Conversion pathway

A number of proteins containing [3Fe-4S] centers form cubane-like clustes of the type [M,3Fe-4S] (115-120), which were prepared using this facile [3Fe-4S]/[4Fe-4S] conversion pathway. The [3Fe-4S] core present in D. gigas Fdll was the first precursor used for the synthesis of heterometal cores inside a protein matrix, and the first derivative synthesized was the [Co,3Fe-4S] core (121). Similar synthetic products have also been derived in D. africanus Fdlll (118, 119). 

Fig. 9. Jablonsky Diagram for energy conversion pathways of an excited molecule. While fluorescence occurs between states of the same spin, an ISC (inter system crossing) leads to spin inversion and a delay in emission (phosphorescence halftimes from 1CT4 s to minutes or even hours)...

The special feature of the spin crossover process in all bpym-bridged dinuclear compounds studied so far is the occurrence of a plateau in the spin transition curve. A reasonable assumption to account for this observation is that a thermal spin transition takes place successively in the two metal centres. However, it cannot be excluded that spin transition takes place simultaneously in the dinuclear units leading directly from [HS—HS] pairs to [LS-LS] pairs with decreasing temperature. Therefore, two possible conversion pathways for [HS—HS] pairs with decreasing temperature may be proposed [HS—HS]<->[HS—LS]<->[LS—LS] or [HS-HS] [LS-LS]. The differentiation of the existence of the [LS—LS], [HS—LS], and [HS—HS] spin pairs is not trivial and has recently been solved experimentally by utilisation of magnetisation versus magnetic field measurements as a macroscopic tool [9], and by Mossbauer spectroscopy in an applied magnetic field as a microscopic tool [11]. 

Fig. 5.6 C02-savings by use of biofuels made from energy crops according to Schmitz (2003), Quirin et al. (2004), CONCAWE (2006), Hill (2007) and BMELV (2007b). Conversion pathways 1 Straight oil —> Drive 2 Biodiesel —> Drive 3 Grain —> Heat 4 Ethanol —> Drive 5 Ethanol —> Heat Power 6 Ethanol —> Drive 7 Bales —> Heat Power 8 BtL —> Drive 9 Methanol —> Drive 10 Ethanol —> Drive 11 Biogas —> Drive 12 Biogas —> Heat Power 13 Chips — Heat 14 Chips —> Heat Power 15 BtL —> Drive...

Jenkin, M. E., Clement, C., and Ford, I. Gas-to-particle conversion pathways, First annual report on the contract Met2a/1053/Project2, AEA Technology, 1996. 

Figure 9.8 summarizes the different possible conversion pathways and/or uses of bioethanol [83]. Notably, however, a decrease in ethanol cost may open the door to a large range of other possible applications, and there is interest in biorefineries to diversify the possible uses of ethanol so as to decrease dependence on market fluctuations. There is thus the need to rediscover, and improve as well, the catalytic chemistry of ethanol. 

Figure 4 gives an alternative scheme of possible biomass conversion pathways. Depending on the type of available biomasses and the objective products, each biorefinery will implement a different production and conversion scheme. 

Fig. 4 Schematic flowsheet of possible biomass conversion pathways in a biorefinery.

Scheme 1 The inter-conversion pathways during ammonolysis of M0O3 adapted from reference 24...

Nucleotides to be used in biosynthesis are generally converted to nucleoside triphosphates. The conversion pathways are common to all cells. Phosphorylation of AMP to ADP is promoted by adenylate kinase, in the reaction... 

Silberring, J., Castello, M. E., and Nyberg, F. (1992). Characterization of dynorphin A-converting enzyme in human spinal cord. An endoprotease related to a distinct conversion pathway for the opioid heptadecapeptide J. Biol. Chem. 267, 21324—21328. 

Figure 18. Conversion pathway for Lewisite 1 to related species (16)...

Blue transitions are also observed with IR excitation at 1.064 m in Tm3+-doped fluorozirconate fibers. Depending on the pumping power, different up-conversion pathways are identified. For low pumping powers, a four-fold up-conversion process leads to excitation of 1D2 ... 

It has also been suggested that glyoxal has a slow internal conversion pathway available. 

All calculations agree that the twist-boat conformation 4 is more stable than the true boat 5, but the distinction is small and will be different for different six-membered rings. The meta-stable conformation in the chair-chair inter-conversion pathway is best considered as a rapid boat and twist-boat pseudorotation. 28)... 

Glycolysis Is an Energy-Conversion Pathway in Many Organisms... 

We now turn to the fates of the carbon skeletons of amino acids after the removal of the a-amino group. The strategy of amino acid degradation is to transform the carbon skeletons into major metabolic intermediates that can be converted into glucose or oxidized by the citric acid cycle. The conversion pathways range from extremely simple to quite complex. The carbon skeletons of the diverse set of 20 fundamental amino acids are furmeled into only seven molecules pyruvate, acetyl CoA, acetoacetyl CoA, a-ketoglutarate, succinyl CoA, fumarate, and oxaloacetate. We see here a striking example of the remarkable economy of metabolic conversions, as well as an illustration of the importance of certain metabolites. 

Most reports pertinent to Reaction (18) describe experiments with extracts or membrane preparations [117,377-380]. Results indicate involvement of corrinoid as an intermediate methyl carrier [379], and an oxygen-labile enzyme [377], similar to the methanohCoM methyltransferase system (MT ) of M. barkeri[ 5A], that requires ATP-dependent reductive activation for activity. Since M bryantii, M. formicicum [380], and M thermoautotrophicum possess cobalamin CoM methyltransferase activities that resemble the analogous protein MT2 in the methanol to CH3-C0M conversion pathway (see sections 3 and 4.13) [152], a scheme similar to that shown in Reactions (19) and (20) has been envisaged, where CH3-H4MPT replaces methanol in Reaction (28). Three recent reports [117,157,195] provide more information about this system, and are reviewed below. 

The term vitamin C refers to ascorbic add (the fully reduced form of the vitamin) and to dehydroascorbic acid. Removal of one electron from ascorbic acid yields semidehydroascorbic add (ascorbate radical). This form of the vitamin is a free radical it contains an impaired electron. The structures of free radicals are written with large dots. The removal of a second electron yields dehydroascorbic add. Conversion of ascorbate to dehydroascorbate, via the removal of two electrons, can occur imder two conditions (1) with use of ascorbic acid by ascorbate-dependent enz5mies and (2) with the spontaneous reaction of ascorbate with oxygen. Semidehydroascorbate is an intermediate in this conversion pathway. 

Any treatment of wood must take account of the differing accessibilities and reactivities of the principal wood constituents. Further, any chemical or microbial method of breaking down wood has to devise conversion pathways for cellulose, the hemicelluloses and lignin, and if necessary consider ways of isolating the individual reaction products so that they can be processed separately. Hydrolysis has proved to be a most effective method of opening up the wood structure for subsequent treatments. The expression hydrolysis of wood is used rather loosely. It is not technically correct since the reactions affect primarily the carbohydrate fraction of wood. Lignin is largely unaffected. 

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