For an enzyme to be able to catalyze a reaction, the active site must:

Step 1: Define the Problem

Identify the key components of the question that need to be addressed:

• Understand what is required for an enzyme's active site to catalyze a reaction.

Step 2: Break Down the Problem

Divide the problem into smaller, manageable parts:

• Determine the characteristics of an enzyme's active site.
• Identify the conditions necessary for catalysis.

Step 3: Apply Relevant Concepts

Use appropriate academic theories or formulas to solve each part of the problem:

• Enzymes are biological catalysts that speed up chemical reactions.
• The active site is the region on the enzyme where substrate molecules bind and undergo a chemical reaction.
• For catalysis to occur, the active site must have a specific shape and chemical environment that facilitates the conversion of substrate to product.

Step 4: Analysis, Verify and Summarize

Analyze each part in detail if necessary, carry out the calculations by steps. Verify the calculations result and summarize the findings:

• The active site must be complementary in shape to the substrate, allowing for precise binding.
• It must also have the right chemical properties (e.g., charge, hydrophobicity) to stabilize the transition state and lower the activation energy of the reaction.

Final Answer

For an enzyme to catalyze a reaction, the active site must be complementary in shape and chemical properties to the substrate, allowing it to bind effectively and facilitate the conversion to products.