Enzymes and catalysts

Enzymes are catalysts that facilitate biological reactions and are crucial for biochemical processes. They are often metaphorically described as buildings whose main role is to protect the structure where reactions occur, primarily the reaction pocket.

  1. Basic Enzyme Structure
       - Enzymes are made up of proteins, which protect key amino acids involved in catalyzing reactions.
       - Example: Chymotrypsin, a serine protease, is a digestive enzyme produced in the small intestine.
       - Enzyme naming conventions: 'A' indicating an enzyme; the rest of the name refers to the substrate and reaction type.

  2. Active Site and Catalytic Triad
       - The reaction pocket contains three critical amino acids that actively participate in catalysis, often through hydrogen bonding and ionic interactions (salt bridges) to strain the substrate bonds.
       - The enzyme configuration (e.g., alpha helix, beta sheets) supports maintaining the active site’s structure.    

  3. Energy Profile of Reactions
       - Enzymes lower the activation energy needed for reactions by providing an alternative pathway rather than reducing the transition state energy.
       - The Gibbs Free Energy chart indicates that catalyzed reactions have a lower transition state energy than uncatalyzed ones, significantly increasing reaction rates.
       - In certain cases, enzymes can increase reaction rates by millions of times as compared to reactions without catalysts.

  4. Mechanisms of Action
       - Enzymes can undergo conformational changes (e.g., allosteric effects) when substrates bind, changing their shape to facilitate the reaction.
       - Mechanism types:
         - Ordered mechanism: Substrates enter in a specific sequence.
         - Random mechanism: Substrates can enter in any order.
         - Ping Pong mechanism: Substrate exchange occurs where one substrate is modified, and then another substrate interacts with an altered enzyme.

  5. Example of Ping Pong Mechanism
       - Example involves non-essential amino acids where an amino group is removed from one substrate and attached to another, demonstrating the enzyme's ability to mediate these transformations efficiently.

In summary, enzymes are vital proteins that not only enhance the speed of biochemical reactions through catalytic actions but also adopt various mechanisms to achieve these transformations without being consumed in the process.