Question

1. number and describe the six steps of enzyme action shown on the figure above.
2. what is meant by induced fit? how is it shown in the figure in question 22?
3. explain how protein structure is involved in enzyme specificity.
4. enzymes use a variety of mechanisms to lower activation energy. describe four of these mechanisms.

Explanation:

1. Without the figure, a general description of enzyme - action steps could be: 1) Substrate approaches the enzyme. The substrate is the molecule on which the enzyme acts. 2) Substrate binds to the active - site of the enzyme. The active - site is a specific region on the enzyme. 3) Enzyme - substrate complex is formed. This complex is a temporary structure. 4) Chemical reaction occurs within the complex, transforming the substrate into products. 5) Products are formed and released from the active - site. 6) Enzyme is free to bind another substrate molecule.
2. Induced fit refers to the conformational change in the enzyme's active - site upon substrate binding. It allows a more precise and stable interaction between the enzyme and the substrate. In a figure, it might be shown as the enzyme's active - site changing shape to better accommodate the substrate.
3. The unique three - dimensional structure of a protein (enzyme) determines its active - site shape. Only substrates that can fit into this specific active - site shape can bind, thus determining enzyme specificity.
4. Four mechanisms enzymes use to lower activation energy are: 1) Acid - base catalysis: Enzyme residues act as acids or bases to facilitate bond breakage or formation. 2) Covalent catalysis: The enzyme forms a temporary covalent bond with the substrate. 3) Metal ion catalysis: Metal ions in the active - site participate in the reaction. 4) Proximity and orientation effects: The enzyme brings substrates close together and in the correct orientation for the reaction to occur.

Answer:

1. General steps: 1) Substrate approaches enzyme. 2) Substrate binds to active - site. 3) Enzyme - substrate complex forms. 4) Reaction occurs. 5) Products are released. 6) Enzyme is free.
2. Induced fit is conformational change of active - site upon substrate binding. Shown as active - site shape change in figure.
3. Protein's 3 - D structure determines active - site shape, thus specificity.
4. Acid - base catalysis, covalent catalysis, metal ion catalysis, proximity and orientation effects.