Abscisic acid properties

In the natural world, carotenoid oxidation products are important mediators presenting different properties. Volatile carotenoid-derived compounds such as noriso-prenoids are well known for their aroma properties. Examples include the cyclic norisoprenoid P-ionone and the non-cyclic pseudoionone or Neral. Carotenoid oxidation products are also important bioactive mediators for plant development, the best-known example being abscisic acid. Apo-carotenoids act as visual and volatile signals to attract pollination and seed dispersal agents in the same way as carotenoids do, but they are also plant defense factors and signaling molecules for the regulation of plant architecture. 

The effect of pH. Okamoto and Nakazawa (90) have observed an unexpected decrease in the retention of abscisic acid enantiomers when the pH of the mobile phase was lowered from 4.0-3.5. This was attributed to a change in the properties of the protein. Ovomucoid has been shown to undergo a low-pH transition, during which the protein adopts a more folded and ordered configuration (99,101). 

ABSTRACT More than 100 abscisic acid (ABA) analogs have been reported so far. Some were synthesized to clarify structure-activity relationships, and others were developed as tools for investigating the molecular mechanism of ABA action. These analogs, especially those that can be useful tools for studying ABA reception and catabolic inactivation, are summarized together with their design concepts, structural properties and bioactivities. 

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. 

The I.U.P.A.C.-I.U.B. tentative nomenclature for carotenoids has been widely published. Recent progress in carotenoid and related fields has appeared in the proceedings of the Phytochemical Society Symposium held in Liverpool in 1970. In particular, advances in carotenoid chemistry are surveyed by Liaaen-Jensen the distribution and taxonomic significance of algal carotenoids by Goodwin and studies on abscisic acid by Milborrow. A symposium on sporopollenin has been published which includes a discussion on its possible origin from carotenoids. The properties of yeast pigments are summarized in a chapter written by Chichester and co-workers." The obituary of Professor P. Karrer outlines some of his many contributions to carotenoid chemistry. Advances in the biosynthesis of carotenoids and polyterpenoids are dealt with in the next chapter. 

Xanthoxin an endogenous growth regulator, oe-curring widely in higher plants and possessing inhibitory properties similar to those of abscisic acid. It occurs in both the cis,trans, and in the biologically less active trans,trans form. Plant tissues can probably convert cis,trans-X. into (/J)-(-i-)-abscisic acid. 

Davison RM (1965) Some properties of a plant growth inhibitor present in xylem sap of woody plants. Austr J Biol Sci 18 475-486 Davison RM, Young H (1973) Abscisic acid content of xylem sap. Planta 109 95-98 Davison RM, Young H (1974) Seasonal changes in the level of abscisic acid in xylem sap of peach. Plant Sci Lett 2 79-82... 

Abscisic acid (ABA), 784-785 Absorption measurement, 208 Acid dyes, 1015,1016 Adsorbent gradient, ISO Adsorbents, 17 Adsorption chromatography aluminas and, 17,107 Kowalska model of, 63-64 O ik model of, 61-62 Scott-Kucera model of, 62-63 silica gels and, 17,104 Synder-Soczewinski model of, 60 Alcoholic products, dyes from, 1005 Alkaloids from plants, 1040 pyrrolizidine, 1036-1040 Aluminas, 17,106-107 adsorption chromatography and, 107 partition chromatography and, 107 physical and chemical properties, 106-107 for separation of carbohydrates, 494 Amikacin, 458-461... 

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