Restriksjonsseter

Restriksjonsseter, also known as restriction enzymes, are specialized proteins that play a crucial role in molecular biology, particularly in genetic engineering and biotechnology. These enzymes are naturally produced by bacteria as a defense mechanism against foreign DNA, such as that from bacteriophages (viruses that infect bacteria). By recognizing specific nucleotide sequences, typically four to eight base pairs long, restriction enzymes cleave the DNA at or near these recognition sites, effectively breaking it into fragments.

The recognition sequences for restriction enzymes are often palindromic, meaning they read the same backward on the complementary strand. For example, the enzyme EcoRI recognizes the sequence GAATTC and cuts between the G and A nucleotides on each strand. This specificity allows scientists to target and manipulate DNA with precision. Restriksjonsseter are classified based on the position where they make their cuts relative to the recognition site, such as blunt-end cutters, which produce straight ends, or sticky-end cutters, which create overhanging sequences that can base-pair with complementary sequences.

In laboratory settings, restriction enzymes are widely used in techniques like DNA cloning, where they facilitate the insertion of genes of interest into vectors such as plasmids. They are also essential for constructing DNA libraries, genetic mapping, and DNA fingerprinting. The discovery and characterization of these enzymes in the 1970s revolutionized molecular biology, enabling advancements in fields like medicine, agriculture, and biotechnology. Today, thousands of restriction enzymes with diverse recognition sequences are commercially available, catering to a wide range of research and industrial applications.