3.1.4 proteins Flashcards
How does an enzyme increase the rate of reaction?
Lowers the activation energy
What does the properties of an enzyme relate to?
The tertiary structure of its active site and its ability to combine with complimentary substrates to form an enzyme/substrate complex.
What is the specificity of enzymes?
Specific enzymes catalyse specific reactions
What is the affect of enzyme concentration on enzymatic reactions?
- As the concentration of enzymes increase the rate of reaction will increase, until enzyme concentration and substrate concentration become equal, then the reaction plateaus as
- the substrate is the limiting factor
What is the affect of substrate concentration on enzymatic reactions?
- As the substrate concentration increase so will the rate of reaction until it becomes equal with the enzyme concentration and rate plateaus
- Enzyme concentration is the limiting factor
What is the affect of non-competitive inhibitor concentration on enzymatic reactions?
- inhibitor binds to a site on the enzyme away from the active site, causing the active sites tertiary structure to change shape, therefore it is harder for successful enzyme substrate complexes to form.
- Rate will increase as concentration of enzyme concentration increases, but slower than if there wasn’t an inhibitor, rate will never reach its full maximum
What is the affect of competitive inhibitor concentration on enzymatic reactions?
- the inhibitor has a similar structure to the substrate so also is able to bind with the enzymes active site
- The rate of reaction increase as enzyme concentration increases it will be faster than with a non-competitive inhibitor but slower than without an inhibitor
- The rate will eventually reach its maximum
What is the affect of pH on enzymatic reactions?
- if too high or low enzyme denatures due to the breaking of hydrogen and ionic bonds
- therefore active site is no longer a complimentary 3-D structure, so no enzyme/complexes are formed
What is the affect of temperature on enzymatic reactions?
- at low temperature, less kinetic energy in enzymes and substrates so less successful collisions. Often not enough activation energy.
- at high temperatures enzyme denatures by the breaking of hydrogen ionic and disulphide bonds, so active site is no longer a complimentary 3-D structure
What are amino acids?
The monomers that make up proteins
What is the general structure of an amino acid?
On the left: NH3- amine group
On the right: COOH- carboxylic acid
On the bottom: hydrogen
On the top: R group, this differs for different amino acids
How is a peptide bond formed?
- Condensation reaction between two amino acids
How are polypeptides formed?
- The condensation reaction of many amino acids
What is the primary structure of a protein?
- The specif order of the amino acids in the polypeptide chain, this is coded by ribosomes
What is the secondary structure of a protein?
- The folding of the chain
- This is controlled by hydrogen bonds between the H of the amine group and O of the carboxyllic acid
- Folded in two ways: a-helix or B-plated sheet
What is the tertiary structure of a protein?
- Bonds are formed between the R groups of amino acids
- ionic, hydrogen, polar/polar, non-polar/non-polar, disulphide
What is the quartinary strucure of a protein? With an example.
- Not all proteins have
- The bonding of 2 or more polypeptide chains
- Can have inorganic ions attached
- Haemoglobin is a protein with a quartinary structure, made up of two a-helix and 2 B-plated sheet, with four iron ions attached
What are some functions of proteins in organisms?
- enzymes
- transport - haemoglobin
- cell recognition - antigens
- channels - membrane proteins
- protection - antibodies
- hormones - insulin
What is the test for the presence of proteins?
- Bieuret
- lilac for a positive result
What are two ways of identifying different amino acids?
- Two chromotography:
Turning the paper 90 degrees and retesting to obtain a more accurate Rf value - Electrophesis:
Placing the solution in a circuit, it separates based on charge
