Regulation of Enzymes (4.2) Flashcards
State 3 factors that regulate enzymatic activity
- temp
- pH
- enzyme and substrate concentration
Describe temperature as a factor regulating enzymatic activity
Enzyme-catalysed reactions will generally increase as the temperature increases.
Describe the effect of cold temperatures on enzymatic activity
When enzymes fall below the optimal temperature, the rate of the reactions will slow down. Collision rate will also decrease and conformational changes will not occur.
Describe the optimal temperature range of human enzymes
36-38C
Describe the homeostatic temperature of humans
37C
State the optimal temperature of Taq polymerase
70C
Describe pH as a factor regulating enzymatic activity
If enzymes are taken too far above or below their optimal pH range, then the tertiary structure is affected and the substrate may not be able to bind.
Describe the effect of high temperatures on enzymatic activity
The hydrogen bonds and hydrophobic interactions of tertiary and quaternary structures are broken and enzyme shape will change so that the substrate cannot bind. The reaction won’t occur.
Describe the effect of non-ideal pH on enzymatic activity
If the reaction occurs in an environment in which the pH is not ideal, the micro-environment of the active site may provide a different pH to create a specific environment.
Describe the effect of enzyme and substrate concentration on enzymatic activity
The concentration of enzymes compared to substrates affects the rate of reactions.
Describe the effect of high enzyme concentration on reaction rate
High enzyme concentration compared to substrate will mean the reaction occurs over a short period of time
Describe the effect of low enzyme concentration on reaction rate
Low enzyme concentration compared to substrate will mean the reaction occurs over a long period of time
State 3 factors that determine if enzymes are able to catalyse reactions
- inhibition
- phosphorylation
- cofactors and coenzymes
State the 2 characteristics of enzyme inhibition
- reversible
2. irreversible
Describe reversible inhibition
Bonds formed between the inhibitor and enzymes are weak, so they are easily broken and inhibition reversed.
Describe irreversible inhibition
Bonds formed between the inhibitor and enzymes are strong, so the binding is irreversible.
Describe the effect of reversible inhibition on enzyme activity
Inhibitor can move in and out of the active site, which reduces the activity of the enzyme because its active site will not be available for the substrate to bind to as often.
Describe the effect of irreversible inhibition on enzyme activity
Inhibitor blocks all enzyme activity permanently and the enzyme will not be able to partake in reactions.
Describe the 3 major types of inhibition
- competitive
- non-competitive
- feedback
Describe competitive inhibition
Shape of the inhibitor is similar to substrate shape. As a result, inhibitors bind to enzyme active site and block the substrate.
Describe non-competitive inhibition
Allosteric inhibiton
Describe the allosteric site
Site on enzyme other than the active site to which an effector molecule binds
Describe the 2 possible consequences of allosteric regulation
- allosteric inhibition
- allosteric activation
Describe allosteric inhibition
Inhibitor binds to an allosteric site which changes enzyme shape and prevents the substrate from binding.
Describe allosteric activation
Some molecules that bind to allosteric sites can cause a conformational change that allows reactions to occur.
Describe feedback inhibition
Product produced late in a pathway inhibits enzyme activity earlier in the pathway.
Provide a step by step description of feedback inhibition and its’ effect on enzyme activity
- amount of inhibitors increase
- inhibitors bind to enzymes
- reduces amount of inhibitors
- less inhibitors bind to enzymes
- enzyme functions again
Describe the effect of phosphorylation and dephosphorylation on enzyme activity
Phosphorylation and dehosphorylation can change protein structure
Describe phosphorylation
Process of adding a phosphate group to a molecule
Describe dephosphorylation
Reaction that involves the removal of a covalenty coupled phosphate group from another molecule.
Describe the effect of cofactors on enzyme activity
Some enzymes require additional components that enable them to catalyse reactions.
Describe the effect of coenzymes on enzyme activity
For certain enzymes, specific coenzymes are required to catalyse reactions
Provide 3 examples of cofactors
- iron
- magnesium
- ATP
Provide 3 examples of coenzymes
- ATP
- NADPH
- NADH
State whether or not coenzymes are often structurally altered during reaction and whether or not they revert to their original form at reaction completion
Yes. Coenzymes are often structurally altered and revert to their original form once the reaction has been completed
Describe what coenzymes ATP, NADH, NADPH, FADH2 act as
Metabolic intermediates
Describe the role of metabolic intermediates
Carry chemical groups between different reactions
Describe the role of metabolic intermediates in maintaining cellular processes
Store and transport chemical groups, protons and electrons from one reaction to another
Describe the unloaded form of a coenzyme
Form of a coenzyme that is free to accept a proton, electron or chemical group
Describe the loaded form of a coenzyme
Form of a coenzyme that has a proton, electron or chemical group to donate
Describe what the cycling between loaded and unloaded coenzymatic forms is referred to as
Cycling of a coenzyme
Describe chemical group
Group of covalently linked atoms
Describe the role of ATP and ADP during reactions
Involved in energy transfer
Describe what the breakdown of ATP to ADP results in
The release of energy stored in the bond between the third phosphate and ADP molecule
Describe the role of NAD+/NADH
Involved in electron transfer
Describe coenzyme
Organic molecule that combines with an enzyme and supports activity
Describe cofactor
Chemical component that is required for the proper function of proteins
Describe saturation point
Maximum rate of reaction where increasing the enzyme or substrate concentration further does not affect the reaction rate.
Describe an oxidation reaction
Occurs when a coenzyme donates an electron
Describe a reduction reaction
Occurs when a coenzyme accepts electrons
Describe how coenzymes are involved in oxidation and reduction reactions
Coenzymes are involved in the transfer of electrons between reaction or biochemical pathways
State whether or not AUG is the starting amino acids for all functional proteins.
No. There are some rare exceptions
e.g. Fungus Candida albicans
State whether or not introns or extrons are spliced out during RNA processing
Introns are spliced. Exons are expressed as proteins or RNA and form mRNA strand.
