Enzymes and Proteins Flashcards
Module 1
What is the general structure of an amino acid
Amino group, carboxylic acid group and R group
How many different amino acids are there
20
How are two amino acids bonded together and what molecule does this produce
By peptide bonds, produces a dipeptide
condensation reaction
How long is a peptide chain
Any length
What is the primary structure of a protein
Polypeptide chain held together by peptide bonds
What is the secondary structure of a protein
Areas of initial folding
- Alpha Helices or Beta pleated sheets
held together by hydrogen bonds
What is the tertiary structure in proteins
Interactions of R group
3D shape
4 types of bond:
- Hydrogen bonds
- Ionic Bonds
- Disulphide bridge
- Hydrophobic interactions
What are Disulphide bridges
Cysteine contains sulphur, when 2 cysteines are close, double covalent bonds form
V. strong
What is the Quaternary structure of an enzyme
2+ polypeptides join together
Or there is a prosthetic group
What is a conjugated protein
A globular protein with a prosthetic group
What happens to Fibrous and globular proteins when they denature
Fibrous - lose structural strength
Globular - insoluble and inactive
What are Fibrous proteins
Long rope like fibres with high tensile strength and are generally insoluble in water
eg:
- collagen, Keratin, Elastin
What does Collagen do?
Main component of connective tissue like ligaments, tendons, cartilage
What does keratin do
main component of hard structures like hair, nails, claws, feathers and hooves
What does Elastin do
Major protein component of tissues that require elasticity like arteries, lungs, skin, etc.
What are globular proteins
They have a spherical shape caused by tightly folded polypeptide chains, hydrophobic groups in, hydrophilic out - makes it soluble in water
- transport proteins, enzymes, hormones
What are the features of Haemoglobin
globular protein, 4 polypeptide chain subunit *2 alpha, 2 beta)
4 haem/prosthetic groups contain Fe2+ within 4 subunits
Conjugated protein
Soluble
Feature of amylase
Globular protein
Soluble
single chain of amino acids
secondary has alpha helices and beta pleated sheets
only works if a co-factor Cl- is bound to it
Insulin properties
Globular protein
soluble
two amino acids joined by disulphide bonds
What happens when an enzyme is placed in the wrong pH
active site denatures because the different number of H+ ions cause reaction which alter the tertiary structure of the enzyme. This means the substrate is no longer complimentary to the active site of the enzymes
What are the different types of inhibitors
Competitive
Non competitive
Permanent
What are competitive inhibitors
Similar shape to substrate, occupy active site temporarily to form enzyme-inhibitor complex
substrate cannot fit so no reaction is catalysed
What are non competitive inhibitors?
Attach to allosteric site, distorts 3D tertiary structure which changes enzymes active site. Substrate can no longer fit into active site
What are permanent inhibitors
Irreversible as it denatures enzyme
