compare

Protein Synthesis Proteins are made by condensation of amino

acids together.

Protein Synthesis Protein Synthesis starts in the nucleus Production of a protein actually occurs on a

ribosome of the rough endoplasmic reticulum in each cell.

Structure Dictates Function

For a protein to function correctly all following criteria have to be met: All amino acids have to be present. Amino acids must be in the correct sequence as

dictated by DNA/MRNA instructions. Protein has to be in the correct structure with

other compounds that are necessary. If all the following criteria is not met, the protein

will either not be made, or the protein will not function properly.

Human Insulin: Amino Acid Sequence

Protein Denaturation Proteins can be metabolized, destroyed or rendered

dysfunctional by denaturing. Components of denaturing

Heat PH changes Extreme pressure Detergents and caustic solvents (bleach)

Denaturing DIETARY protein will not affect it’s protein content.

Denaturing SOMATIC proteins (fever, altered blood PH) can adversely affect body functions

Protein Quality Complete Protein: Contains all the amino acids

in the proportion that humans require. Ex: all meats and dairy products. Soy is close.

Incomplete Protein: Does not contain all essential amino acids. Ex: grains, vegetables, legumes.

Mutual supplementation: Eating two complimentary proteins together as to supply all the amino acids

Complimentary proteins. Food products which have amino acid profiles that compliment each other.

Legumes

Nuts and seeds

Grains

LegumesVegetables

Evaluation of Protein Quality

PDCAAS. Protein Digestibility Corrected Amino Acid Scoring.

PDCAAS are used to evaluate protein quality in many food products.

To attain a score, the protein’s amino acid profile is compared against the amino acid requirements of preschool aged children and then corrected for digestibility. (Biological Value)

Digestibility (Biological Value) is established by nitrogen retention studies conducted on humans.

Protein Turnover Nitrogen Balance: Nitrogen IN vs Nitrogen OUT

Nitrogen equilibrium Positive nitrogen balance Negative nitrogen balance

Deamination. The breaking off of nitrogen group so the remaining parts can be used for making non-essential amino acids, other proteins, glucose, fat, and neurotransmitters. A constant process in the liver. Ammonia is produced.

Transamination. The transfer of the nitrogen group from one amino acid to a keto acid producing a new amino acid and a free keto acid. This process does not create ammonia.

Under consumption of protein.

PEM. Protein-Energy Malnutrition Marasmus. Starvation Kwashiorkor. Protein malnutrition

Both have similar and very different symptoms (look in text). However, both are harmful and eventually cause death if left untreated.

For the average person, low protein can cause muscle wasting, fatigue, poor injury recovery, edema, and compromise the immune system.

Over consumption of protein

Human body can handle 350 grams or more of protein without harmful effects as long as the nitrogen is being used.

If nitrogen is not being used: Increased urination to rid excess nitrogen Increased kidney and liver work load Excess excretion of nitrogen may affect bone

calcium. Increased urination can lead to dehydration Use of single amino acids is not advised.

Vegetarianism Chosen for religious, ethical, aesthetic, or

experimental reasons. Three types:

Ovo-Lactovegetarian: Will eat eggs and dairy Lactovegetarian: Will eat dairy products only Vegan: Will NOT eat ANY animal derived products.

“Semi-Vegetarians” are NOT true vegetarians Vegans must use mutual supplementation or

soybean products to fulfill protein needs. Vegans must take D and B12 supplements or

received them from fortified foods. Vegans must be mindful to eat a varied diet to

receive calcium, iron, and zinc.

Protein Quiz

1. Element found in protein, but not in carbohydrate or fat.

a. Carbon b. Hydrogen c. Nitrogen d. Oxygen

2. The building blocks of protein

a. Keto acids b. Amino acids c. Ammonia d. glyercol

3. The unraveling of a protein’s structure due to heat, acid, alkalinity or pressure.

a. Denaturation b. Condensation c. Trans-amination

4. Incomplete proteins that complete each others amino acid profiles.

a. mutual b. essential c. complimentary d. PDCAAS

5. During construction of a specific protein, the body will replace a missing amino acid with another that is readily available True or False?

6. Extra Credit: Identify 1 essential amino acid.