Enzymes in leaves

REIMHOLZ, R., GEIGER, M., HAAKE, V., DEITING, U., KRAUSE, K.P., SONNEWALD, U., STITT, M., Sucrose phosphate synthase is regulated by metabolites and protein phosphorylation in potato tubers, in a manner analogous to the enzyme in leaves, Planta, 1994,192, 480-488. 

COPPER (In Biological Systems), The activity of copper in plant metabolism manifests itself in two forms 11) synthesis of chlorophyll, and 12) activity of enzymes. In leaves, most of the copper occurs in close association with chlorophyll, but little is known of ns rale in chlorophyll synthesis, other than the presence of cupper is required. Copper is a definite constituent of several enzymes catalyzing oxidation-reduction reactions (oxidases), in which the activity is believed to be due to the shuttling of copper between the +1 and +2 oxidalicm states,... 

Santarius, K. A., and C. R. Stocking Intracellular localization of enzyme in leaves and chloroplast membranes. Permeability to compounds involved in amino acid syntheses. Z. Naturforsch. 24b, 1170 (1969). 

A minimal mechanism for Na, K -ATPase postulates that the enzyme cycles between two principal conformations, denoted Ej and Eg (Figure 10.11). El has a high affinity for Na and ATP and is rapidly phosphorylated in the presence of Mg to form Ei-P, a state which contains three oeeluded Na ions (occluded in the sense that they are tightly bound and not easily dissociated from the enzyme in this conformation). A conformation change yields Eg-P, a form of the enzyme with relatively low affinity for Na, but a high affinity for K. This state presumably releases 3 Na ions and binds 2 ions on the outside of the cell. Dephosphorylation leaves EgKg, a form of the enzyme with two... 

The uptake and biotransformation of benzene from soil and the atmosphere has been studied in a nnmber of plants. It was shown that in leaves of spinach Spinacia oleraced) the label in -benzene was fonnd in mnconic, fnmaric, snccinic, malic, and oxalic acids, as well as in specific amino acids, and that an enzyme preparation in the presence of NADH or NADPH prodnced phenol (Ugrekhelidze et al. 1997). 

Sulfonylureas are the basis of a large group of herbicides. Cytochrome P450 enzymes in Streptomyces griseolus transform the sulfonylureas by hydroxylation (Omer et al. 1990) leaving the -SO2NHCONH- part of the structure unaltered (Harder et al. 1991). 

A continuous stirred tank reactor has been reported for the hydrolysis of the triglycerides existing in vegetable oil in the presence of the aqueous phase and for synthesis reactions (Table 5). A microfilter can be used to prevent the immobilized enzyme from leaving the reactor. Kawano et al. [115] investigated the hydrolysis of olive oil in octane with Candida cylindracea lipase in aqueous solution in a Vibro Mixer reactor containing vibration plates connected to the crankshaft of a motor and oscillated with fixed rates. 

Jiang, M. and Zhang, J. (2002). Water stress-induced abscisic acid accumulation triggers the increased generation of reactive oxygen species and up-regulates the activities of antioxidant enzymes in maize leaves. Journal of Experimental Botany 53 2401-2410. 

Although LOX from soybean seed is the best characterized of plant LOXs, this enzyme is present in a wide variety of plant and animal tissues (Liavonchanka and Feussner, 2006). The enzyme occurs in a variety of isoenzymes, which often vary in their optimum pH and in product and substrate specificity. Given the occurrence of multiple LOX isoenzymes in soybean leaves and the proposed roles of these enzymes in the plant metabolism, it is possible that individual isoenzymes play specific functions (Feussner and Wasternack 2002). The molecular structure of soybean LOX is the most reported, and four isoenzymes have been isolated (Baysal and Demirdoven 2007). Soy isoenzyme 1 produces 9- and 13-hydroperoxides (1 9) when the enzyme acts on free PUFA at pH 9.0, its optimum pH (Lopez-Nicolas and others 1999). Soy isoenzyme 2 acts on triglycerides as well as free PUFA leading to 9- and 13-hydroperoxide... 

Fructose 1,6-diphosphatase hydrolyzes D-fructose 1,6-diphosphate to give D-fructose 6-phosphate and PO . It is a key enzyme in the gluconeo-genesis pathway. Two divalent metal ions (Mg2+, Mn2+, Zn2+, and Co2+) are involved in catalysis. In the enzyme isolated from pork kidney the metal-metal distance accounts to 3.7 A [12]. A reaction mechanism similar to that of protein phosphatase 1 was proposed, but leaving group stabilization by metal coordination of the ester oxygen atom appears to be absent (Figure 6) [12]. 

Once you inhale //-hexane, it goes into your bloodstream and is carried to all the organs in your body. Enzymes in your liver break down //-hexane. If you are exposed to high concentrations of //-hexane over a long period, one of these breakdown products may cause damage to your nervous system. Most of these breakdown products leave your body in the urine within a day or two. //-Hexane and its breakdown products are not stored in your body. 

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