Question

Examine the structure and mechanism of Lysozyme. If the glutamate and aspartate residues were reversed, would you expect the enzyme to still be active? Why or why not?

Answer 1

Yes the enzyme will be still active, the reason for that is the glumate present at the 35th position in the peptide of the enzyme, attacks the glycosydic bond through the proton. Similarly the Asp at the 52th position stabilizes the oxonium ion through its negative charge. The reason for this is that the Glu-35 has carboxyl group of its side chain neutral which is because of its surrounding amino acids. Thus if aspartic acid is present at its place it too would be in the same form.

Similarly if aspartic acid at position 52 which has side chain negatively charged which stabilises the oxonium ion is replaced with the glutamic acid its side chain too will exist as the negatively charged side chain just like the aspartate.

As from above both the amino acids have nearly the same properties and can act at both positions. Thus if their positions are reversed the will be no effect on the activity of the enzyme.