Enzyme Science Miscellaneous


Direction: A Nick Translation reaction in a final volume of 100µl was carried out by using 25 µCi of labeled [α-32P]–dCTP for labeling a 1.2 Kb λ-Interferon DNA fragment.

  1. After completion of Nick translation reaction, 10 µl of reaction was spotted on a glass-fiber filter that upon counting resulted into 4.2 × 104 cpm in reaction. Another 10 µl was processed for TCA precipitation to determine redioisotope incorporation. The TCA precipitated sample gave 2.94 × 104 cpm. What is the percent of [α-32P]-dCTP incorporation into the DNA sample?









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    % incorporation is calculated by incorporation into precipitated form. (The polymerized form will precipitate).

    =
    Precipitate from epm
    total epm

    =
    2.94 × 104 emp
    × 100 ≅ 70%
    4.2 × 104 emp

    Correct Option: D

    % incorporation is calculated by incorporation into precipitated form. (The polymerized form will precipitate).

    =
    Precipitate from epm
    total epm

    =
    2.94 × 104 emp
    × 100 ≅ 70%
    4.2 × 104 emp


Direction: An enzyme (24000 Da) undergoes first-order deactivation kinetics while catalyzing a reaction according to Michaelis-Menten kinetics (Km= 10–4 M). The enzyme has a turnover number if 104 molecules substrate/min-(molecule enzyme) and a deactivation constant (kd) of 0.1 min–1 at the reaction conditions. The reaction mixture initially contains 0.6 mg/l of active enzyme and 0.02 M of the substrate.

  1. The maximum possible conversion for the enzymatic reaction will be











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    NA

    Correct Option: E

    NA



  1. The time required to convert 10% of the substrate will be rapproximately











  1. View Hint View Answer Discuss in Forum

    NA

    Correct Option: E

    NA


  1. In a chemostat, evaluate the dilution rate at the cell wash-out condition by applying Monod’smodel with the given set of data: µmax = 1h–1;Yx/s = 0.5 g g–1; Ks = 0.2 g L–1; S0 = 10 g L–1









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    We know, from Monod's equation
    μ = μmax [S0/(KS + S0)]
    ⇒ μ = 1 * [10/(0.2 +10)] = 10/10.2 = 0.98
    At wash out, Dilution rate D = μ
    Therefore,
    the required dilution rate = 0.98 hr–1

    Correct Option: C

    We know, from Monod's equation
    μ = μmax [S0/(KS + S0)]
    ⇒ μ = 1 * [10/(0.2 +10)] = 10/10.2 = 0.98
    At wash out, Dilution rate D = μ
    Therefore,
    the required dilution rate = 0.98 hr–1



  1. Evaluate the Michaelis constant for the following lipase catalyzed trans-esterification reaction for the production of biodiesel

    where, k1 = 3 × 108 M–1 s–1; k = 4 × 10³ s–1 and k2 = 2 × 10³ s–1









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    Km =
    K1 + K2
    K1

    =
    4 × 104S-1 + 2 × 108 S-1
    3 × 108M-1S-1

    =
    4200
    3 × 108

    = 1.4 × 10-4M

    Correct Option: D

    Km =
    K1 + K2
    K1

    =
    4 × 104S-1 + 2 × 108 S-1
    3 × 108M-1S-1

    =
    4200
    3 × 108

    = 1.4 × 10-4M