Proteins

Protein Basics Made of C,H,O, N CHONPS Monomers = amino acids - 20 different types of amino acids used to make proteins The bonds between amino acids are called peptide bonds so… Proteins are polymers that are also called Polypeptides.

Meet the monomer –Amino acid 3 main parts - Amino group NH2 - Carboxyl group COOH - R group (side chain) each of the 20 types of amino acids have a unique R group

Proteins form from chains of amino acids Proteins vary in length – can be 1,000s of amino acids long Protein

Proteins Shape A protein’s shape is determined by the order that amino acids are joined in The shape of a protein determines its function Hemoglobin antibody enzymes polymerase

Protein Structure – Primary Structure Primary structure is the order of the amino acids that make up a protein. - the interactions of the R groups on each amino acid cause the molecule to bend and fold – different arrangements create different shapes - as a result- the order of amino acids determines the shape of the protein - shape determines function - changing a single amino acid can change a protein’s shape.

Enzymes: “Helper” Protein molecules

Chemical reactions of life Processes of life building molecules synthesis breaking down molecules digestion + +

Nothing works without enzymes! How important are enzymes? all chemical reactions in living organisms require enzymes to work building molecules synthesis enzymes breaking down molecules digestive enzymes enzymes speed up reactions “catalysts” enzyme + enzyme We can’t live without enzymes! +

Enzymes A protein catalyst Enzymes are important proteins found in living things. An enzyme is a protein that changes the rate of a chemical reaction. They speed up metabolic reactions.

Examples synthesis enzyme + digestion enzyme +

Enzymes are proteins Each enzyme is the specific helper to a specific reaction each enzyme needs to be the right shape for the job enzymes are named for the reaction they help sucrase breaks down sucrose proteases breakdown proteins lipases breakdown lipids DNA polymerase builds DNA Oh, I get it! They end in -ase

Enzymes aren’t used up Enzymes are not changed by the reaction used only temporarily re-used again for the same reaction with other molecules very little enzyme needed to help in many reactions substrate product active site enzyme

It’s shape that matters! Lock & Key model shape of protein allows enzyme & substrate to fit specific enzyme for each specific reaction

2 1 3

Enzyme vocabulary Enzyme Substrate Products Active site helper protein molecule Substrate molecule that enzymes work on Products what the enzyme helps produce from the reaction Active site part of enzyme that substrate molecule fits into

What affects enzyme action Correct protein structure correct order of amino acids why? enzyme has to be right shape Temperature pH (acids & bases)

Order of amino acids Wrong order = wrong shape = can’t do its job! DNA folded protein chain of amino acids DNA right shape! folded protein chain of amino acids DNA wrong shape!

Temperature Effect on rates of enzyme activity Optimum temperature greatest number of collisions between enzyme & substrate human enzymes 35°- 40°C (body temp = 37°C) Raise temperature (boiling) denature protein = unfold = lose shape Lower temperature T° molecules move slower fewer collisions between enzyme & substrate

Temperature 37° human enzymes reaction rate temperature What’s happening here?! 37° reaction rate temperature

pH Effect on rates of enzyme activity changes in pH changes protein shape~ Denatures most human enzymes = pH 6-8 depends on where in body pepsin (stomach) = pH 3 trypsin (small intestines) = pH 8

pH 1 2 3 4 5 6 7 8 9 10 11 12 13 14 stomach pepsin intestines trypsin What’s happening here?! reaction rate 1 2 3 4 5 6 7 8 9 10 11 12 13 14 pH

Two examples of Enzyme Inhibitors a. Competitive inhibitors: are chemicals that resemble an enzyme’s normal substrate and compete with it for the active site. Enzyme Substrate Competitive inhibitor

Inhibitors b. Noncompetitive inhibitors: Inhibitors that do not enter the active site, but bind to another part of the enzyme causing the enzyme to change its shape, which in turn alters the active site. Enzyme Noncompetitive Inhibitor Substrate active site altered

For enzymes… What matters? SHAPE!