Great Britain 9 F - n . m . r . studies of 3 ' , 5 ' - difluoromethotrexate binding to Latobacillus casei dihydrofolate reductase
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چکیده
19F-n.m.r. spectroscopy was used to study the binding of 3',5'-difluoromethotrexate to dihydrofolate reductase (tetrahydrofolate dehydrogenase) from Lactobacillus casei. The benzoyl ring of the bound difluoromethotrexate was found to 'flip' about its symmetry axis, and the rate (7.3 x 10s3-1 at 298 K) and activation parameters for this process were determined by lineshape analysis ofthe 19F-n.m.r. spectrum at a series of temperatures in the range 273-308K. The contributions to the barrier for this process
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