Proteins (Greek:Proteios,meaning holding first place) are one of the most important group of biomolecules. The quantity and type of proteins show a wide variation between not only among different organisms but also in different organs or parts of the same organism. Proteins perform very vital and diverse roles in organisms. A simple bacterial cell such as Escherichia coli contains more than 5000 different types of proteins. A few of the functions of proteins are enumerated as follows: