The Protein Man's Blog | A Discussion of Protein Research

Protein Purification

When investigating a particular protein of interest, the first step is to separate it from the non-protein components and from all the other proteins in the complex sample mixture (cell, tissues, or whole organisms) by exploiting differences in size, physical and chemical properties, binding affinity, and biological activities of individual proteins. 

Basically, protein purification allows researchers to identify and examine the properties of the protein of interest, including its structure, function, and interactions. When classified according to purpose, protein purification can either be preparative or analytical. 

Proteinase K is a serine protease, the presence of a catalytic triad characterizes serine proteases, the catalytic triad is a cluster of three amino acids that make the catalytic center and consists of serine, aspartic acid, and histidine amino acids, which can often vary but all of these enzymes have a nucleophile serine and the same catalytic mechanism. Proteinase K has a catalytic triad consisting of Ser 224, His 69, and Asp 39. The substrate recognition sites are made up of peptide chains, 99-104 and 132-136.