Chemistry Reference
In-Depth Information
Figure 5.10 Abbreviated mechanism for transamination reactions promoted
by pyridoxal-based catalysts.
spectrometry verified the catalytic function (Schiff base formation) of the introduced
lysine residue in the reaction process. Significantly, in a study of rate versus pH,
IFABP-PX60 gave a rate that decreased monotonically with increasing pH while
the lysine mutants exhibited a bell-shaped profile with a maximum rate near pH
7.5. Taken together, these results provide compelling evidence that the lysines parti-
cipate directly in the reaction and that features of enzymatic processes, including cova-
lent catalysis, can be mimicked successfully.
Figure 5.11 Stereo representation of a model of IFABP-PXK51. The
overall protein structure is shown with C
60
and the pyridoxal linked via a
disulfide bond. The pyridoxal aldehyde group is bonded through a Schiff
base to K
51
. Color scheme: Protein secondary structure (green), carbon
(white), oxygen (red), nitrogen (blue), sulfur (orange).
