1 What makes an enzyme specific to one

What will we learn today? HOW is the shape of a protein determined? WHY

Proteins are made of chains of amino acids What are amino acids? Link to

There are 20 different amino acids. All have the same general form. H Amino

Each amino acid has a different side chain. H H 3 N+ C C

Each amino acid has a different side chain. H H 3 N+ C CH

Each amino acid has a different side chain. H H 3 N+ C H

Each amino acid has a different side chain. H H 3 N+ H O

Proteins are chains of amino acids H H 2 N H O + C

Amino Acid sequence determines the 3 -D protein shape • Interactions between amino acids

Figure 3. 11 a Interactions that determine the structure of proteins H N C

Figure 3. 11 b Tertiary structures are diverse. A tertiary structure composed mostly of

Paper polypeptides activity Peptides are chains of amino acids and sometimes used as another

Explain the connection between the order of the amino acids and the shape of

Essential amino acids and nutrition • Consider why protein is needed and what amino

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1. What makes an enzyme specific to one type of reaction (in other words, what determines the function of a protein)? – SHAPE determines the function of a protein and makes enzymes specific to one reaction 2. How does heating (boiling) affect the ability of an enzyme to perform its function? – Heating/boiling denatures enzymes (unfolds them) and makes them lose their function

What will we learn today? HOW is the shape of a protein determined? WHY does heating/boiling denature enzymes and make them lose their function? Also: • What makes hair straight or curly and how do perms work? • Why is it important to eat different types of food to supply our protein needs?

Proteins are made of chains of amino acids What are amino acids? Link to amino acid 3 -D models

There are 20 different amino acids. All have the same general form. H Amino group H 2 N C R O C Carboxyl group OH Side chain Non-ionized form

Each amino acid has a different side chain. H H 3 N+ C C H H O O Glycine (G) Gly – H 3 N+ H O C C CH 3 O Alanine (A) Ala – O C C – CH O H 3 C CH 3 H 3 N+ Valine (V) Val H O C C – CH 2 O CH H 3 C CH 3 H 3 N+ Leucine (L) Leu Isoleucine (I) Ile H 3 N+ H O C C – O O H 3 C CH H 2 C CH 2 H 2 N+ CH 3 Proline (P) Pro These side chains contain only carbon and/or hydrogen

Each amino acid has a different side chain. H H 3 N+ C CH 2 H O H 3 N+ C O– C H O H 3 N+ C CH 2 O– CH 2 NH OH Phenylalanine (F) Phe Tyrosine (Y) Tyr Side chains contain ring structures Tryptophan (W) Trp

Each amino acid has a different side chain. H H 3 N+ C CH 2 H O H 3 N+ C O– CH 2 C O C CH 2 SH S CH 3 Methionine (M) Met Side chains contain sulfur Cysteine (C) Cys O–

Each amino acid has a different side chain. H H 3 N+ C H O H 3 N+ C CH 2 OH Serine (S) Ser O– CH HO CH 3 Threonine (T) Thr Side chains contain hydroxyl [OH] functional groups

Each amino acid has a different side chain. H H 3 N+ H O C H 3 N+ C CH 2 O– C C CH 2 C H 2 N O CH 2 O C H 2 N Asparagine (N) Asn O Glutamine (Q) Gln Side chains contain amino [NH 2] functional groups O–

Each amino acid has a different side chain. H H 3 N+ H O C H 3 N+ C O– CH 2 NH +NH H O C H 3 N+ C CH 2 O– C CH 2 NH 3 C O– CH 2 +NH O C +NH 2 Histidine (H) His Lysine (K) Lys Basic side chains Arginine (R) Arg

Each amino acid has a different side chain. H H 3 N+ H O C H 3 N+ C CH 2 C O– – C CH 2 C O O CH 2 O C O– Aspartate (D) Asp O Glutamate (E) Glu Acidic side chains O–

Proteins are chains of amino acids H H 2 N H O + C C H OH Carboxyl group H 2 N Amino group C O H 2 N C CH 3 OH H O H H C C N C H Peptide bond O C + OH CH 3 C-terminus N-terminus H H 2 O H H O H H O N C C N C C CH 3 H CH 2 OH C CH 2 CH H 3 C OH CH 2 CH 3 OH CH 2 SH O OH N-terminus H 2 N C-terminus Gly Ala Ser Asp Phe Val Tyr Cys 1 2 3 4 5 6 7 8 COOH

Amino Acid sequence determines the 3 -D protein shape • Interactions between amino acids cause folding and bending of the chain Examples: – positive (+) and negative (-) parts of amino acids are attracted to each other. – hydrophobic regions are attracted to each other • Folding http: //www. stolaf. edu/people/giannini/flashanimat/proteins/hydrophobic%20 force. swf • Structure levels http: //www. stolaf. edu/people/giannini/flashanimat/proteins/protein structure. swf

Figure 3. 11 a Interactions that determine the structure of proteins H N C O Hydrogen bond between peptide groups CH 2 OH O C Hydrogen bond between side chain and peptide group H CH 2 OH CH 3 O H 3 C CH 2 CH (CH 2)4 CHCH 2 CH 3 H 3 C NH 3+ Ionic bond Hydrophobic interaction O N CH 2 C H Hydrogen bond between two side chains –O CH 2 S S CH 2 Disulfide bond CCCH 2

Figure 3. 11 b Tertiary structures are diverse. A tertiary structure composed mostly of a-helices A tertiary structure composed mostly of b-pleated sheets A tertiary structure rich in disulfide bonds

Paper polypeptides activity Peptides are chains of amino acids and sometimes used as another word for protein. Follow the instructions of your teacher to build peptides using the paper amino acid models.

Straight, curly, and “permed” hair

Explain the connection between the order of the amino acids and the shape of the protein. Why did the boiled lactase not work any more? (base your answer on the paper model)

ESSENTIAL AMINO ACIDS

Essential amino acids and nutrition • Consider why protein is needed and what amino acids and proteins are used for in the body. Describe the symptoms you would expect a person with protein deficiency to have. • Look at Table 1. Which amino acids does corn lack (not have)? Which amino acids do beans and legumes lack (not have)? • Vegans are vegetarians that do not eat any food from animals, including milk and eggs. Why must vegans combine foods from a variety of plant sources to avoid protein deficiency (for example rice and beans instead of only beans)? • A new protein supplement for athletes and weightlifters advertises that it is the best because it is made of “ 100% natural organic corn protein”. Why would this not be a good product for athletes and weightlifters?