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Cofactor definitions

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  • Cofactor
    Non-protein molecule or ion required for enzyme activity, often binding at the active site and influencing catalysis.
  • Apoenzyme
    Inactive enzyme form lacking its essential non-protein component, unable to catalyze reactions.
  • Holoenzyme
    Active enzyme form with its required non-protein component bound, capable of catalyzing reactions.
  • Coenzyme
    Organic molecule, often vitamin-derived, assisting enzyme function and classified as prosthetic group or cosubstrate.
  • Metal Ion
    Charged metal atom, either tightly or loosely bound, crucial for enzyme structure or catalytic activity.
  • Prosthetic Group
    Tightly or covalently attached organic molecule aiding enzyme function, often remaining bound during catalysis.
  • Cosubstrate
    Loosely bound organic molecule, chemically altered during reaction and quickly regenerated, acting as a recyclable helper.
  • Metalloenzyme
    Enzyme containing a tightly bound transition metal ion, essential for catalytic activity.
  • Activator Ion
    Loosely bound alkali or alkaline earth metal ion, temporarily associated with enzymes to enhance activity.
  • Active Site
    Region on an enzyme where non-protein components bind and catalysis occurs, determining specificity and function.
  • Vitamin Precursor
    Nutrient molecule serving as the source for organic helpers in enzyme reactions, often converted to coenzymes.
  • Transition Metal
    Element such as iron, copper, or zinc, commonly found as tightly bound ions in enzyme complexes.
  • Alkali Metal
    Element like sodium or potassium, often loosely associated with enzymes as temporary helpers.
  • Alkaline Earth Metal
    Element such as magnesium or calcium, sometimes acting as loosely bound helpers in enzyme activity.
  • Biotin
    Organic molecule functioning as a tightly bound helper in specific enzyme reactions, derived from vitamin B7.