PROTEINS
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PROTEINS. The Science of Food . What are Proteins?. Amino Acids Essential amino acids Complimentary proteins Specific chemical properties (charge, hydrophic, hydrophilic) Amino acid chemistries give proteins their primary, secondary, tertiary structure

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PROTEINS

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Proteins

PROTEINS

The Science of Food


What are proteins

What are Proteins?

  • Amino Acids

    • Essential amino acids

    • Complimentary proteins

    • Specific chemical properties (charge, hydrophic, hydrophilic)

  • Amino acid chemistries give proteins their primary, secondary, tertiary structure

  • Structure function relationships

  • Biological roles of proteins


Organization of information from genetics to protein

Organization of Information- From Genetics to Protein

1.Proteins are made of amino acids.

2. The amino acids are chemically different and can occur in any order. (ate, eat, tea)

3. The amino acids chemically interact with each other to give the protein its shape and function.


Essential amino acids

Essential Amino acids

  • There are eight amino acids that cannot be produced by the human body.

  • Histidine, Isoleucine, Leucine, Lysine, Phenyl-alanine, lysine, methionine, threonine, Valine

  • Complete proteins contain all the essential amino acids.

  • Incomplete proteins lack one or more

  • Complimentary proteins make up for each other’s deficiency.

  • Beans lack methionine. Corn lacks lysine.

  • Other complimentary proteins:

    Soybean & sesame, Rice and black-eyed peas

  • There are eight amino acids that cannot be produced by the human body

  • Histidine, Isoleucine, Leucine, Lysine, Phenyl-alanine, lysine, methionine, threonine, Valine

  • Complete proteins contain all the essential amino acids

  • Incomplete proteins lack one or more

  • Complimentary proteins make up for each other’s deficiency

  • Beans lack methionine, Corn lacks lysine

  • Other complimentary proteins:

  • Soybean & sesame, Rice and black-eyed peas


Peptide bonds and primary structure

Peptide bonds and Primary Structure


Protein measurement measure of amino ends

Protein measurement- measure # of amino ends.

Protein adulteration- add melamine, many amino ends.


Secondary structure

Secondary structure

Alpha helix

Beta Pleated Sheet


Tertiary structure

Tertiary structure

  • The overall conformation that arises from the secondary structure


Proteins

  • Show chain demonstration

  • Do protein denaturation demonstration

  • Start attendance sheets


Proteins

Conventional Wisdom,The “Central Dogma of Biology”DNA makes RNA makes (only one) Protein.Corollary: Only DNA can transmit information.(Proteins store that information.)


Stanley b pusiner

Stanley B. Pusiner


Puisner discovers prions

Puisner discovers prions!

Human TSEs include Creuzfeldt-Jacob disease (CJD),

Familial fatal insomnia (FFI), Kuru,

and Gerstmann-Straussler-Scheinker disease (GSS).

Animal TSEs(aka “Mad Cow”)


Stanley b pusiner 1997 nobel prize

Stanley B. Pusiner, 1997 Nobel Prize


Biological functions of proteins

Biological Functions of Proteins

  • Catalysis - enzymes

  • Movement –actin, myosin, trypomysin

  • Antigens

  • Antibodies

  • Toxins

  • Structure –collagen,

  • Keratin

  • Transfer – Iron, O2


Actin and myosin

Actin and Myosin

The muscles in your body are made of the proteins actin and myosin.

The use a combination of Ca2+ and ATP to contract and release.

The muscles in a body will under go rigor mortis once there is no energy going through them. (Tenderization)


Functions of proteins in foods

Functions of Proteins in Foods

  • Precipitation – loss of solubility (milk, casein, para-kapppa casein – denaturation)

  • Flocculation –aggregation without denaturation, clarification

  • Coagulation – internal self association

  • Gelatinization- ordered self association


Functions of proteins in foods1

Functions of Proteins in Foods

  • Emulisfication

  • Dough formation

  • Color and flavor formation

  • Water binding, foaming, viscosity


Proteins and nutrition 4 cal gram protein quality protein efficiency ratio

Proteins and Nutrition 4 Cal/gramProtein Quality = Protein Efficiency Ratio

P.E.R = weight gain in rat per gram of protein

Meat: 10-20 pounds feed 1 pound beef

Poultry: 1.5 pound feed  1 pound poultry

Meat has 15-20% protein, 5-40% fat, rest water


Proteins

Meat: 10-20 pounds feed 1 pound beef

Poultry: 1.5 pound feed  1 pound poultry

Meat has 15-20% protein,

5-40% fat,

remainder is water


Protein requirements

Protein Requirements

Athletes need more. 4:1 carb:protein


Enzymes

Enzymes

  • Make reactions go faster

  • Have no side products

  • Are highly specific

  • Natural – no one has ever chemically synthesized an enzyme

  • Work at relatively low temperatures

  • “Gentle”


Enzymes in foods

Enzymes in Foods


Enzymatic reactions in foods

Enzymatic Reactions in Foods

  • Lipases break down triglycerides to mono and diglycerides

  • Polyphenol oxidase causes the natural browning of foods


Summary of proteins

Summary of Proteins

  • The information in genes is translated into a specific sequence of amino acids.

  • The information in the amino acid sequence determines the protein’s secondary, tertiary, sequence and ultimately functions.

  • Diverse functions of proteins

    nutrition

    movement

    functions in food

    enzymes


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