Mechanistic Implications of Escherichia coli Galactokinase Structure‐Based Engineering

Engineering GalK: The Escherichia coli galactokinase GalK has been engineered in its active site. The amino acid exchanges Y223F and Y223W broadened the sugar-substrate spectrum to include, among others, 4-deoxy-D-galactose. This finding suggests that the role of Y223 is not primarily hydrogen bonding but rather a hydrophobic stacking to secure the hexopyranose ring in the active site.