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Specificity Constant definitions

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  • Specificity Constant
    Ratio reflecting catalytic efficiency at low substrate concentrations, combining turnover rate and substrate affinity.
  • K_cat
    Value indicating the maximum number of substrate molecules converted to product per enzyme per second under saturating conditions.
  • K_M
    Measure of substrate concentration at which an enzyme operates at half its maximal velocity, reflecting binding affinity.
  • Catalytic Efficiency
    Overall effectiveness of an enzyme in converting substrate to product, especially relevant at physiological substrate levels.
  • Saturating Substrate Concentration
    Condition where all enzyme molecules are bound to substrate, allowing measurement of maximal catalytic activity.
  • Non-saturating Substrate Concentration
    Condition where substrate levels are below saturation, typical in cells, revealing enzyme preference and efficiency.
  • Enzyme-Substrate Complex
    Temporary association formed when an enzyme binds its substrate, essential for catalysis.
  • Binding Affinity
    Strength of interaction between enzyme and substrate, influencing how efficiently the enzyme works at low substrate levels.
  • Diffusion-Controlled Limit
    Maximum rate at which enzyme and substrate can associate, determined by how fast molecules diffuse in water.
  • Catalytically Perfect Enzyme
    Enzyme that converts substrate to product almost instantly upon binding, reaching the diffusion-controlled maximum efficiency.
  • Chymotrypsin
    Peptidase with a preference for aromatic amino acids, used to illustrate substrate selectivity and specificity constant.
  • Aromatic Amino Acids
    Substrates like phenylalanine, tyrosine, and tryptophan, highly preferred by certain enzymes such as chymotrypsin.
  • Association Rate Constant (K_1)
    Rate at which free enzyme and substrate combine, setting the upper limit for specificity constant.
  • Turnover Number
    Maximum number of substrate molecules processed by a single enzyme molecule per second, synonymous with K_cat.
  • Michaelis Constant
    Substrate concentration at which enzyme activity is half-maximal, inversely related to binding affinity.