Such specific CGTase variants have not yet been engineered,
although, CD ratios are strongly influenced by mutations at
the -3/-6/-7 donor subsites.
The -1/-2 donor subsites are
crucial for catalytic activity. Strong enzyme-substrate
interactions exist at subsite -6 while a lack of these
interactions at subsites -4/-5 ensures the binding of a
substrate long enough for CD formation. Engineering CD
specificity by mutating conserved acceptor subsites residues
of CGTases is not advisable as this typically results in highly
hydrolytic CGTases (Table 2) that form small quantities of
CDs