Question

RECALL What is the difference between the core enzyme and the holoenzyme?

Short answer

The core enzyme has catalytic activity; the holoenzyme includes additional components for substrate specificity.

Step-by-step solution

- Understand the Core Enzyme

The core enzyme is the part of an enzyme that contains the primary catalytic activity. It is the essential component that carries out the enzyme's main function but lacks specificity for the substrate without additional components.

- Identify the Holoenzyme

The holoenzyme is the complete, functional enzyme that includes the core enzyme along with any additional required subunits or co-factors. These supplementary parts ensure that the enzyme can specifically bind to its substrate and carry out its intended biological function.

- Compare Core Enzyme and Holoenzyme

The core enzyme only has catalytic activity but cannot function optimally without the additional parts that make up the holoenzyme. The holoenzyme possesses both the catalytic activity of the core enzyme and the substrate specificity conferred by the additional components.

Key concepts

core enzyme

The core enzyme is the heart of an enzyme's function. It is the part that carries out the primary reactions, thanks to its catalytic properties. The core enzyme doesn't include any additional components, such as subunits or co-factors, that might be needed for the enzyme to bind specifically to its substrate.
Without these additional parts, the core enzyme can usually only perform basic reactions and has limited functionality.

holoenzyme

The holoenzyme is the complete, active form of an enzyme. It consists of the core enzyme plus all required additional components, like subunits or co-factors. These extra parts confer substrate specificity, allowing the enzyme to interact precisely with its target molecules.
This makes the holoenzyme highly efficient and perfectly suited to perform its biological role.

catalytic activity

Catalytic activity refers to an enzyme's ability to accelerate chemical reactions. This fundamental property is often centered in the core enzyme, which contains the active site responsible for the enzyme’s primary reactions.
However, for the enzyme to work optimally, additional components found in the holoenzyme may be necessary.

substrate specificity

Substrate specificity is the ability of an enzyme to select and bind specifically to its substrate—the molecule upon which it acts. The core enzyme generally lacks this fine-tuned specificity. Instead, this property often comes from additional subunits or co-factors found in the holoenzyme.
Thus, substrate specificity ensures that enzymes catalyze only the intended reactions, avoiding unwanted interactions.

enzyme functionality

Enzyme functionality is the overall performance of an enzyme in catalyzing reactions and interacting with substrates. It involves both catalytic activity and substrate specificity. While the core enzyme provides the essential catalytic activity, the additional components in the holoenzyme help tailor the enzyme to specific substrates.
This collaboration between the core enzyme and its accessory parts ensures the enzyme effectively carries out its biological role.