Enzyme Science Miscellaneous
- The turnover numbers for the enzymes, E1 and E2 are 150 s–1 and 15 s–1 respectively. This means
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Turnover number is expressed in molecules of product/active site/second. It can be defined as the number of molecules of a substrate acted upon in a period of 1 minute by a single enzyme molecule; with the enzyme working at a maximum rate.here the statement shows the dP/dt of the two enzymes at unit time. Again dP/dt is the velocity of the reaction i.e. the E1 has greater velocity than of E2.
Correct Option: B
Turnover number is expressed in molecules of product/active site/second. It can be defined as the number of molecules of a substrate acted upon in a period of 1 minute by a single enzyme molecule; with the enzyme working at a maximum rate.here the statement shows the dP/dt of the two enzymes at unit time. Again dP/dt is the velocity of the reaction i.e. the E1 has greater velocity than of E2.
- The dissociation constant Kd for ligand binding to the receptor is 10–7 M. The concentration of ligand required for occupying 10% of receptors is
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Given,
Dissociation constant, Kd = 10–7M
The reaction is: L + R → LR
Thus, Kd for the reaction = [L][R]/[LR]
or [LR]/[LR][R] = 10/100
Therefore, [L] = 1/9 * 10–7M = 10–8MCorrect Option: C
Given,
Dissociation constant, Kd = 10–7M
The reaction is: L + R → LR
Thus, Kd for the reaction = [L][R]/[LR]
or [LR]/[LR][R] = 10/100
Therefore, [L] = 1/9 * 10–7M = 10–8M
- Receptor R is over expressed in CHO cells and analysed for expression. 6 × 107 cells were incubated with its radioactive ligand (specific activity 100 counts per picomole). If the total counts present in cell pellet was 1000 cpm, the average number of receptors R per cell is (assume complete saturation of receptors with ligand and one ligand binds to one receptor)
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Number of ligands = total radioactivity/radioactivity in each ligand
= 1000 cpm/ 100 cpm/pmole
= 10 pmole
= 10 * 10–12 * 6.023 *10–12 * 6.023 * 1023 ligands
Thus, total ligands= 6.023 * 1012
Average number of receptors, R per cell = total receptor/number of cells
= 6.023 * 1012/6 * 107
= 105Correct Option: B
Number of ligands = total radioactivity/radioactivity in each ligand
= 1000 cpm/ 100 cpm/pmole
= 10 pmole
= 10 * 10–12 * 6.023 *10–12 * 6.023 * 1023 ligands
Thus, total ligands= 6.023 * 1012
Average number of receptors, R per cell = total receptor/number of cells
= 6.023 * 1012/6 * 107
= 105
- One unit of glucoamylase enzyme activity is defined as the amount of enzyme required to produce (imol of glucose per min in a 4% solution of Lintner starch at pH 4.5 and 60°C. If in a reaction mixture with 1ml of the crude enzyme preparation containing 8 mg protein and 9 ml of 4.44% starch, 0.6 µmc of glucose/ml-min is produced, what will be the specific activity of the crude enzyme preparation?
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NA
Correct Option: E
NA
- Which of the following techniques is best suited for immobilizing an affinity ligand?
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Affinity chromatography utilizes the specific interactions between two molecules for the purification of a target molecule. A ligand having affinity for a target molecule is covalently attached to an insoluble support and functions as bait for capturing the target from complex solutions. The affinity ligand can be any molecule that will bind the target without also binding other molecules in the solution.
Correct Option: D
Affinity chromatography utilizes the specific interactions between two molecules for the purification of a target molecule. A ligand having affinity for a target molecule is covalently attached to an insoluble support and functions as bait for capturing the target from complex solutions. The affinity ligand can be any molecule that will bind the target without also binding other molecules in the solution.
