Metabolism 1-2 Flashcards
What is chirality?
A geometric property where the molecule is non-superimposable, with four different groups attached to the central atom (chiral centre), giving rise to enantiomers.
What form are proteins found in nature and why?
L-form as they are thought to have increased stability.
How are proteins held together?
Covalent bonds and disulphide bridges (oxidised cysteine side chains)
How are beta-pleated sheets formed?
Hydrogen bonds arise between the N-H and C=O groups.
What is another name for ionic interactions?
Salt bridges
How do Van der Waals forces compensate for their weak strength?
Strong in numbers
How do proteins structure themselves?
Fold into the conformation of lowest energy, occurring spontaneously or involve chaperones (which ensure that the folding occurs along the most energetically-favourable pathway).
What is the basic structure of an amino acid?
- Central C atom
- R group (different in each AA)
- COOH group (carboxylic acid group)
- NH2 group (amine)
What is the secondary structure of a protein?
The local structural changes within a protein that is determined by the AA sequence.
e.g. alpha helices and beta-pleated sheets
What is the tertiary structure of a protein?
The arrangement of the secondary structure in compact globular structures called domains.
e.g. active sites
What is the quartenary structure of a protein?
3D structure of a multimeric protein composed of several subunits.
e.g. oxyhaemoglobin is composed of 4 subunits
Why are coupled reactions used?
Reactions that synthesise molecules are generally energetically unfavourable so they are often coupled with an energetically favourable reaction to allow them to occur (often the hydrolysis of ATP is used).
What is a transition state?
The conformation of a substrate in which the atoms are rearranged both geometrically and electronically so that reaction can proceed. Enzymes bend their substrates so that are bonds and broken and they resemble the transition state.
What is the induced fit model?
The theory that a substrate induces a conformational change in the protein, resulting in the formation of an active site. Upon release of the products, the enzyme reverts back to its original shape.
What does lysozyme do?
Causes the hydrolysis of sugar molecules within bacterial cell walls. Found in tears and nasal secretions. Cause bacteria to lyse and die.
