DNAglykosylaasit

DNAglykosylaasit, also known as DNA glycosylases, are a crucial class of enzymes involved in DNA repair. They play a central role in the base excision repair (BER) pathway, a major mechanism for removing damaged or modified bases from the genome. These enzymes work by recognizing and cleaving the glycosidic bond that links a damaged or altered base to the deoxyribose sugar backbone of DNA.

There are various types of DNA glycosylases, each specialized to recognize and remove specific types of DNA damage. For instance, some glycosylases target oxidized bases, such as 8-oxoguanine, which can lead to mutations if left unrepaired. Others are responsible for removing alkylated bases, deaminated bases (like uracil in DNA), or bases that have undergone other forms of chemical modification.

The action of a DNA glycosylase creates an abasic site, also known as an apurinic or apyrimidinic (AP) site, where the base has been removed but the sugar-phosphate backbone remains intact. This abasic site then serves as a recognition point for other enzymes in the BER pathway, such as AP endonuclease, which cleaves the DNA backbone. Subsequent steps involve inserting a new nucleotide and ligating the DNA strand to restore the original sequence.

The precise and efficient action of DNA glycosylases is vital for maintaining genomic integrity and preventing the accumulation of mutations that can lead to diseases like cancer. Defects in DNA glycosylase activity can result in increased susceptibility to mutagens and a higher risk of disease.