Biochemistry - Proteins and enzymes Flashcards
What are proteins?
Naturally occurring condensation polymers consisting of chains of amino acids.
Types of protein structure?
primary
secondary
tertiary
quaternary
What’s the primary structure?
Sequence of amino acids.
What allows amino acids to be in a sequence?
Amino acids joined by peptide bonds/links forms between carboxyl group of one amino acid and one amine group of another.
How is the primary structure depicted?
Depicted by three letter notation arranged in an appropriate sequence.
Process for determining the sequence of amino acids in a protein?
- Sequence of amino in a protein is determined experimentally.
- Amino acid reacted with a substance that creates a coloured or fluorescent derivative.
- Protein is then hydrolysed by a highly specific enzyme that removes only the terminal enzyme.
- Marked amino acid is identified by chromatography.
- Repeating processes many times determines the full primary structure.
What’s the secondary structure?
Chain of amino acids that makes up the primary structure can fold itself in two ways.
What’s the secondary structure dependant on?
Depends on the sequence of amino acids that are next to each other.
Hydrogen bonds hold the folded structures in place.
How does the primary structure become the secondary structure?
It folds into either Alpha helixes or Beta plated sheets.
What’s the tertiary structure?
Folding of chain held by interactions between more distinct amino acids.
How is the tertiary structure maintained?
Hydrogen bonds, disulphide bridges, ionic bonds and intermolecular forces.
What’s the quaternary structure?
Structure resulting from interaction between separate protein chains.
True or false? All proteins have a quaternary structure.
False, most do.
Example of quaternary structure?
Haemoglobin - 4 protein channels - 2 alpha chains and two beta chains.
Two types of proteins?
Fibrous and globular.
Features of fibrous proteins?
- Long molecules
- Strengthened by many cross links between chains.
Examples of structures fibrous proteins form?
Muscle fibres.
Features and example of globular proteins?
- Smaller more round and compact.
- E.g Ferretin - primary store of iron inside cells in animals and plants.
Example of role of globular proteins?
Enzymes and certain hormones.
What sort of thing can disrupt a proteins structure? And how?
High temperature - Exposing proteins to high temp denatures them.
What are enzymes and what do they do?
Biological catalysts.
They increase the rate of biochemical reactions
Without them reactions would be so slow life wouldn’t happen.
What do enzymes do? And how?
- Enzymes speed up a reaction by providing an alternative route of lower activation energy.
- Do this by binding the reactant molecule, and holding it in a favorable orientation for reaction.
Basic process of enzyme reaction.
Enzyme + substrate > enzyme/substrate complex > Enzyme + product.
As a catalyst what happens to the enzyme?
Enzyme is released unchanged at end of the reaction.
