Lecture 3-Proteins

Primary structure

Amino acid sequence

Secondary structure

Local regions for structures like alpha helix or beta sheets

Tertiary structure

Final 3-d structure of the protein

Quaternary structure

Multiple proteins coming together

Secondary structures:

Alpha helix and beta sheets for by hydrogen bonds

The alpha helix and beta sheets are formed by hydrogen bonds, where does the hydrogen come from

The hydrogen on the nitrogen involved in the peptide bond with the oxygen from the carbonyl

Properties of the alpha helix

Hydrophobic because the side chains all point outward and they are all hydrophobic

Side chains in a beta sheet

Alternate direction, with one row pointing in and then the next row pointing out

Helix breaking amino acid

Proline

Multiple secondary structures come together to form the ____

Tertiary structure

What happens when 2 helixes come together

They wrap together to keep their hydrophobic side chains on the inside and minimize the contact with aqueous environment; like a ZIPPER

proteins that have a mechanical or structural role

Collagen

Elastin

Collagen

Triple helix which give structure to skin and bone

Antibodies

Proteins which bind to antigens and the clump together to make a star

Helps immune system

Enzyme catalysts

Lower activation energy to make a reaction happen

How do enzymes speed up reactions

Stabilizing (lowering energy) of transition state of the reaction

How can enzymes catalyze using orientation

It can bind to the substrate and position them in such a way that encourages a reaction between the two

How can enzyme catalyze using partial charges

Sometimes the binding of the enzyme to the substrate causes the electrons to rearrange and form delta (-) and (+) charges that favor a reaction

How can enzymes catalyze using positional strain

The enzyme binds to the substrate and orients it in a way so that the substrate structure is stressed and forcing it towards a transition state to start the reaction

Active site

The part of the enzyme that binds to the substrate