期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2010
卷号：107
期号：10
页码：4555-4560
DOI：10.1073/pnas.0910333106
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Prior evidence supporting the direct observation of phosphorane intermediates in enzymatic phosphoryl transfer reactions was based on the interpretation of electron density corresponding to trigonal species bridging the donor and acceptor atoms. Close examination of the crystalline state of {beta}-phosphoglucomutase, the archetypal phosphorane intermediate-containing enzyme, reveals that the trigonal species is not [IMG]f2.gif" ALT="Formula" BORDER="0">, but is [IMG]f1.gif" ALT="Formula" BORDER="0"> (trifluoromagnesate). Although [IMG]f1.gif" ALT="Formula" BORDER="0"> complexes are transition state analogues rather than phosphoryl group transfer reaction intermediates, the presence of fluorine nuclei in near-transition state conformations offers new opportunities to explore the nature of the interactions, in particular the independent measures of local electrostatic and hydrogen-bonding distributions using [IMG]f3.gif" ALT="Formula" BORDER="0"> NMR. Measurements on three [IMG]f4.gif" ALT="Formula" BORDER="0">-sugar phosphate complexes show a remarkable relationship between NMR chemical shifts, primary isotope shifts, NOEs, cross hydrogen bond [IMG]f5.gif" ALT="Formula" BORDER="0"> scalar couplings, and the atomic positions determined from the high-resolution crystal structure of the [IMG]f6.gif" ALT="Formula" BORDER="0"> complex. The measurements provide independent validation of the structural and isoelectronic [IMG]f1.gif" ALT="Formula" BORDER="0"> model of near-transition state conformations.
关键词：19F NMR ; phosphoryl transfer enzyme ; transition state analogue ; trifluoromagnesate
