Protiens And Enzymes Flashcards
(21 cards)
Structure of an amino acid
Properties of r groups
Hydrophobic
Hydrophilic
Positively charged
Negatively charged
Describe how a peptide bond is formed between 2 amino acids?
Condensation reaction between amine of one amino acids and carboxyl group of another amino acid by loss of a water molecule forming a peptide bond
Primary structure
Number and sequence of amino acids in a polypeptide chain joined by peptide bond by condensation reaction
Secondary structure
Folding of the polypeptide chain into alpha helix or beta pleated sheets joins by many weak hydrogen bonds which provide strength and stability
Tertiary structure
Further folding of the polypeptide chain to form a specific 3D complex with hydrogen, disulphide and ionic bonds between R groups of different amino acids
Quaternary structure
2 or more polypeptide chains joined together
What are enzymes
They are globular protiens which act as globular catalysts. A catalyst increases the rate of reaction by providing an alternative pathway or lowering activation energy but don’t get used up. They do this by distorting bonds in the substrate
What is activation energy
Minimum amount of energy required for a reaction to occur
Do proteins have binding or active sites?
They have binding sites
Don’t get mixed up
Lock and key model
Active site is rigid and doesn’t change shape
Enzyme has an active site specially perfectly complementary to the substrate
Forms enzyme substrate complexes by lowering activation energy
Induced fit model
Active site is not complementary to the substrate
Active site bind to the substrate but slightly changing its tertiary structure abd inducing itself around the substrate by stress and distort of bonds reducing activation energy
Enzyme substrate complexes
Factors affecting enzyme action
Temperature
PH
Substrate/ enzyme concentration
Effect of Temperature
As temperature increases , the kinetic energy increases as more successful collisions are more and and substrate complexes form
At the optimum temperature , the maximum number of enzyme substrate complexes are are being formed per second
Past the optimum temperature many weak hydrogens bonds break as to much vibration which changes the tertiary structure of the enzyme which means its no longer specifically complementary to the substrate so no enzyme substrate complexes form
Effect of PH
As PH moves away from the optimum the hydrogen and ionic bonds are altered which changes the shape of the active site such means no longer specifically complementary to the substrate and no enzyme substrate complexes formed
Factors affecting enzyme action
Temperature
PH
Substrate/ enzyme concentration
Inhibitors
Why is a buffer added?
To maintain a constant PH as it will denature the protein
Effect of substrate/ enzyme concentration
As a substrate Concentration increases the rate of reaction also increases as the number of enzymes substrate complex is formed per second increases. Rate of reaction also increases. Eventually, the graph plateaus as the as the enzyme concentration becomes a limiting factor. All the enzyme active sites are fully occupied ( same idea with enzyme concentration as not enough active sites)
Graph for competitive and Mon competitive inhibitor
Explain how a competitive inhibitor works?
Has a similar shape to the substrate and temporarily binds to the active site
Fewer enzyme substrate complexes formed as active site is blocked
Can be overcome by increasing substrate concentration
Explain how a non competitive infinity works?
Inhibitor binds to the alosteric site away from the active site which causes a permanent change to the tertiary structure so no longer specifically complementary and no enzyme substrate complexes formed
Cannot be overcome
