J. C. Servaites, in Plant Physiol. (1985) 78:839–843, observed that Rubisco from tobacco leaves collected before dawn had a much lower specific activity than the enzyme collected at noon. This difference persisted despite extensive dialysis, gel filtration, or heat treatment. However, precipitation of the predawn enzyme by 50% (NH4)2SO4 restored the specific activity to the level of the noon-collected enzyme. Suggest an explanation.

J. C. Servaites, in Plant Physiol. (1985) 78:839–843, observed that Rubisco from tobacco leaves collected before dawn had a much lower specific activity than the enzyme collected at noon. This difference persisted despite extensive dialysis, gel filtration, or heat treatment. However, precipitation of the predawn enzyme by 50% (NH4)2SO4 restored the specific activity to the level of the noon-collected enzyme. Suggest an explanation.

Basic Clinical Laboratory Techniques 6E

6th Edition

ISBN:9781133893943

Author:ESTRIDGE

Publisher:ESTRIDGE

Chapter6: Basic Clinical Chemistry

Section6.5: Blood Glucose And Hemoglobin A1c

Problem 8RQ

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Based on the Lineweaver-Burke plot attached. Kinetic data were generated in the (1) absence of any inhibitor, (2) presence of 15 µM of a reversible inhibitor, or (3) presence of 20 µM of a second (distinct) reversible inhibitor. Purified enzyme concentration was 5 µM. The y-intercept of Lines (A) and (B) is 0.9 sec/uM; the y-intercept of Line (C) is 0.3 sec/uM. The slope of Line (A) is 1.8 sec; the slope of Lines (B) and (C) is 0.6 sec. Calculate the Km of the reaction represented by Line (B).
Based on the Lineweaver-Burke plot attached. Kinetic data were generated in the (1) absence of any inhibitor, (2) presence of 15 µM of a reversible inhibitor, or (3) presence of 20 µM of a second (distinct) reversible inhibitor. Purified enzyme concentration was 5 µM. The y-intercept of Lines (A) and (B) is 0.9 sec/uM; the y-intercept of Line (C) is 0.3 sec/uM. The slope of Line (A) is 1.8 sec; the slope of Lines (B) and (C) is 0.6 sec. Which of the following statements is true? Select any/all answers that apply. A. Both types of inhibitor mediate a slope effect on the Lineweaver-Burke plot. B. Both types of inhibitor decrease the apparent Vmax for this enzyme-catalyzed reaction. C. Both types of inhibitor alter the apparent Km of this enzyme-catalyzed reaction. D. Lines (A) and (C) share the same X-intercept, indicating that the noncompetitive inhibitor decreases the apparent Km of this enzyme-catalyzed reaction. E. Lines (A) and (C)…
Based on the Lineweaver-Burke plot attached. Kinetic data were generated in the (1) absence of any inhibitor, (2) presence of 15 µM of a reversible inhibitor, or (3) presence of 20 µM of a second (distinct) reversible inhibitor. Purified enzyme concentration was 5 µM. The y-intercept of Lines (A) and (B) is 0.9 sec/uM; the y-intercept of Line (C) is 0.3 sec/uM. The slope of Line (A) is 1.8 sec; the slope of Lines (B) and (C) is 0.6 sec. Calculate the catalytic efficiency of the reaction represented by Line (A).
Based on the Lineweaver-Burke plot attached. Kinetic data were generated in the (1) absence of any inhibitor, (2) presence of 15 µM of a reversible inhibitor, or (3) presence of 20 µM of a second (distinct) reversible inhibitor. Purified enzyme concentration was 5 µM. The y-intercept of Lines (A) and (B) is 0.9 sec/uM; the y-intercept of Line (C) is 0.3 sec/uM. The slope of Line (A) is 1.8 sec; the slope of Lines (B) and (C) is 0.6 sec. QUESTION: Line (A) represents ____________. A. an enzyme-catalyzed reaction in the absence of any inhibitor. B. an enzyme-catalyzed reaction in the presence of a competitive inhibitor. C. an enzyme-catalyzed reaction in the presence of an uncompetitive inhibitor. D. an enzyme-catalyzed reaction in the presence of a noncompetitive, or mixed, inhibitor.
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Enzymatic method does not require prior separation of individual sugars. True or False?
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To purify a given enzyme from a crude extract that contains it, fractional precipitations, exchange chromatography are successively tested ionic and exclusion chromatography, with the results shown in the following table: Volume of dissolution Protein concentration Enzymatic activity (ml) (mg/ml) (U/ml) a) Calculate the percentage of recovery of the enzyme after each of the manipulations to which it has been subjected. b) Indicate if it is necessary to continue purifying the enzyme or if it is expected to have reached its electrophoretic homogeneity.
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