Genetic engineering is the technique of creating manipulations at the gene level. These manipulations results in the production of desired characteristics. Genetic engineering can also be used to design genes which produce proteins even in the absence of activators.
The natural enzyme is only active in presence of the enzyme serine-threonine kinase responsible for catalysis of the phosphorylation of alcoholic group of serine and threonine residues. The alcoholic group of serine participates in hydrogen interactions with other groups.
The ionic groups are introduced with phosphorylation and these groups then form ionic bonds. The other group present in the protein structure further changes the protein conformation and thus has a profound effect on tertiary structure.
Hence, it activates the enzyme but when the phosphate groups are hydrolysed, it gives the alcoholic groups of serine back. This leads to deactivation of the enzyme when it returns to its original inactivated form. While the enzyme produced by replacing the residues of serine with that of glutamate through genetic engineering is permanently active.
Since the residues of glutamate (?CH2CH2CO2?) are ionized carboxylate groups, thus, phosphorylation does not take place for the activation of enzyme. Hence, the mutated enzyme forms similar ionic interactions due to the ionized groups on glutamate residues. Therefore, the enzymes remain active permanently and there is no way to remove the ionic charge.