Phenyl β-D Galactopyranoside (P Gal) is a biochemical reagent used primarily for enzyme assays in laboratory settings. This reagent is often utilized to study the activity of β-galactosidase, an enzyme involved in lactose metabolism. When β-galactosidase is present, it hydrolyzes the bond in phenyl β-D galactopyranoside, releasing phenol, which can be detected by colorimetric methods. This 1g sample is ideal for small-scale research and is particularly useful in molecular biology, microbiology, and genetic studies, where it helps to monitor gene expression and enzyme activity in various model organisms.