The are a group of fish thought to be ancestral to amphibians. cartilaginous fish crossopterygians ray-finned fish african lungfish

an active site is a region that is present on an enzyme where the reactants or the substrate molecules we can say bind and experience a chemical reaction. the substrate is basically a reactant whose concentration is changing and that is converting into a product after binding at the active site of an enzyme

creative diagnostics provides a protocol for total protein extraction based on ripa which is widely used.