Retaining glycosidases kinetics

Scheme 5.2 Minimal kinetic scheme for a retaining glycosidase. The double displacement reaction involves two enzyme-substrate complexes, the second of which is commonly (but not always) a glycosylated enzyme.

The minimal kinetic scheme for a retaining glycosidase is given in Scheme 5.2. This scheme gives rise to expressions for kcat, and as shown in eqns... 

Figure 5.38 Burst kinetics showing liberation of aglycone during the establishment of a steady state during hydrolysis of a snbstrate by a retaining glycosidase, when the hydrolysis of the glycosyl-enzyme is rate determining. The glycone was fluorinated, so the experiment was performed in a conventional spectrometer (note time-scale). Note the burst of 0.03 absorbance units.

A direct comparison of the kinetic data for the E217Q mutant with those reported for other acid/base mutants of retaining P-glycosidases is difficult, due... 

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