Daily Starter

Explain how a peptide bond is formed. (What is the reaction called and how does it happen?)

TAKE OUT YOUR AMINO ACID CHART

Protein Structure• The structure of a

protein is very complex, with many twists and folds.

• Proteins are folded into a 3-dimensional structure and held together by chemical bonds.

4 Levels of Protein Structure

PrimarySecondaryTertiaryQuaternary

Primary Structure(1st Level)

The linkage of amino acids in a specific order.

This connection is made by dehydration condensation and called a peptide bond.

Primary Structure(1st Level)

The linkage of amino acids in a specific order.

This connection is made by dehydration condensation and called a peptide bond.

Disulfide Bridges Some primary structures include disulfide bridges

These are formed when 2 cysteine amino acid molecules lost their H (hydrogen) and covalently bond together

DiSulfide Bridge (Primary structure)

Secondary Structure(2nd Level)

The polypeptide chain (chain of a.a.) will begin to form H-bonds with adjacent a.a. molecules

H-bonds are somewhat weak so they will form, break, and reform as the protein continues to twist and take a shape.

Secondary Structure(2nd Level)

Many H-bonds are needed to hold together a secondary structure (the more, the stronger the hold)

There are 2 kinds of secondary folding patterns:

1. Alpha Helix2. Beta pleated

sheets

Secondary Structure(2nd Level)

Many H-bonds are needed to hold together a secondary structure (the more, the stronger the hold)

There are 2 kinds of secondary folding patterns:

1. Alpha Helix2. Beta

pleated sheets

Alpha HelixThe slightly negative Oxygen from the carboxyl (COO-) forms a H-bond with the slightly positive Hydrogen from the amino group (NH3+)

Beta Pleated SheetThe slightly negative Oxygen from the carboxyl (COO-) forms a H-bond with the slightly positive Hydrogen from the amino group (NH3+)

Video on Protein Folding

http://youtu.be/lijQ3a8yUYQ

http://youtu.be/yZ2aY5lxEGE