DID YOU MISS THE TEST BEFORE THE BREAK?

DID YOU MISS THE TEST BEFORE THE BREAK? Today is the last day to make it up in tutorial.

Open to yesterday’s entry- Entry 11. Proteins: Amino Acids in 3 D- 2/27/12Let’s review what we talked about yesterday.

2 Types of Proteins1) Structural – proteins that form physical parts.

Examples – -keratin (hair and nails)-actin (muscle)-microtubules (cell membrane

skeletons) - gelatin

- collagen

2) Functional – Proteins that have activityExamples--Hormones – used for signaling-Defensive – antibodies that recognize foreign

invaders-Transport – Carrier proteins!!!-Enzymes – used for chemical reaction- Hemoglobin – found on RBC and carry oxygen

Protein Shape Determines Function

Example – Fibrous proteins are long and thin, and are used for structure

What will we learn today?

HOW is the shape of a protein determined.

Proteins are made ofchains of amino acids

What are amino acids?

Link to amino acid 3-D models

H2NAminogroup C

Side chain

R

H

C

O

OH

Carboxylgroup

Non-ionized form

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

CCO

O–

H

H3N+

H

Glycine (G)Gly

C CO

O–

H

H3N+

CH3

Alanine (A)Ala

C CO

O–

H

H3N+

CHH3C CH3

Valine (V)Val

C CO

O–

H

H3N+

CH2

H3C CH3

Leucine (L)Leu

CH

CCO

O–

H

H3N+

CH

Isoleucine (I)Ile

CH3

CH2

H3C

Side chains contain carbon and/or hydrogen

CO

O–C

CH2

CH2

H2C

H2N+

H

Proline (P)Pro

Each amino acid has a different side chain.

CH3N+

CH2

H

C

O

O–

Phenylalanine (F)Phe

CH3N+

CH2

H

C

O

O–

Tyrosine (Y)Tyr

OH

CH3N+

CH2

H

C

O

O–

NH

Tryptophan (W)Trp

Side chains contain ring structures

Each amino acid has a different side chain.

CH3

CH2

CH2

S

C CH3N+

HO

O–

Methionine (M)Met

SH

CH2

C CH3N+

HO

O–

Cysteine (C)Cys

Side chains contain sulfur

Each amino acid has a different side chain.

OH

CH2

C CH3N+

HO

O–

Serine (S)Ser

Threonine (T)Thr

CH

C CH3N+

HO

O–

CH3HO

Side chains contain hydroxyl functional groups

Each amino acid has a different side chain.

C

CH2

C CH3N+

HO

O–

H2N O

Asparagine (N)Asn

CH2

C CH3N+

HO

O–

CH2

C

OH2N

Glutamine (Q)Gln

Side chains contain amino functional groups

Each amino acid has a different side chain.

CH2

C CH3N+

HO

O–

NH

+NH

Histidine (H)His

CH2

C CH3N+

HO

O–

CH2

CH2

+NH3

CH2

Lysine (K)Lys

Basic side chains

CH2

C CH3N+

HO

O–

CH2

CH2

NH

C +NH2

NH2

Arginine (R)Arg

Each amino acid has a different side chain.

CH2

C CH3N+

HO

O–

C

O– O

Aspartate (D)Asp

Acidic side chains

CH2

C CH3N+

HO

O–

CH2

C

O– O

Glutamate (E)Glu

Each amino acid has a different side chain.

H

H H H H H HO O O H H O H H O

N C C N NC C C C

H CH3 CH2

OH

N-terminus

N C C

CH2

C

O

OH

CH2

N C C

CH

CH3H3C

CH2

OH

H H O

N C C

H H O

N C C

H H O

N C C

CH2

SH

OH

C-terminus

H2N

H

H

C CO

OHCarboxylgroup

H2N

H

CH3

C CO

OHAminogroup

H2N

H

H

C

O

C N CC

HH

CH3

OH

O

Peptidebond

+ H2O

H2N Gly Ala Ser Asp

N-terminus

21 3 54 6 7 8

Phe Val Tyr Cys

C-terminus

COOH

+

Proteins are chains of amino acids

Protein Model activityPeptides are chains of amino acids and

sometimes used as another word for protein. Get four amino acids per table (group of two)

Follow the instructions of your teacher to build peptides using the paper amino acid models for questions #1-4.

Then join your chain with another groups chain to form an 8 amino acid chain for #5

Amino Acid sequence determines the 3-D protein shape

• Interactions between amino acids cause folding and bending of the chainExamples: – positive (+) and negative (-) parts of amino

acids are attracted to each other.– hydrophobic regions are attracted to each

other– Sulfur is attracted to each otherMUST be an amino acid between them to attach by paper clips

COMPLETE #6-7

CH2 OH CH2C

O

N

H

HHydrogen bond between

two side chains

CH2 OH O C

OC H N

CH2CH

CH3

CH3

Hydrogen bond betweenside chain and peptide group

Hydrogen bond between peptide

groupsH3C

H3C

CHCH2

Hydrophobicinteraction

CH2 CH2S S

Disulfide bond

Ionic bond

(CH2)4 NH3+ –O

O

CCCH2

Figure 3.11a

Interactions that determine the structure of proteins

#8:

CYS- LEU- ARG- GLY- GLY-GLY- ASP- LEU- CYSS S

+ -

hydrophobic

hydrophobic

9. HOW WOULD YOU BE ABLE TO BUILD A COMPLETELY DIFFERENT PROTEIN USING THE SAME 8 AMINO ACIDS?• You could change the order (sequence of the

amino acids) which makes it a different shape (different protein).

• From yesterday: The shape of a protein determines its function.

• Now we know….The shape is determined by the sequence/order of amino acids and their interactions with each other.

Make an entry- Entry 12: Lactose Intolerance- 2/28/12See attached entryRead the information and answer questions on the worksheet.It will be homework if you don’t finish it.