szubsztrátspecifikusságot

Substrate specificity refers to the ability of an enzyme to catalyze a reaction with only one or a very limited number of related substrates. This selectivity is a fundamental characteristic of enzymes, arising from the precise three-dimensional structure of their active site. The active site is a region on the enzyme where the substrate binds and the chemical reaction takes place. Its shape, size, and chemical properties are complementary to the substrate, much like a lock and key. This complementarity ensures that only the correct substrate can bind effectively and undergo catalysis.

The concept of substrate specificity was famously illustrated by Emil Fischer's lock-and-key model of enzyme action in 1894. While this model is a useful analogy, it's important to note that enzyme active sites are not entirely rigid. The induced-fit model, proposed by Daniel Koshland in 1958, suggests that the active site can undergo slight conformational changes upon substrate binding, leading to a tighter fit and facilitating catalysis.

Substrate specificity is crucial for maintaining metabolic pathways. By ensuring that each enzyme acts on a specific substrate, cells can control and regulate biochemical reactions efficiently, preventing unwanted side reactions and maintaining order within the complex cellular environment. This specificity allows for the precise control of biological processes, from DNA replication and protein synthesis to energy production and waste removal. Variations in substrate specificity can occur due to mutations in the enzyme's gene, leading to altered amino acid sequences and consequently, a modified active site. This can result in enzymes that accept a broader range of substrates or become completely inactive.