Exyloglikozidazami

Exyloglikozidazami, also known as xyloglucan endotransglycosylases (XETs), are a class of enzymes belonging to the glycoside hydrolase family 16. These enzymes play a crucial role in plant cell wall metabolism, specifically in the modification and rearrangement of xyloglucan, a major structural polysaccharide in the primary cell walls of dicotyledonous plants and some gymnosperms.

Xyloglucan acts as a cross-linking agent, tethering cellulose microfibrils within the cell wall. XETs function by cleaving a xyloglucan chain and then rejoining the cleaved fragments to another xyloglucan molecule, often at a different point in the polysaccharide. This process, termed "endotransglycosylation," does not result in a net change in the amount of xyloglucan but rather modifies its structure and distribution.

The activity of XETs is critical for cell wall expansion, a process essential for plant growth, development, and responses to environmental stimuli. By loosening the xyloglucan network, XETs allow for the slippage of cellulose microfibrils, enabling the cell to enlarge. This enzyme family is involved in various developmental processes, including seed germination, root elongation, leaf expansion, and fruit ripening. Research suggests that XETs are also implicated in plant defense mechanisms against pathogens and in adaptations to stress conditions. The precise mechanisms and regulation of XET activity are areas of ongoing investigation in plant biology.