Many proteins are enzymes that catalyse biochemical reactions and are very important to metabolism. Proteins even have structural or mechanical capabilities, corresponding to actin and myosin in muscle and the proteins within the cytoskeleton, which kind a system of scaffolding that maintains cell shape. Other proteins are essential in cell signaling, immune responses, cell adhesion, and the cell cycle. In animals, proteins are needed within the food regimen to provide the important amino acids that cannot be synthesized.
However, this could also result in complete loss of gene function and thus pseudo-genes. More generally, single amino acid adjustments have restricted …