Table of Contents

ABSTRACT

Enzymes are proteins responsible for conducting different cell activities. Some enzymes work together in a pathway to produce one or more products. These different proteins are built of an amino acid chain. Their difference in structure and function is based on their difference in amino acid sequence, thus in their 3D structure. An effective change in a protein structure and function is well represented by changes in its active site, which in turn changes its activity and/or its substrate specificity. Accumulated changes could lead to change in the entire protein function. Similar enzymes have conserved amino acid residues. Conserved amino acids are an interesting subject of research. One amino acid in protein active site could dramatically affect the activity and the specificity of an enzyme (protein). Sickle cell anaemia represents a famous case in which, the change in a single amino acid is the cause of such degenerative disease. The image is not that simple. Changes in amino acids other than the active residues are also affecting the protein activity, specificity, polarity, and so on. That is because such changes affect the 3D structure of the protein, which interferes with the catalytic residue configurations and their fitting to their specific substrate. This is a clear prove that any change in an amino acid will lead to a change in protein’s activity. Changes in DNA are permanent. Changes caused by environmental factors such as pH, temperature, ions, and so on are temporary (in case of correct denature). The environment where a protein exists could be optimized to match the better structure and function. This chapter aims to highlight the different criteria involved in protein structure and function. It covers some important historic stations in the progress of protein science.

Keywords: protein activity, structure and function, Sickle cell anaemia, insulin