Abscisic acid racemic

Finally, there are some examples for reduction of various compounds, which are of biochemical interest. Racemic abscisic acid was reduced with Aspergillus niger affording (—)-(l/5 ,2// )-2/,3/-dihydroabscisic acid with >95% ee (equation 43)117. 

Racemic cis- and tran.s-nor-abscisic acid (132) and (133) have been prepared in five steps from the protected hydroxy-ketone (134) and the acetylene (135). Reaction between the dianion of 3-methylbut-2-enoic acid (136) and... 

Finally, the enantioselective reduction of racemic abscisic acid (ABA) with Aspergillus niger has been explored107. 

The immunoaffinity chromatography of auxins is carried out in the same way. Effective immunosorbents have been described for antibodies prepared to each of the three types of lAA-hapten-protein conjugates [135-137]. For abscisic add, immunoaffinity chromatography has not only been used to isolate the hormone from plant extracts [138], but also has found use in the enantiomeric separation of commercially available racemic [ H]-abscisic acid [139-140]. 

Abscisic acid (ABA) 3-1 was originally detected because of its growth inhibitory properties. It is now known to play an important role in the control of a-amylase synthesis, and regulation of stomatal aperture during water stress. Phaseic acid (PA) 3-3 is an important metabolite of ABA. Over a hundred derivatives of ABA are known, activity correlations have been reviewed, and the difficulty of drawing firm conclusions due to differences in uptake, metabolism and sequestration between the different molecules assayed has been discussed [16-20]. In many correlations, racemates have been used, and it is possible that each enantiomer may be active, have a different type of activity, and/or interfere with the action of the other enantiomer. 

From a biochemical perspective, with the exception of a lower level of starch in the aborting ovaries, no substantial differences between the setting and aborting ovaries were found for protein, soluble carbohydrate, RNA, or DNA, while only minor differences in the pools of free amino acids were noted [8, 12]. Abscisic acid levels in seeds and pod walls of setting and aborting pods also did not vary significantly on a tissue weight basis [17]. Contrary to that, however, ABA levels were found to be lower in bean fruits induced to set by removal of fruits lower on the raceme relative to similar fruits on intact racemes [19]. 

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