Open AccessMechanism and Stereochemistry of 5-Dehydroquinate Synthetase
Author(s) -
Samuel Rotenberg,
David B. Sprinson
Publication year - 1970
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.67.4.1669
Subject(s) - tritium , dehydratase , chemistry , shikimic acid , stereochemistry , elimination reaction , enol , dehydration , biochemistry , enzyme , organic chemistry , catalysis , physics , nuclear physics
3-Deoxy-D-arabino -heptulosonic acid 7-phosphate (DAHP) labeled at C-7 randomly or stereospecifically with tritium and at C-1 with14 C was converted enzymically to 5-dehydroquinate. Tritium of all three substrates was completely retained in 5-dehydroquinate, in accord with formation of a non-ketonizing 6,7-enol intermediate. The 5-dehydroquinates were dehydrated to 5-dehydroshikimate by 5-dehydroquinate dehydratase, which is known to catalyze acis -elimination. Only 5-dehydroquinate derived from [7-3 H](7R )-DAHP lost its tritium in this dehydration, indicating that the configuration at C-7 was inverted in the conversion of DAHP to 5-dehydroquinate.