Electrochemical Detection in Biochemical Reactions
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Questions and Answers

What happens to the ECL signal when a stem-loop of the ECL probe is converted into a linear double-helix configuration in the presence of target ss-DNA?

  • Remains unchanged
  • Decreases (correct)
  • Increases
  • Fluctuates
  • Which enzyme is commonly used as a sensor biorecognition element for urea determination/monitoring in medical and environmental applications?

  • Glucose oxidase
  • Catalase
  • Glucose dehydrogenase
  • Urease (correct)
  • In the first transduction mechanism mentioned, what product is formed when glucose oxidase catalyzes the oxidation of glucose?

  • Glucose
  • Gluconolactone + H2O2 (correct)
  • NADH
  • Glucose dehydrogenase
  • What type of prosthetic group is utilized by glucose dehydrogenase in the second transduction mechanism for glucose biosensors?

    <p>NAD+</p> Signup and view all the answers

    Which enzyme is commonly used in glucose biosensors as the recognition element for catalyzing glucose oxidation?

    <p>Glucose dehydrogenase</p> Signup and view all the answers

    Which of the following measurable reaction products arise from the catalytic process involving catalytic enzyme-based sensor recognition elements?

    <p>Protons</p> Signup and view all the answers

    What is the substrate used in the biosensor for the enzyme alkaline phosphatase (ALP)?

    <p>PNPP</p> Signup and view all the answers

    Which type of receptor is responsible for the recognition in the biosensor?

    <p>Cell receptor</p> Signup and view all the answers

    What disrupts normal physiological function, leaving a detectable signature on the cells?

    <p>Pathogen</p> Signup and view all the answers

    In the biosensor system, what reduces a yellow water-soluble reaction product that absorbs light at 405 nm?

    <p>Enzyme ALP</p> Signup and view all the answers

    Which enzyme is used in the biosensor system for detection?

    <p>Alkaline phosphatase (ALP)</p> Signup and view all the answers

    Which type of biosensor uses an antigen-antibody reaction to effect a transducer signal change?

    <p>Immunosensor</p> Signup and view all the answers

    What serves as the electron sinks in the electrochemical detection approach of glucose biosensors?

    <p>Inorganic redox couples</p> Signup and view all the answers

    What does the quinoprotein glucose dehydrogenase use to oxidize alcohols and amines in the alternative transduction scheme?

    <p>PQQ</p> Signup and view all the answers

    What is the problem with immunosensors compared to enzyme-based sensors?

    <p>They only involve a binding reaction with the antigen</p> Signup and view all the answers

    Which component is essential for glucose oxidation in the reaction catalyzed by glucose dehydrogenase?

    <p>PQQ(ox)</p> Signup and view all the answers

    What are some examples of electrochemical mediators used in the detection approach of glucose biosensors?

    <p>Organic dyes like Prussian Blue</p> Signup and view all the answers

    Study Notes

    Electrochemical Detection

    • Glucose dehydrogenase is used in an electrochemical detection approach where the product (hydrogen peroxide or NADH) is detected by an electrochemical mediator.
    • Examples of electrochemical mediators include organic dyes (e.g. Prussian Blue) and inorganic redox couples that serve as electron sinks.

    Glucose Dehydrogenase Mechanisms

    • The 1st mechanism uses glucose dehydrogenase to oxidize glucose to gluconolactone with NAD+ as a cofactor, producing NADH and H+.
    • The 2nd mechanism uses glucose dehydrogenase with an orthoquinone cofactor (PQQ) to oxidize glucose to gluconolactone, producing PQQ(red).

    Recognition Receptors

    • Antibody-based recognition involves an antigen-antibody reaction to effect a transducer signal change.
    • Enzyme-based recognition uses catalytic enzymes, producing measurable products such as protons, electrons, light, and heat.
    • Examples of enzyme-based recognition elements include urease, glucose oxidase, and glucose dehydrogenase.

    Glucose Biosensors

    • Glucose biosensors use glucose oxidase to catalyze the oxidation of glucose to gluconolactone, producing H2O2.
    • The H2O2 is then detected electrochemically.
    • Alternative glucose biosensors use glucose dehydrogenase, producing NADH instead of H2O2.

    Cell Receptors on Biosensors

    • Cell receptors on biosensors use mammalian cells and alkaline phosphatase (ALP) to detect pathogens/toxins.
    • The ALP catalyzes the conversion of PNPP to a yellow, water-soluble product that absorbs light at 405 nm.
    • Pathogen-induced cellular damage produces a detectable signature of the pathogen.

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    Description

    Explore the dominant detection approach in biochemical reactions, which involves electrochemical detection of products like hydrogen peroxide or NADH using organic dyes or inorganic redox couples. Learn about the alternative transduction scheme involving quinoprotein glucose dehydrogenase.

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