8590995
Description
Flashcards by Katie Flaherty, updated more than 1 year ago
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Created by Katie Flaherty
over 7 years ago
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| Question | Answer |
| Initial Velocity definition? | The velocity of the reaction at the beginning of your experiment |
| KM definition? | the substrate conc. at which the initial velocity is half max velocity |
| Vmax definition? | the maximum velocity or rate at which the enzyme catalysed a reaction. (when all enzyme active sites are saturated with substrate) |
| How to work out Initial Velocity, KM and Vmax? |
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| Enzyme-substrate complex equation? |
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| Assumptions of that equation^? |
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| Michaelis-Menton equation? |
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| 6 classes of enzyme? | Oxidoreductases Transferases Hydrolases Lyases Isomerases Ligases |
| Oxidoreductase, type of reaction and example? |
-adds O2 or removes 2H
-lactate dehydrogenase (converts pyruvate to L-lactate)
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| Transferase, type of reaction and example? |
-transfer of functional groups
-alanine amino transferase (involved in glutamate to alanine equilibrium to take up alanine in the diet)
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| Hydrolase, type of reaction and example? |
-Hydrolytic reaction
-Trypsin, cleaves amino acid bonds by the addition of water (its active site it comp to peptide bonds)
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| Lyases, type of reaction and example? |
-add groups to C=C bonds
-ATP-citrate lyase (involved in reaction in the krebs cycle)
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| Isomerase, type of reaction and example? |
-isomerisation reactions
-phosphoglucose isomerase (involved in glycolysis step)
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| Ligase, type of reaction and example? |
-form C-C or C-N bonds with ATP cleavage
-DNA ligase (use ATP to catalyse the formation of new covalent bonds)
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| Cofactor and which cofactors are needed for cytochrome oxidase? | -a substance whose presence is essential for the activity of an enzyme (often inorganic) -Cu2+ and Fe2+/3+ |
| Coenzymes? | organic molecules that are required by certain enzymes to carry out catalysis |
| Isoenzymes? | - enzymes with different protein structures which catalyse the same reaction -They are coded for by different genes - Different isoenzymes are often found in different cellular compartments or different amounts in different tissues - They have distinct biochemical roles |
| Rearrangement of the Michaelis-Menton equation... | produces a straight line equation forming the Lineweaver-Burke plot |
| Four categories of enzymes? | Competetive- reversible competitive-irreversible non-competitive-reversible non-competitive-irreversible |
| Reversible inhibition definition? | inhibition of enzyme activity in which the inhibiting molecular entity can associate and dissociate from the protein's binding site. |
| Irreversible inhibition definition? | Irreversible inhibitors usually react with the enzyme and change it chemically (e.g. via covalent bond formation). |
| Effect of competitive inhibitors on enzyme activity? |
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| Effect of non-competitive inhibitor on enzyme activity? |
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| 2 clinical uses of enzymes inhibitors? | 1. Control of angiotensin production for treatment of heart failure - enzymes cleave the bonds or add more AA's at the sites to change the protein 2. Hydrolysis of ACh to increase levels and decrease effects of Alzheimer's |
| 3 Metabolic regulations of enzyme activity? | 1. Allosteric binding sites (+ or - effectors) 2. Covalent modification by other enzymes -phosphorylation (kinases) or dephosphorylation (phosphatases) 3. Induction/repression of enzyme synthesis |
| Homotropic and Heterotropic Allosteric Enzymes? | Homotropic - is a substrate for its target enzyme, as well as a regulatory molecule of the enzymes activity Heterotropic - is a regulatory molecule that is not the enzymes substrate – it may either be an activator or an inhibitor for the enzyme. E.g. H+ & CO2 are heterotropic allosteric modulators of haemoglobin |
| Example of Negative allosteric effectors? | ATP and citrate on Phosphofructokinase |
| Example of Positive allosteric effectors? | Phosphoenolpyruvate (PEP) and fructose 1,6 bisphosphate on pyruvate kinase |
| Effect of Allosteric enzymes on Conc./Velocity graph? |
Km is not applicable to non-MichaelasM enzymes so K0.5 is used instead
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| Covalent Modification effect on Glycogen synthesis or degradation? | -involves addition or removal or phosphate from Ser, Thr, Tyr or His residues - Phosphorylation of glycogen phosphorylase increases its activity so glycogen degrades - Phosphorylation of glycogen synthase decreases its activity and causes synthesis of glycogen -phosphorylation by protein kinase and dephos. by protein phosphatase |
| Adenylylation? | now known as AMPylation, is a process in which adenosine monophosphate (AMP) molecule is covalently attached to a protein side chain, altering the function of the protein. |
| 2 ways to regulate the amount of enzyme? | -high glucose levels leads to increase in insulin production which increases the rate of synthesis of key enzymes for gluc. metabolism -some enzymes are synthesised as larger inactive precursor forms called proenzymes or zymogens. Activation involves the irreversible hydrolysis of one or more peptide bonds- activating it. |
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