ivePRAI: the "Golden" Product

Although analysis shows that ivePRAI is more similar to IGPS (90% sequence identity) than PRAI (28% sequence identity), ivePRAI possesses only PRAI activity; it no longer expresses any IGP synthetase activity.

Dividing the K_m for wild-type PRAI (K_m = 0.32mM) by the K_m for ivePRAI (K_m = 4.9mM) shows that ivePRAI binds CdRP approximately fifteen times better than wild-type PRAI (Table 1). The binding site of ivePRAI is predicted to be more similar to the binding site of IGPS than it is to the binding site of PRAI (as far as location and orientation of the binding site is concerned), even though ivePRAI has the same activity as PRAI. Comparing the catalytic activity of the enzymes shows that ivePRAI is also 6 times more catalytically active than PRAI: k_cat/K_m for ivePRAI is six times greater than k_cat/K_m for PRAI (Table 1).

Table 1 (After Altamirano, Table 1)

[Overview] [Background] [Structural Modification] [Selection] [ivePRAI] [Implications] [References] [Links]

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Nikki Jarrett, 11/20/00
Biochemistry 462bH, Dr. D. Bourque