MSOP1016 Drug-Receptor Interactions & Isosteres Lecture Quiz
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Questions and Answers

Which term refers to chemical substances that interact with a biological system to produce a physiological effect?

  • Bioisosteres (correct)
  • Transition state isosteres
  • Receptor antagonists
  • Isosteres
  • What is the key principle of lead optimization in medicinal chemistry?

  • Selecting random functional groups
  • Focusing solely on pharmacokinetics
  • Optimizing target interaction (correct)
  • Avoiding any changes to the chemical structure
  • In drug-receptor interactions, what do bioisosteres mainly focus on?

  • Decreasing drug efficacy
  • Increasing drug toxicity
  • Modifying functional groups while retaining biological activity (correct)
  • Enhancing drug solubility
  • Which type of isosteres mimic the transition state of a reaction rather than the substrate or product?

    <p>Transition state isosteres</p> Signup and view all the answers

    What is the primary goal of using isosterism and bioisosterism in medicinal chemistry?

    <p>To enhance the selectivity of drugs</p> Signup and view all the answers

    Which text would be useful for referring to an overview presentation on relevant pages regarding medicinal chemistry?

    <p>'Medicinal Chemistry: An Introduction' by Thomas, G.</p> Signup and view all the answers

    What factor affects the affinity of a drug to its receptor by influencing the stereochemical fit and shape complementarity?

    <p>Intermolecular interaction forces</p> Signup and view all the answers

    Which term refers to the strength of binding of a single molecule to its ligand, typically measured by the equilibrium dissociation constant (KD)?

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

    What type of compounds produce a biological response by having affinity to their target but not activating the receptor?

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

    Which chemical properties are involved in controlling the Drug-Receptor Interaction through non-covalent interactions?

    <p>Ion-dipole interactions and Charge-transfer complexes</p> Signup and view all the answers

    Which term refers to the dissociation constant used to evaluate and rank the strengths of bimolecular interactions?

    <p>Equilibrium constant (Kd)</p> Signup and view all the answers

    Why do optical isomers act differently in biological systems?

    <p>Because of their stereochemical fit with receptors</p> Signup and view all the answers

    What type of interaction do anticholinesterase agents have with enzymes at the active site?

    <p>Covalent bonding</p> Signup and view all the answers

    Which process does Parathion undergo to inhibit acetylcholinesterase irreversibly?

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

    What is the active metabolite of Parathion that is used for the treatment of glaucoma?

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

    What is the key principle in lead optimization when optimizing target interactions?

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

    In drug-receptor interaction, what is used to optimize access to the target in Prodrugs and drug optimization?

    <p>Transition state isosteres</p> Signup and view all the answers

    Which type of agents interact non-selectively with all enzymes containing serine at the active site?

    <p>Acylating agents</p> Signup and view all the answers

    Which type of bioisosterism involves the use of a double bond to position essential functional groups into a particular spatial arrangement?

    <p>Non-classical Bioisosterism</p> Signup and view all the answers

    In classical bioisosterism, replacement of OH by an amino group leads to the formation of which antimetabolite?

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

    Which group is often used as a bioisostere for an amide in drug design?

    <p>Pyrrole ring</p> Signup and view all the answers

    What type of isosteres are utilized to design transition state analogues for enzyme inhibitors?

    <p>Transition state (TS) isosteres</p> Signup and view all the answers

    Which atom or group is commonly substituted by fluorine due to similar van der Waals radii and electronegativity?

    <p>-OH</p> Signup and view all the answers

    What steric factor is considered less important when a sulfonamide group replaces a phenol hydroxy in catecholamines?

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

    Which type of covalent bonding leads to irreversible binding between a drug and a receptor?

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

    In the context of bioisosteres, what does 'N C P + + As+' refer to?

    <p>Trivalent isosteres</p> Signup and view all the answers

    What term describes the replacement of functional groups with other groups having similar properties?

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

    What is the concept of isosterism applied to in drug design?

    <p>Functional groups</p> Signup and view all the answers

    What law accounts for similarities in groups having the same number of valence electrons?

    <p>Grimm's Law</p> Signup and view all the answers

    Which of the following is NOT considered a classical bioisostere according to the text?

    <p>Different electron distribution</p> Signup and view all the answers

    What is a challenge mentioned in relation to relating physico-chemical properties to biological activity?

    <p>Difficulty in simultaneous interpretation</p> Signup and view all the answers

    Which functional group can be ionized at physiological pH, imposing a positive charge on the molecule?

    <p>-NH2 (Amine)</p> Signup and view all the answers

    In isosterism, what does the concept of ring equivalents refer to?

    <p>Exchangeable groups in aromatic ring systems</p> Signup and view all the answers

    'Bioisosteres' are defined as groups with near equal shapes, volumes, and electron distribution that exhibit similar what?

    <p>'Biological activity'</p> Signup and view all the answers

    'Chemical isosterism' was developed to describe similarities in physical properties based on what characteristic?

    <p>'Valence electrons'</p> Signup and view all the answers

    What term describes replacing -CH=CH- in benzene with -S- or -O-?

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

    Study Notes

    Absorption, Distribution, Metabolism, Excretion (ADME)

    • Pharmacokinetics and pharmacodynamics are crucial in drug development • Lead discovery and optimization involve structure-activity relationships, binding interactions, and pharmacophores

    Functional Group Modification: Isosterism

    • Isosteric replacement: replacing functional groups with similar physical and chemical properties • Coined by Langmuir (1919) to describe similarities in physical properties (e.g., atoms with the same number of valence electrons) • Grimm's Hydride Replacement Law (1925) accounts for similarities in groups having the same number of valence electrons

    Bioisosteres

    • Groups or molecules with similar physico-chemical properties (shape, volume, electron distribution) having similar biological activity • Difficult to relate physico-chemical properties to biological activity, as many properties are involved simultaneously • Classical bioisosteres obey original conditions of Langmuir and Grimm • Non-classical bioisosteres do not obey steric and electronic definitions of classical bioisosteres

    The Drug-Receptor Interaction

    • A drug is a chemical substance that interacts with a biological system to produce a physiological effect • Drug-receptor interaction involves physical and chemical characteristics of drugs (e.g., solubility, surface activity, partition coefficient) • Target or receptor: a cellular macromolecule that a drug binds to initiate its effects (e.g., protein, nucleic acid, lipid, carbohydrate)

    Factors Controlling the Drug-Receptor Interaction

    • Steric factors (stereochemical fit; complementarity of shape) • Non-covalent interactions (electrostatic effects, hydrogen bonding, hydrophobic interactions, van der Waals or London Dispersion forces) • ADME processes (pharmacodynamics and pharmacokinetics)

    Covalent Bonding and the Drug-Receptor Interaction

    • Formation of a covalent bond between a drug and a receptor leads to irreversible binding (irreversible inhibitor) • High reactivity can lead to high toxicity, used only for prolonged effects (bactericides, anticancer, pesticides)

    Transition State Isosteres

    • A special type of isostere used to design transition state analogues • These drugs are enzyme inhibitors, mimicking the crucial features of the transition state but stable to enzymatic reaction

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    Description

    Test your knowledge on Drug-receptor interactions and Isosteres from Lecture 2 of MSOP1016 - The Science of Medicine 3 at Medway School of Pharmacy. Topics include Isosteres/Bioisosteres, Chapter 13 sections 13.1.15 & 13.3.7, and Chapter 14 from the book 'An introduction to medicinal chemistry' by Graham Patrick.

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