Enzymes

Enzymes

• Enzymes are primarily proteins that function as biological catalysts essential for cellular processes.

  • Catalyst: Molecules that enhance the rate of chemical reactions without being altered or consumed in the process.

• While most enzymes are proteins, some are RNA molecules.

  • Ribozyme: An RNA enzyme, such as one that joins amino acids in the ribosome.

Induced Fit Model

• Enzyme activity relies on the precise physical fit between the enzyme and its substrate.

  • Substrate: The reactant molecule that is catalyzed by the enzyme.

  • Active Site: The specific location on the enzyme where the substrate binds.

• Shape is critical in determining an enzyme's function.

  • The enzyme's shape arises from the sequence of its amino acids, which is dictated by DNA.

Enzyme Activity

• Chemical reactions can occur without enzymes but require significantly more energy.

  • Activation Energy: The energy threshold required for a reaction to take place, which is reduced in the presence of enzymes.

• Substrate: The molecule that the enzyme acts upon.

• Enzymes typically have names ending with “-ASE”.

  • Examples of enzymes:

    • Sucrase: Breaks down sucrose.

    • Amylase: Breaks down starch.

• Common names of simple sugars often end with “-OSE”.

Reaction Rates

• Each enzyme has an optimal temperature and pH range for maximum activity.

  • Extreme deviations in temperature or pH can cause denaturation, altering the enzyme's shape and function.

• The reaction rate can be influenced by substrate and enzyme concentrations:

  • If increasing substrate concentration raises the reaction rate, substrate is limiting.

  • If increasing enzyme concentration raises the reaction rate, then the enzyme is limiting.

Enzyme Graphs Questions

• Identify the optimal pH for the enzyme pepsin.

• Determine the optimal pH for trypsin.

• If the pH is 6.3, ascertain which enzyme would function best under those conditions.