By DCBy DC

H2O

How much of you is protein?

Amino Acids: “Dry” form

Carboxylic acid

Amino group

Radical group

Ionization? What’s it do in water?

H+

H+

“wet” form

Amino Acids: (cont)

•20 various radical groups•some nonpolarnonpolar•some polar or chargedpolar or charged

Condensation or Dehydration Synthesis

Peptide bond

Dipeptide

Synthesis of a dipeptidedipeptide:

Protein Structure:•The final shape of a protein determines its

function

•Proteins are either globular or fibrous

Levels of Protein Structure:

•There are four possible levels of folding

1) Primary (10)

2) Secondary (20)

3) Tertiary (30)

4) Quaternary (40)

Folding

• Nothing more than the amino acid sequence

• What forces hold it in this structure?

ex? Lysozyme

Pro-Insulin- a globular protein

Primary structure

Insulin- the finished hormone

Folding

• Actual folding • Radicals not involved (yet)

• Forces responsible? Hydrogen Bonds

• Two possibilities

Helix & Pleats

Helix (first type found)

Pleats (the second found)

Folding

• Results in final shape

• Actual folding

• Result of radical group interactions

• Four types of forces

Folding

• Bonding of two different polypeptides

• Covalently bonded

Denaturation of Proteins

• Destruction of its“native” configuration

• Environmental cause?

• 3-D shape is fragile

• temperature & pH changes

SupportKeratin

Support

Collagen

Enzymes

Catalase

Active site

2H2O2

O2

2H2O

Transport

Hemoglobin

Transport

Channel Proteins

Transport

Microtubules

CommunicationHormones

Communication

Receptor Proteins

Defense

Antibodies

Motion

Muscle fibers

Actin

Myosin