Stable fraction

In a recent placebo-controlled study, 2 month s vitamin E treatment in patients with type 1 diabetes resulted in a significant dose-dependent fall in glycosylated proteins independent of changes in plasma glucose (Ceriello et al., 1991). Dose-related falls in both labile and stable fractions of haemoglobin Al also occurred. 

The partition index (IR, which will be discussed in details below) of Cd, Cu, Cr, Ni and Zn in both soils rapidly increased from time zero (calculated value) to one day and further to one year. This was especially true for Cr, Cu and to some extent Ni and Cd (Table 6.5). This result indicates that added trace metals are initially and rapidly transferred from the labile EXC fraction into the more stable fractions. Furthermore, IR of trace metals in native arid soils incubated under the saturated paste regime decreased at the end of year. This indicates mobilization of trace elements in these soils as saturation (Table 6.5). Also, it can be seen that IR decreased, for any given time, with an increase of the loading level (Table 6.5, Fig. 6.5). This means that higher additions of soluble metals result in higher metal content in the labile fractions and lower metal binding intensity in soils. 

The hepatic endoplasmic reticulum possesses oxidative enzymes called mixed-function oxidases or monooxygenase with a specific requirement for both molecular oxygen and a reduced concentration of nicotinamide adenine dinucleotide phosphate (NADPH). Essential in the mixed-function oxidase system is P-450 (Figure 1.12). The primary electron donor is NADPH, whereas the electron transfer involved P-450, a flavoprotein. The presence of a heat-stable fraction is necessary for the operation of the system. 

Adani, F., Ricca, G.,Tambone, F., and Genevini, P. (2006). Isolation of the stable fraction (the core) of the humic acid. Chemosphere 62,1300-1307. 

Since black C has a highly aromatic structure with a low level of substitution with functional groups, it is highly recalcitrant and therefore contributes to the stable fraction of soil C. At the global scale, formation of black C rapidly transfers fast-cyclable C from the biosphere to much slower-cyclable forms that may persist in the soil for millennia. It therefore represents an effective pathway for C sequestration. 

Conventional tillage exposes the OM, which are naturally stabilized in the soil, to the action of sunlight and oxidation conditions that favor microbial activity. Consequently, only the very stable fraction of SOM generally remains. The importance of SOM functions is well known, but structural information, chemical composition, and changes induced by anthropogenic factors, such as tillage practices, are still under research. 

Formation of alkaline stable fraction was observed a long time ago and it was assumed, but not proven, that it is composed of cyclic macromolecules [145]. The alkaline stable fraction could be either cyclic or terminated at both ends with—OCH3 groups. CH30—end groups are indeed formed in this system, due to hydride transfer reaction to carboxonium ion ... 

Figure 1 GPC curves of polyoxymethylene (a) obtained by bulk polymerization of 1,3,5-trioxane at 70° C with BF3OBU2 as initiator, Mw = 55,600 (b) its alkaline-stable fraction.

Table 11 Polymerization Conditions, Amounts of Alkaline-Stable Fraction, and Low Molecular Weight Fraction in the Cationic Polymerization of 1,3,5-Trioxane...

Catlyst (-10 6 mol) Time (min) Conversion (%) Alkaline-Stable Fraction,% Fraction Low Molecular GPC Peak,%... 

Cellular receptors for activated or cell-bound components. The fact that both heat-labile and heat-stable fractions of... 

It would appear likely that a sex difference possibly exists in alkaline phosphatase among individuals lacking the slow intestinal bands. Female subjects exhibit an appreciably lower ratio of the heat-stable fractions for non-LPSAP and LPSAP. 

The fact that the total number of theoretically possible protein structures that an individual amino acid chain of 150 residues might adopt - assuming that each peptide group has only three conformations - is 3 or 10 (Brandon and Tooze, 1999) whereas the total number of permissible folds is of the order of 1000 graphically illustrates just how restrictive the laws of protein-fold form are. Whatever the actual figure, the total number of folds is bound to represent a tiny stable fraction of all possible polypeptide conformations, determined by the laws of physics. This further reinforces the notion that the folds, like atoms, represent a finite set... 

When starch is treated with hot alkaline solutions, it behaves in the manner to be expected of a material composed of an alkali-labile fraction and an alkali-stable fraction. Starches from different sources vary in the relative amounts of these two components, and, therefore, starches can be characterized by their alkali lability. Alkali lability of a starch can be expressed as its alkali number, which is an empirical expression of the acids produced from the terminal, reducing group by the action of alkali. The alkali number (and, therefore, the alkali lability) increases progressively during acid hydrolysis. - Hence, the alkali number is an index of molecular size for linear molecules. 

Amylopectin, the so-called alkali-stable fraction of starch, undergoes very... 

Early studies by Overath and Stumpf (P. Overath, 1964) established not only that the constituents of the avocado fatty acid synthesis system could be dissociated and reconstituted, but also that the heat stable fraction from E. coli known as acyl carrier protein (ACP) could replace the corresponding fraction from avocado. Plant ACPs share both extensive sequence homology and significant elements of three-dimensional structure with their bacterial counterparts. In plants, this small, acidic protein not only holds the growing acyl chain during fatty acid synthesis, but also is required for synthesis of monounsaturated fatty acids and plastidial glycerolipids. 

The stable OCH3 end-groups, that are formed in this process, may be responsible for the observation that the polyoxymethylene contains up to 25 % of a thermally stable fraction 48). One has to remember, however, that thermal stability may at least partially be due to the inevitable presence of macrocyclics 101>. 

Table 7.16. Dependence of the content of the stable fraction" in the l,3,5-Trioxane-l,3-Dioxolane copolymers6 on the proportion of 1,3-Dioxolane units and the degree of polymerization 137)...

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