title: Stereochemistry of the acyl dihydroxyacetone phosphate acyl exchange reaction.
abstract: The fatty acid of acyl dihydroxyacetone phosphate can be exchanged enzymatically for another fatty acid. It has been shown that this reaction proceeds by cleavage of the oxygen bound to C-1 of the dihydroxyacetone phosphate (DHAP) moiety rather than by the more common cleavage at the acyl to oxygen bond. In the present study, the stereochemistry of this reaction was defined further; using deuterated substrates and fast atom bombardment-mass spectrometry, it was shown that the fatty acid exchange involves the stereospecific labilization of the pro-R hydrogen at C-1 of the DHAP moiety of acyl DHAP. The mechanism of ether bond formation, in which acyl DHAP is converted to O-alkyl DHAP, also proceeds via labilization of the pro-R hydrogen and cleavage of the fatty acid at the C-1 to oxygen bond. In addition, other workers have provided evidence that the enzyme responsible for the exchange reaction is O-alkyl DHAP synthetase. Therefore, the present results support the hypothesis that the acyl exchange is the reverse reaction of the first step in O-alkyl DHAP synthesis; in both of these reactions the pro-R hydrogen of C-1 of the DHAP moiety of acyl DHAP and the fatty acid moiety are labilized with cleavage of the fatty acid at the DHAP C-1 to oxygen bond.
authors.affiliation: Department of Medicine, University of Texas Health Science Center, San Antonio 78284.
authors.forename: S J
authors.initials: SJ
authors.lastname: Friedberg
authors.forename: N
authors.initials: N
authors.lastname: Satsangi
authors.forename: S T
authors.initials: ST
authors.lastname: Weintraub
mesh_terms: D004098:Dihydroxyacetone / Q000031:analogs & derivatives / Q000737:chemistry; D004099:Dihydroxyacetone Phosphate / Q000737:chemistry* / Q000378:metabolism; D005227:Fatty Acids / Q000737:chemistry; D006859:Hydrogen / Q000737:chemistry; D008968:Molecular Conformation; D016339:Spectrometry, Mass, Fast Atom Bombardment
chemical_list: D005227:Fatty Acids; C053176:heptadecanoyl dihydroxyacetone phosphate; D004099:Dihydroxyacetone Phosphate; D006859:Hydrogen; D004098:Dihydroxyacetone