(n) structure and function of globular proteins including conjugated protein

How do globular proteins form

When proteins fol into their tertiary structure

What are 2 properties of globular proteins

Water soluble

Roughly spherical

What makes globular proteins soluble?

Hydrophobic R groups on amino acids are kept away from aqueous environments

Hydrophilic R groups are on the outside

Which makes it soluble

What Is an example of globular proteins

Insulin

What is insulin

A hormone involved in regulating blood glucose levels

What is the importance of insulin being a globular protein

It needs to be transported in the blood so it needs to be soluble

Needs to have a specific shape to fit into specific receptors in the cell surface membrane

What dos insulin consist of?

Consists of 2 polypeptide chains held together by 3 disulphide bridges

What is a conjugated protein

A globular protein that contain a prosthetic group

What are examples of prosthetic group? (4)

Lipids + Protein = lipoprotein

Carbohydrates + protein = glycoprotein

Metal ions

Molecules from vitamins

What type of protein is haemoglobin

Quarternary

What is the basic structure fo haemoglobnn

4 polypeptides

2 alpha subunits

2 beta subunits

Each unit has a prosthetic haem group

Why is ach subunit wrapped around a haem important

To prevent the oxygen from oxidising

Prevents damage by oxygen that it is transporting

What type of ion does haemoglobin and why is it important

Has Fe²+ ions that bind reversibly with an oxygen molecule

It’s how it enables oxygen to move around the body

How are the hydrophobic groups and hydrophilic groups facing?

Hydrophobic groups are facing inwards (helps preserve 3-D shape)

Hydrophilic R groups - facing outwards -(maintains solubility)

Why is the arrangement of R groups important?

Important to the function of haemoglobin

If changes occur to sequence of a.a - properties changing

For example

Sickle cell anaemia - non polar molecules replace more polar molecules = less soluble

Give an example of enzyme of globular proteins

Catalase

What typ of enzyme is catalase

Intrazellulär enzyme

What type of protein is catalase

Quartnerary

What does catalase enzymes include

Contains 4 haem prosthetic group

Fe²+ ions allow catalase to interact with hydrogen peroxide and speed up its breakdown

What is the by product of catalase reactions?

Hydrogen peroxide

Damages the cell if accumulates

So catalase converts hydrogen peroxide into water and oxygen preventing damage