proteins enzymes, hormones, and body building lecture 4 february 2, 2015 dr. ponnusamy

PROTEINS

Enzymes, Hormones, and Body Building

Lecture 4February 2, 2015Dr. Ponnusamy

Department of Food Science

Lecture 4: February 2, 2015

Instructors’ Contact

• Dr. Loredana Quadro Food Science Department, Room 419 Office hours: Thursday 2:30-4:30 pm (no office hours

Feb 5, 2015)

[email protected]

• Dr. Chitra Ponnusamy [email protected]

• Dr. Mary Wasserman [email protected]

mailto:[email protected]





Six Classes of Nutrients

1. Carbohydrate- macronutrient; yields energy

2. Fats- macronutrient; yields energy

3. Proteins- macronutrient; yields energy

4. Vitamins - micronutrient

5. Minerals - micronutrient

6. Water- macronutrient; no energy



The word “protein”

Derived from the Greek word proteios, which means “of the first rank”

Coined by Jon BerzeliusSwedish chemist

discovered that an extract of potatoes is more effective than concentrated sulfuric acid in promoting the breakdown of starch



Sources of Protein in the Diet

• In the US, about two-thirds of dietary protein comes from meat, poultry, seafood, eggs and dairy products.

• Most of the world relies on plant proteins from grains, legumes and vegetables.

• As a country’s economy improves, the proportion of animal foods in the diet tends to increase.

• Protein deficiency is rare in the United States.



Functions of Body Proteins

• No living tissue can be built without protein

• Protein is part of every living cell

• Proteins account for ~ 20% of body weight

• Proteins come in many forms

• Proteins perform many vital functions

Body proteins are not static; they undergo constant breakdown and are resynthesized. This process is called protein turnover.



• Protein is very critical in the regulation of human metabolism. It is used to form muscle, connective tissue,

blood clotting factors, blood transport proteins, lipoproteins, visual pigments, and the protein matrix inside the bones.

Lipoproteins help transport lipids in the body.



• Protein is also used to maintain the body fluid balance by producing albumin and globulin. Without

sufficient protein in the blood stream, edema would quickly develop.



• Dietary protein also contributes to the acid-base balance by producing buffers that help regulate the

amount of free hydrogen ions in the blood. This accepting or donating of hydrogen ions helps to keep the blood pH slightly alkaline (pH 7.35 to 7.45).



• The immune system is also composed of proteins. Antibodies are proteins. Without enough

dietary protein, the immune system will lack the cells needed to function properly, thus energy or the lack of an immune response can appear.



• ENERGY SPARING ACTION OF PROTEINS:

Dietary protein can also be used as an energy source . If a diet does not contain enough carbohydrate to supply needed glucose, proteins can be used to synthesize glucose.



PROTEINS THUS FUNCTION AS:

Enzymes – over 2000 – necessary for digestion and catalase reactions

Hormones – regulate metabolic reactions• Examples: insulin and adrenaline

Immune functions• antibodies (immunoglobulins)



• Transport and Storage proteins hemoglobin, myoglobin, lipoproteins

• Structural proteins for Mechanical Support keratin, collagen, elastin Examples of body structures include skin, hair, nails,

membranes, muscles, teeth, bones, organs, ligaments and tendons.

• Contractile -Muscle proteins myosin, actin, tubulin

Protein, along with calcium is necessary to maintain bone mass and prevent fractures!



Protein As Energy

• In the absence of adequate energy, the body will sacrifice protein to provide energy

• The amine group will be degraded (DEAMINATION), incorporated by the liver into urea, and sent to the kidneys for excretion in urine (urea: the principal nitrogen excretion product of metabolism)

Energy from proteins: 4 Calories per gram



Proteins are made of Amino Acids (building block of proteins)Amino acids differentiate proteins: Each amino acid has an

amino group, an acid group, a hydrogen atom, and a side

group (R-group)

R-CH-NH2-COOH

R-group differentiates the amino acids from each other

Nitrogen differentiates proteins from carbs and fat



Protein

20 Amino Acids + 3D Structures

> 100,000 different proteins

Different protein structures are formed from amino acids owing to:variations in number, proportion and order of amino acids



Amino Acids 20 total amino acids 9 are essential Remaining 11 can be

synthesized by body (non-essential)

ESSENTIAL AMINO ACIDS MUST BE SUPPLIED BY THE DIET

NONESSENTIAL AMINO ACIDS ARE THE ONES THE BODY CAN CREATE

O OCCNH

H

H H+

--

SIDEGROUP



9 ESSENTIAL AMINO ACIDS

1. HISTIDINE 6.PHENYLALANINE

2. ISOLEUCINE 7. THREONINE

3. LEUCINE 8. TRYPTOPHAN

4. LYSINE 9. VALINE

5. METHIONINE



11 NONESSENTIAL AMINO ACIDS

• Human body has the capability of synthesizing the 11 nonessential amino acids.

• When these amino acids are in short supply transamination or the transfer of an amine group (nitrogen group) from an amino acid to a carbon skeleton to form a new amino acid takes place.



Copyright 2010, John Wiley & Sons, Inc.

Protein Structure

• Peptide bonds are chemical bonds that link amino acids together.

• Peptide bonds are formed between the acid group of one amino acid and the nitrogen group of the next amino acid.

• Dipeptide bonds are formed between two amino acids.

• Polypeptides are formed between many amino acids.

• A protein is made of one or more polypeptide chains folded into a three-dimensional shape.




Protein Structure



PEPTIDE BONDS

• AMINO ACID CHAINS ARE LINKED TOGETHER BY PEPTIDE BOND

• 2 AA= DIPEPTIDE

• 3 AA= TRIPEPTIDE

• MULTIPLE AMINO ACIDS= POLYPEPTIDE

• FOODS CONTAIN POLYPEPTIDES



Insulin : an example of multiple amino acids linked into a protein chain

http://www.chem.uwec.edu/Chem406/Webpages/Ying/overview.htm

Porcine Pro-Insulin:● 3 chains● 74 amino acids

Human and Bovine Insulin:● 2 chains● 51 amino acids



Recommended Protein IntakesRecommended protein intakes can be stated by two

methods. As a percentage of total calories:

• Protein should provide 10-35% of total calories As an absolute number (grams per day).

• A healthy adult should consume 0.8 gram per kilogram of desirable body weight per day

• Calculation:

Weight: 150 pounds = 68 Kg (150/2.2)

Grams protein: 68 x 0.8 = 54g protein



Increased protein needs

• Growth

• Illnesses

• Injuries

• Pregnancy

• Lactation

Nitrogen Balance



Nitrogen Balance

• The term "nitrogen balance" refers to the amount of nitrogen the body excretes, as opposed to the amount of nitrogen the body takes in.

• All of the macronutrients — protein, carbohydrate, and fat — are made up of carbon, hydrogen, and oxygen molecules.



• Protein alone also contains an additional nitrogen molecule. When the body digests protein, these nitrogen molecules are generally released into the blood.

• Measuring body nitrogen levels can be the most accurate way to determine whether the body is receiving adequate, inadequate, or excess protein.



Nitrogen Balance

• a determination made about the body's ability to meet its protein needs which is reached by comparing the amount of nitrogen taken in with the amount discharged via urine, hair, skin, or perspiration.



Negative nitrogen balance

• A body condition in which nitrogen output exceeds nitrogen intake

• Reflects on the body's need to draw on its own stores of protein for energy

• may be caused by dietary imbalances, illness, infection, anxiety, or stress.



Positive Nitrogen Balance

• a body condition in which nitrogen intake exceeds nitrogen output;

• a normal state for children, pregnant women, or individuals recovering from illness or surgery

• These individuals require extra protein in order to build tissue.

• Excess protein can also help athletes and body builders recover faster from workouts.




Nitrogen Balance



Protein Source Consumption




• Animal products provide sources of protein, B vitamins and minerals such as iron, zinc and calcium.

• However, animal products are low in fiber and can be high in fat.

• Plant sources of protein are also a good source of B vitamins, iron, zinc, fiber and calcium, but in less absorbable forms.



Protein Quality: based on essential amino acids

• Complete Protein: Needed for growth

• Proteins from animal foods are 90-99% absorbed Contain all the essential amino acids in the

right proportion• Milk, Meat, Eggs

Soy is the only plant source of complete protein.



• Partially Complete Protein

Lacking or low in one or more of the essential amino acids

Plant proteins are 70-90% absorbed

• Example: Gliadin protein of wheat



• Limiting Amino Acid- the missing essential amino acid Essential amino acid in shortest supply

(relative to the body’s need) in a food protein

limits the body’s ability to make its own proteins

.



HIGH QUALITY PROTEINS

• ANIMAL FOODS - CONTAIN ALL ESSENTIAL AMINO ACIDS; HENCE TERMED HIGH QUALITY PROTEINS EGG WHITE PROTEIN- BIOLOGICAL VALUE 1.0;

REFERENCE PROTEIN CASEIN- MILK PROTEIN- A COMPLETE PROTEIN

• PLANT FOODS – TEND TO MISS ONE OR MORE ESSENTIAL AMINO ACIDS

Except: SOY Protein- Complete with 9 essential amino acids



Protein Quality of Foods

Complementary proteins

two or more food proteins whose amino acid assortments complement each other in such a way that the essential amino acids limited in or missing from each are supplied by the others.



AA Limiting Proteins

FOOD LIMITING AMINO ACID

Rice lysine

Corn lysine

Wheat lysine

Legume (beans) methionine

Mutual complementation: complementary proteins supply all the essential amino acids; an important consideration for vegetarians

Vegetarian diets include animal products, like dairy.



Protein Quality – PB&J example

√

√

√ √




Meeting Protein Needs with a Vegan Diet

Grains and legumes are considered good sources of proteins.




Protein Shape Determines Function

• The final shape of a protein determines its function.

• Connective tissue proteins and collagen are elongated.

• Hemoglobin has a spherical shape.

• If the shape of a protein is altered, its function may be disrupted.




If Protein Shape is Altered, Function May Be Altered



DENATURATION OF PROTEINS

PROTEINS ARE ALWAYS COILED

UNDERGO UNCOILING; IRREVERSIBLE

THIS IS CALLED DENATURATION

FUNCTIONAL ABILITY CHANGES

EXAMPLE- EGG PROTEIN



DENATURATION

• CAUSES HEAT EXPOSURE TO

ACID

• EFFECTS PROTEIN’S 3-D

STRUCTURE ALTERED

BROKEN DOWN INTO POLYPEPTIDES

PREPARATION FOR DIGESTION




Proteins that May Harm Certain Individuals: Phenylketonuria

• PKU is an inherited condition attributed to a defective gene.

• Aspartame, a sugar substitute, contains phenylalanine.

Tyrosine is considered a conditionally essential amino acid

Food Proteins and Health



Protein and Health: Deficiency

Marasmus From the Greek ‘to waste away’ Lack of calories and protein

• Starvation Sufferers weigh only HALF as

much as normal

Kwashiorkor Caused by an acute lack of

protein Bloated look associated with

starvation Wasted muscles

Marasmus Kwashiorkor

http://cnhs.gmu.edu/hsci530nurs534/04-MacronutrientMalnutrition.doc



Protein and Health: Excess

The problems of protein excess can be found in developed countries Possible to overload the liver and kidneys;

potential risk of kidney stones Can promote calcium excretion Excess protein can be converted to energy

and stored as body fat No apparent benefit to consuming too much

protein when caloric intake is adequate



Allergies

• Food allergens = proteins that are not broken down by the digestive tract which then cross the GI lining to enter the blood stream

• 8 foods cause 90% of all allergic reactions egg fish milk peanuts shellfish soy tree nuts wheat

http://www.foodallergy.org/index.html

The immune system is involved



• Additional Slides




Amino Acids



Soy

Heart Health ClaimClaim requirement (need to say on label):

1. 25 grams of soy protein a day, as part of a diet low in saturated fat and cholesterol, may reduce the risk of heart disease. A serving of [name of food] supplies __ grams of soy protein OR

2. Diets low in saturated fat and cholesterol that include 25 grams of soy protein a day may reduce the risk of heart disease. One serving of [name of food] provides __ grams of soy protein



According to the US Food and Drug Administration:

Soy protein products can be good substitutes for animal products because, unlike some other beans, soy offers a 'complete' protein profile. ... Soy protein products can replace animal-based foods—which also have complete proteins but tend to contain more fat, especially saturated fat—without requiring major adjustments elsewhere in the diet. •Ref: Henkel, John (May–June 2000). "Soy:Health Claims for Soy Protein, Question About Other Components". FDA Consumer (Food and Drug Administration) 34 (3): 18–20.PMID 11521249

•Negative of soy consumption in large quantities is the hormonal effects.



Whey

• Milk Protein

• High in sulfur containing amino acids antioxidant anticarcinogen immune stimulating

• High concentrations of the branched chain amino acids - muscles

http://www.wheyoflife.org/faq.cfm#1



Reported Whey Benefits

• Cardiovascular benefits (antihypertensive and hypocholesteremic)

• Anticarcinogenic effects

• Antibacterial and antiviral properties

• Antioxidant actions

• Immune system stimulation

• Improved bone formation/reduced bone loss

• Increased mineral absorption

• Reduction of tooth enamel demineralization and plaque formation

• Appetite suppression

• Rebuilding of muscle tissue



Protein & Athletes, Sports

• Intake of dietary protein 1.2 - 1.6 grams of protein per kilogram of body weight can almost always be obtained in the normal diet

• Special mixtures of amino acids stimulating muscle growth NO solid evidence

• Amino acids and CHO metabolism No hard evidence that this occurs or has bearing on sport

performance

BOTTOM LINE: Exercise hard, eat right (a varied diet), rest

http://www.gssiweb.com/reflib/refs/258/rt42.cfm?pid=38



Function of Food Proteins

1. Water Binding

gelatin, non-fat dry milk solids

2. Browning- non enzymatic

Maillard - chemical reaction

3. Structure

gluten for bread, egg white meringue

4. Sweetening

aspartame

5. Fat Substitute

microsized egg protein



Protein Functions in Foods

Beverages………………………….. Viscosity

Soups, sauces……………………... Viscosity, emulsification

Dough, baked goods……….……… Matrix, gelation, browning

Dairy…………………………………. Fat retention, Emulsification

Egg substitutes……………………… Foaming, Gelation

Meat products………………………. Absorption, Cohesion

Food coating…………….…………… Cohesion

Confectionary…………..……………. Dispersibility, emulsification

proteins enzymes, hormones, and body building lecture 4 february 2, 2015 dr. ponnusamy

Documents

protein protein

energy slide

proteins macronutrient

word protein

protein deficiency

protein matrix

sources of protein

sufficient protein