Timothy M. Squires

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We report the discovery of a new hydroxylated abscisic acid (ABA) metabolite, found in the course of a mass spectrometric study of ABA metabolism in Brassica napus siliques. This metabolite reveals a previously unknown catabolic pathway for ABA in which the 9'-methyl group of ABA is oxidized. Analogs of (+)-ABA deuterated at the 8'-carbon atom and at both(More)
Structural analogues of the phytohormone (+)-abscisic acid (ABA) have been synthesized and tested as inhibitors of the catabolic enzyme (+)-ABA 8'-hydroxylase. Assays employed microsomes from suspension-cultured corn cells. Four of the analogues [(+)-8'-acetylene-ABA, (+)-9'-propargyl-ABA, (-)-9'-propargyl-ABA, and (+)-9'-allyl-ABA] proved to be suicide(More)
We have described a simple, reliable and rapid method of extracting and partially purifying the phytohormone (+)-abscisic acid and its catabolites for liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS-MS) analysis. Lyophilized tissue samples were powdered by high-speed agitation with ceramic beads for 5 s. Metabolites were(More)
An anthracenone analogue of abscisic acid (ABA) was synthesized as a potential photoaffinity reagent and tested for biological activity. Reaction between 10,10'-dimethoxy-9-anthrone with two equivalents of the lithiated dianion of cis-3-methylpent-2-en-4-yn-1-ol afforded an acetylenic alcohol key intermediate. Subsequent reduction of the triple bond,(More)
The total length of a linear structure contained in an unbounded, transparent reference space can be estimated from ‘total vertical projections’ obtained by rotating the linear structure about an arbitrary ‘vertical’ axis, and projecting the linear structure onto a plane parallel to the axis of rotation. The total number of intersections between cycloid(More)
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