Enzyme activity: A simple analogy

Abel, Kenton B.; Halenz, Donald R.

doi:10.1021/ed069p9

Cited by 6 publications

(6 citation statements)

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“…However, this introduces the difficulty of explaining why the steady-state current in the plateau at 0.5−0.65 V is about the same measured at higher potentials, above 0.86 V (at which electrooxidation of dissolved CO on a CO-free Pt surface takes place), and is in good agreement with the diffusion-limited current calculated assuming that all the Pt surface is electroactive . Obviously, electron tunneling through the CO-covered Pt surface cannot be invoked, due to the strongly poisoning character of chemisorbed CO, perhaps the first known electrocatalytic poison . The simplest explanation is that the CO-free Pt patches act as microelectrodes whose hemispherical diffusion layers grow until their overlap has the effect of simulating a completely active electrode surface…”

Section: Introductionmentioning

confidence: 76%

“…2 Obviously, electron tunneling through the CO-covered Pt surface cannot be invoked, due to the strongly poisoning character of chemisorbed CO, perhaps the first known electrocatalytic poison. 8 The simplest explanation is that the CO-free Pt patches act as microelectrodes whose hemispherical diffusion layers grow until their overlap has the effect of simulating a completely active electrode surface. 9 Although possibly no other electrocatalytic system is so simple as that of CO/Pt/HClO 4 aqueous solution, as far as we know no other system shows such a clear-cut influence of the admission potential of the substrate.…”

Section: Introductionmentioning

confidence: 99%

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Necessity of CO-Free Pt Sites for the Electrooxidation at Low Potentials of Dissolved CO on Polycrystalline Pt

et al. 1996

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We have studied the effect of several experimental variables (CO admission time, bubbling rate of CO, and magnetic stirring of the electrolyte) on the electrooxidation at low potentials of dissolved CO on Pt. Although this electrooxidation was affected by changes in the said variables, in all cases it was always accompanied by the presence in the same potential range of a hump of chemisorbed CO (here designated as CO (1)) in parallel CVs recorded in the absence of dissolved CO and whose charge was about 15% of a monolayer of chemisorbed CO. Since this hump of chemisorbed CO(1) preceded the main peak of electrooxidation of chemisorbed CO, it is clear that electrooxidation of the dissolved CO takes place only on this 15% of the Pt surface free from chemisorbed CO(1). The stationary currents, the peak currents, and the Cottrell plots of dissolved CO electrooxidation were in good agreement with those calculated for a wholly active surface. The only possible explanation of this behavior is that the CO(1)-free Pt sites act as an ensemble of microelectrodes, so that the overlap of their hemispherical diffusion layers yields the same current density as a conventional electrode. Actually, both plots of peak potential vs the logarithm of the sweep rate and of peak current density vs the square root of the sweep rate yielded the linear behavior expected of conventional electrodes, which shows that the time necessary for both electrooxidation of the chemisorbed CO(1) and for the said overlap was negligible for sweep rates up to 10 V s -1 . From this an upper value of about 3 µm for the diameter of the CO-free patches was estimated.

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Section: Introductionmentioning

confidence: 76%

Section: Introductionmentioning

confidence: 99%

Necessity of CO-Free Pt Sites for the Electrooxidation at Low Potentials of Dissolved CO on Polycrystalline Pt

et al. 1996

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“…Other analogies were surprisingly developed and complex in terms of the features of enzyme kinetics addressed. Abel and Halenz presented a seemingly innocuous analogy, in which enzyme catalysis was represented by a child (“the enzyme”) and a balloon (“the substrate”), where the catalytic event involved the child popping a balloon. Building on this idea, it was discussed that increasing the number of balloons influences rate, up to a limit (i.e., reaching V max ), and the role of optimal temperature for enzyme functionality was addressedthe child would not be able to pop balloons as well if the temperature was too high or too low.…”

Section: Enzyme Kinetics Analogiesmentioning

confidence: 99%

“…In this paper we provide an overview of analogies published in the education literature, focusing on analogies used to describe enzyme kinetics. The interest in enzyme kinetics analogies stemmed from work by the authors that investigated how students reason about enzyme kinetics, in which it was noted there was a lack of research on the teaching and learning of enzyme kinetics, , but there was a rich body of resources for practitioners, including a variety of analogies that can be used to explain enzyme kinetics. − Most of these analogies and analogy-based activities were published in this Journal , due to the variety of manuscript types available for publication (e.g., articles, commentaries, activities, etc.). After presenting an overview of the different analogies and the aspects of enzyme kinetics addressed in each analogy, an analogy for enzyme kinetics is presented by the authors that (1) incorporates evidence-based practices related to analogies (informed by the work of Orgill and colleagues) − and (2) specifically addresses an aspect of enzyme kinetics determined to be challenging for students based on our recent research related to enzyme inhibition …”

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confidence: 99%

Catalyzing Student Learning: Using Analogies To Teach Enzyme Kinetics

Rodriguez

Towns

2019

J. Chem. Educ.

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Analogies are useful tools instructors can use to help make challenging concepts less abstract by drawing connections to familiar contexts. In this paper we provide an overview of the various analogies published in the education literature that are situated in the context of enzyme kinetics, including narrative-based analogies (analogies intended to be presented by an instructor in a lecture setting) and activity-based analogies (analogies that serve as the basis for interactive tasks intended to be completed by students in a laboratory/small group setting). After discussing the published analogies, we present an analogy we developed that incorporates previous research regarding the effective use and presentation of analogies in biochemistry. Our analogy focuses on supporting students in distinguishing between the different types of enzyme inhibitors, which has been previously determined to be challenging for students.

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“…Today’s educational standards at elementary and high school levels focus mostly on teaching the central dogma of biology (DNA → RNA → proteins), while much of the educational research at these levels focuses on enzyme kinetics. − Here we present proteins as essential materials in medical applications. Enzymes are proteins (and sometimes RNA molecules) that catalyze biological reactions; therefore, they accelerate chemical reactions occurring in living systems.…”

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confidence: 99%

Show Yourself, Asparaginase: An Enzymatic Reaction Explained through a Hands-On Interactive Activity

et al. 2017

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Determining the catalytic activity of an enzyme can be the perfect method for its identification, for example during purification procedures or for isolation purposes. Herein, we used a pharmaceutically relevant protein to bring the concept of enzymatic activity to the classroom. We designed a hands-on interactive activity in which a medically relevant enzyme, asparaginase, was distinguished from a nonenzymatic protein based on its specific enzymatic activity. The experiment was carried out in the classroom, designed to impact different educational levels from elementary to high school. Our main purposes were to promote the emerging field of protein-based drugs as a source of scientific careers in bionanotechnology and to show the students an image of a “scientist” as that of a common and educated person working in an exciting profession. In addition of being inexpensive, this activity proved to be adaptable for various educational levels and can be easily implemented in different scenarios, for example, scientific fairs, some schools, and so forth.

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Enzyme activity: A simple analogy

Abstract: Presented here is a simple analogy that has helped students in our classes grasp the concept of enzyme activity

Cited by 6 publications

References 0 publications

Necessity of CO-Free Pt Sites for the Electrooxidation at Low Potentials of Dissolved CO on Polycrystalline Pt

Necessity of CO-Free Pt Sites for the Electrooxidation at Low Potentials of Dissolved CO on Polycrystalline Pt

Catalyzing Student Learning: Using Analogies To Teach Enzyme Kinetics

Show Yourself, Asparaginase: An Enzymatic Reaction Explained through a Hands-On Interactive Activity

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