Bétagalaktózidáz

Bétagalaktózidáz, also known as lacZ, is an enzyme that catalyzes the hydrolysis of beta-galactosides into their constituent parts, glucose and galactose. It is a crucial enzyme in the metabolic pathway for the breakdown of lactose, a sugar commonly found in milk. In many organisms, including bacteria like Escherichia coli, bétagalaktózidáz is encoded by the lacZ gene.

The primary function of bétagalaktózidáz is to cleave the glycosidic bond in lactose. This reaction is essential for organisms that utilize lactose as an energy source. Without bétagalaktózidáz, lactose cannot be efficiently broken down and metabolized. The enzyme works by adding a water molecule across the beta-glycosidic bond, yielding one molecule of glucose and one molecule of galactose.

In molecular biology, the lacZ gene is widely used as a reporter gene. Its expression can be easily detected by its enzymatic activity. When the lacZ gene is fused to a promoter of interest, the expression of bétagalaktózidáz indicates that the promoter is active. The presence of the enzyme can be visualized using chromogenic substrates, such as X-gal, which produce a blue color when cleaved by bétagalaktózidáz. This blue color serves as a visual indicator of gene expression or successful DNA insertion in cloning experiments. The absence of blue color can indicate that the gene of interest has been successfully inserted into a vector, disrupting the lacZ gene and preventing bétagalaktózidáz production.