Proteins are defined as large biomolecules, or macromolecules, consisting of one or more long chains of amino acid residues. They perform a variety of important functions in cells, such as catalysing metabolic and biochemical reactions, assisting DNA replication, responding to external and internal stimuli, and transporting molecules from one location to another, intra-cellularly or extra-cellularly. This edited book highlights various aspects of protein research, covering five main themes: in vitro characterisations of recombinant protein; proteomic analysis; enzymatic studies; protein bioinformatics viral and mammalian proteins. Several techniques are described, which include 1D and 2D protein electrophoresis, heterologous protein expression, site directed mutagenesis, circular dichroism spectroscopy, in silico docking studies, and immunohistochemistry. The study of proteins is important at fundamental and translational levels in the fields of biomedicine, environmental sciences and industrial applications. The description of laboratory techniques provided in this book will be useful for undergraduate and postgraduate students who are new to the field; advanced researchers may find new ideas on how various techniques are applied.