Hide–Remazol Brilliant Blue R is a chromogenic substrate specifically designed for assaying protease activity, such as trypsin and other proteolytic enzymes. It consists of Remazol Brilliant Blue R dye covalently bound to insoluble hide powder (collagen), which turns soluble upon enzymatic cleavage, releasing blue-colored fragments measurable spectrophotometrically at around 595 nm. This allows for quantitative determination of protease activity in biochemical research and industrial applications. While the unbound Remazol Brilliant Blue R dye is used in the textile industry for dyeing protein-based fibers like wool and silk, providing vibrant blue shades with excellent fastness due to covalent bonding, this product is the conjugated form optimized for enzymatic studies. It is not typically used as a protein staining agent in gel electrophoresis, where Coomassie Brilliant Blue is more common.