comment

TECHNICALCOMMENT– transition statelikely to contain an MgF3Commenton“ThePentacovalent analog, rather than to represent the high-energy phosphorane intermediate suggestedin (1). This change in interpretation is crucial,PhosphorusIntermediateofabecause the structural analog can be inter-preted with equal validity as a mimic of thePhosphorylTransferReaction”transition state for a concerted reaction, as aphosphorane intermediate, or as a metaphos-The claim by Lahiri et al.( 1) to have iden- some of the attributes of various Fourier phate species in a dissociative process. Thetified the pentacovalent phosphorus interme- maps described by Lahiri et al.( 1) did not difference between these systems is simply an– moiety.diate of a phosphoryl transfer reaction ad- seem consistent with a PO few tenths of an angstrom in the apical bond3dresses an important, long-disputed problem: Is there an alternative, better interpreta- distances and cannot be resolved solely onwhether the enzyme-catalyzed transfer of tion of these data? The crystallization con- the basis of a model structure. Therefore, wephosphate is a dissociative or associative pro- ditions used by Lahiri et al.( 1) contained believe that the catalytic mechanism of PGM2 and 100 mM NH F. Ourcess. The apparent observation of a pen- 10 mM Mg remains unidentified.4taoxy-phosphorane suggests that the transfer published results (5) have shown that Seeing may be believing (8)—but only– is a good mimic of the ...