D. Heacock et al., SYNTHESIS AND AMINOACYL-TRANSFER-RNA SYNTHETASE INHIBITORY ACTIVITY OF PROLYL ADENYLATE ANALOGS, Bioorganic chemistry, 24(3), 1996, pp. 273-289
Two nonhydrolyzable prolyl adenylate analogs, 5'-O-[N-(L-prolyl)-sulfa
moyl]adenosine (L-PSA) and 5'-O-[N-(D-prolyl)-sulfamoyl] adenosine (D-
PSA), were prepared in three steps from 2',3'-di-O-isopropylideneadeno
sine. Both of these compounds inhibited the in vitro activity of Esche
richia coli and human prolyl-tRNA synthetase (ProRS). The human enzyme
used in this study was derived from the carboxy-terminal domain of th
e multifunctional human EPRS gene. The K-i(ATP) values for L-PSA, dete
rmined using the ATP-PPi exchange assay, are very similar for both syn
thetases (approximate to 1-2 nM). The K-i(Pro) values, on the other ha
nd, vary approximately seven-fold between the two synthetases (0.6 nM
for human and 4.3 nM for E. coli). The K-i values measured for the D-P
SA analog are much higher (51-470 nM) for all cases examined; however,
the same species-specific differences are observed with respect to K-
i(Pro). These results indicate possible structural differences in or n
ear the active sites of the two enzymes that may be exploited in the f
uture design of compounds that function as species-specific synthetase
inhibitors in vivo. (C) 1996 Academic Press, Inc.