In higher plants

Furthermore, for each reaction the reaction center was specified, information was given on whether the reaction is reversible or irreversible, and catabolic or anabolic. Finally, it was specified whether a reaction is part of a general pathway or occurs only in unicellular organisms, in higher plants, or in animals (Figure 10.3-21). 

Miscellaneous Alkaloids. Stukimic acid (57) is a precursor of anthranihc acid (28) and, in yeasts and Escherichia coli (a bacterium), anthranHic acid (o-aminobenzoic acid) is known to serve as a precursor of tryptophan (26). A similar but yet unknown path is presumed to operate in higher plants. Nonetheless, anthranHic acid itself is recognized as a precursor to a number of alkaloids. Thus damascenine [483-64-7] (134), C qH NO, from the seed coats of JSHgella damascena has been shown (95) to incorporate labeled anthranHic acid when unripe seeds of the plant are incubated with labeled precursor. 

Fig. 10. Suggested pathway for the biosynthesis of L-ascorbic acid (with retention of configuration) in higher plants based on D-glucose-l- C...

The earliest references to cinnamic acid, cinnamaldehyde, and cinnamyl alcohol are associated with thek isolation and identification as odor-producing constituents in a variety of botanical extracts. It is now generally accepted that the aromatic amino acid L-phenylalanine [63-91-2] a primary end product of the Shikimic Acid Pathway, is the precursor for the biosynthesis of these phenylpropanoids in higher plants (1,2). 

There are two distinct groups of aldolases. Type I aldolases, found in higher plants and animals, require no metal cofactor and catalyze aldol addition via Schiff base formation between the lysiae S-amino group of the enzyme and a carbonyl group of the substrate. Class II aldolases are found primarily ia microorganisms and utilize a divalent ziac to activate the electrophilic component of the reaction. The most studied aldolases are fmctose-1,6-diphosphate (FDP) enzymes from rabbit muscle, rabbit muscle adolase (RAMA), and a Zn " -containing aldolase from E. coli. In vivo these enzymes catalyze the reversible reaction of D-glyceraldehyde-3-phosphate [591-57-1] (G-3-P) and dihydroxyacetone phosphate [57-04-5] (DHAP). 

There are very few examples of naturally occurring pyrazoles. As indicated in the introduction to this chapter, compounds containing the N—N bond are rare in higher plants and the biosynthesis and metabolism of N—N bonds is still unknown. Withasomnine, 4-phenyl-1,5-trimethylenepyrazole (754), was isolated from the roots of Indian medicinal plants, Withania somnifera Dun, and its structure established by physical methods and total synthesis (68TL5707, 82H( 19)1223). 

Unsaturated fatty acids are slightly more abundant in nature than saturated fatty acids, especially in higher plants. The most common unsaturated fatty acid... 

Chlorophyll h, in which the 3-Me group is replaced by -CHO this occurs in higher plants and green algae, the ratio CHI/uChl being-1 3. 

Gilroy, S., Hughes, W. A., and Trewavas, A. J. (1989). A comparison between Quin-2 and aequorin as indicators of cytoplasmic calcium levels in higher plant cell protoplasts. Plant Physiol. 90 482—491. 

Morgan, J.M. (1984). Osmoregulation and water stress in higher plants. Annual Review of Plant Physiology, 35, 299-319. 

Jefferson, R.A., Kavanagh, T.A. Bevan, M.W. (1987). Gus fusions /S-glucuro-nidase as a sensitive and versatile gene marker in higher plants. EMBO Journal, 6, 3901-7. 

Kumar, A. Cocking, E.C. (1987). Protoplast fusion A novel approach to organelle genetics in higher plants. American Journal of Botany, 74, 1289-303. 

Leigh, R.A. (1983). Methods, progress and potential for use of isolated vacuoles in studies of solute transport in higher plant cells. Physiologic Plantarum, 57,390-6. 

Developmental mutants in higher plants. Edited by H. Thomas and D. Grierson... 

Although there are well over 500 different carotenoids in nature (Straub, 1987), all are based on seven different end groups of which only four (P, e, K, /) are foimd in higher plant carotenoids (Fig. 13.1). Cyclisation of the carbon skeleton occurs at one or both ends of the molecule, whilst xanthophylls... 

DEMMIG-ADAMS B, GILMORE A M, and ADAMS w w Jr (1996) In vivo function of carotenoids in higher plants , FASEB J, 10, 403-12. 

Whereas the biosynthesis of chlorophylls a and b in higher plants has been described in detail, the synthesis and regulation of related substances found in less well-known algal groups and lower plants are largely unknown and will be areas of scientific interest in the future. Different and new types of chlorophylls and related substances have been reported and little is known about their possible biological... 

Hortensteiner, S. et ah. The key step in chlorophyll breakdown in higher plants Cleavage of pheophorbide a macrocycle by a monooxigenase, J. Biol. Chem., 273, 15335, 1998. 

Hortensteiner, S., Chlorophyll breakdown in higher plants and algae. Cell. Mol. Life... 

Krautler, B., UnraveUing chlorophyll catabolism in higher plants, Biochem. Soc. Trans., 30, 625, 2002. 

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