Plants carbohydrate metabolism

Additional effort to test this regulating role of boron in plant carbohydrate metabolism would be profitable. 

Aldol reactions occur in many biological pathways, but are particularly important in carbohydrate metabolism, where enzymes called aldolases catalyze the addition of a ketone enolate ion to an aldehvde. Aldolases occur in all organisms and are of two types. Type 1 aldolases occur primarily in animals and higher plants type II aldolases occur primarily in fungi and bacteria. Both types catalyze the same kind of reaction, but type 1 aldolases operate place through an enamine, while type II aldolases require a metal ion (usually 7n2+) as Lewis acid and operate through an enolate ion. 

Onodera s professor at that time was Dr. Bunsuke Suzuki, who later became a Professor of the University of Tokyo and was well known as a lipid investigator. Studies on the structure of fibroin, carbohydrate metabolism, separation of triglycerides from animals and plants, an analytic... 

The ozone treatment apparently initiated changes in the pathways of carbohydrate metabolism, with glycolysis being reduced while the activity of the pentose phosphate pathway was increased. Rat lung tissue exposed to ozone also exhibited the ozone-induced depression of GPD and enhancement of G6PD activity (, 10), The activation of the pentose phosphate pathway is a characteristic featiire of diseased plants (11, 12),... 

CN204 Lai, J. ]., C. V. Kumar, M. V. Suresh, M. Indira, and P. L. Vijayammal. Effect of coconut palm wine (Toddy) on carbohydrate metabolism in pregnant rats and fetuses. Plant Foods Hum Nutr 1997 50(1) 71-79. 

Amylose is one component of starch, which is the most abundant carbohydrate storage reserve in plants. Carbohydrates such as starch function as a reservoir of energy for later metabolic use. It is found in many different plant organs, including seeds, fruits, tubers, and roots, where it is used as a source of energy during periods of dormancy and regrowth. 

Carbohydrate metabolism in a typical plant cell is more complex in several ways than that in a typical animal cell. The plant cell carries out the same processes that generate energy in animal cells (glycolysis, citric acid cycle, and oxidative phosphorylation) it can generate hexoses from three- or four-carbon compounds by glu-coneogenesis it can oxidize hexose phosphates to pentose phosphates with the generation of NADPH (the ox-... 

SUMMARY 20.5 Integration of Carbohydrate Metabolism in the Plant Cell... 

The individual pathways of carbohydrate metabolism in plants overlap extensively they share pools of common intermediates, including hexose phosphates, pentose phosphates, and triose phosphates. Transporters in the membranes of chloroplasts, mitochondria, amyloplasts, and peroxisomes mediate the movement of sugar phosphates between organelles. The direction of metabolite flow through the pools changes from day to night. 

This wonderful book—up to date and authoritative—covers all aspects of plant biochemistry and molecular biology. The following chapters cover carbohydrate synthesis in greater depth Malkin, R. Niyogi, K., Chapter 12, Photosynthesis (pp. 568-629) Dennis, D.T. Blakeley, S.D., Chapter 13, Carbohydrate Metabolism (pp. 630-675) Siedow, J.N. Day, DA., Chapter 14, Respiration and Photorespiration (pp. 676-729). 

Potassium [7440-09-7], K, is the third element in the alkali metal series. The name designation for the element is derived from potash, a potassium mineral the symbol from the German name kalium, which comes from the Arabic qili, a plant. The ashes of these plants (a/ qih) were the historical source of potash for preparing fertilizers (qv) or gun powder. Potassium ions, essential to plants and animals, play a key role in carbohydrate metabolism in plants. In animals, potassium ions promote glycolysis, lipolysis, tissue respiration, and the synthesis of proteins (qv) and acetylcholine. Potassium ions are also believed to function in regulating blood pressure. 

In plants, the meristematic tissues in general are particularly rich in potassium, as are other metabolically active regions, such as buds, young leaves, and ioot tips. Potassium deficiency may produce both gross and microscopic changes in the structure of plants. Effects of deficiency reported include leaf damage, high or low water content of leaves, decreased photosynthesis, disturbed carbohydrate metabolism, low protein content and other abnormalities. 

The neutral and nonspecific FDPases may function in nonphotosynthetic carbohydrate metabolism in higher plants. In the germinating castor bean acetate is utilized for the synthesis of sucrose 107, 108), and the presence of the AMP-sensitive FDPase in plant embryo tissues has been demonstrated by Bianchetti and Satirana 109). The changes in levels of this enzyme in response to changes in physiological conditions 109) support a gluconeogenic role for this enzyme. The role of the nonspecific acid FDPase in plant tissues remains unknown. 

A reversible covalent modification that plants use extensively is the reduction of cystine disulfide bridges to sulf-hydryls. Many of the enzymes of photosynthetic carbohydrate synthesis are activated in this way (table 9.3). Some of the enzymes of carbohydrate breakdown are inactivated by the same mechanism. The reductant is a small protein called thioredoxin, which undergoes a complementary oxidation of cysteine residues to cystine (fig. 9.5). Thioredoxin itself is reduced by electron-transfer reactions driven by sunlight, which serves as a signal to switch carbohydrate metabolism from carbohydrate breakdown to synthesis. In one of the regulated enzymes, phosphoribulokinase, one of the freed cysteines probably forms part of the catalytic active site. In nicotinamide-adenine dinucleotide phosphate (NADP)-malate dehydrogenase and fructose-1,6-bis-... 

Paleg, L. (1960). Physiological effects of gibberellic acid. 1. On the carbohydrate metabolism and amylase activity of the barley endosperm. Plant Physiol. 35, 293-299. 

When plants experience anoxic conditions there is a shift in carbohydrate metabolism from an oxidative to a fermentative pathway (Fig. 1). In the absence of oxygen, ATP is generated not by the Krebs cycle but by alcoholic fermentation, i.e. glycolysis and ethanol synthesis. 

Merlo, L., Ghisi, R., Rascio, N., and Passera, C. (1991). Effects of humic substances on carbohydrate metabolism of maize leaves. Can. J Plant Sci. 71,419 425. 

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