Acid-soluble fractions

Historical. Pyridines were first isolated by destructive distillation of animal bones in the mid-nineteenth century (2). A more plentifiil source was found in coal tar, the condensate from coking ovens, which served the steel industry. Coal tar contains roughly 0.01% pyridine bases by weight. Although present in minute quantities, any basic organics can be easily extracted as an acid-soluble fraction in water and separated from the acid-insoluble tar. The acidic, aqueous phase can then be neutrali2ed with base to Hberate the pyridines, and distilled into separate compounds. Only a small percentage of worldwide production of pyridine bases can be accounted for by isolation from coal tar. Almost all pyridine bases are made by synthesis. 

These three compounds exert many similar effects in nucleotide metabolism of chicks and rats [167]. They cause an increase of the liver RNA content and of the nucleotide content of the acid-soluble fraction in chicks [168], as well as an increase in rate of turnover of these polynucleotide structures [169,170]. Further experiments in chicks indicate that orotic acid, vitamin B12 and methionine exert a certain action on the activity of liver deoxyribonuclease, but have no effect on ribonuclease. Their effect is believed to be on the biosynthetic process rather than on catabolism [171]. Both orotic acid and vitamin Bu increase the levels of dihydrofolate reductase (EC 1.5.1.4), formyltetrahydrofolate synthetase and serine hydroxymethyl transferase in the chicken liver when added in diet. It is believed that orotic acid may act directly on the enzymes involved in the synthesis and interconversion of one-carbon folic acid derivatives [172]. The protein incorporation of serine, but not of leucine or methionine, is increased in the presence of either orotic acid or vitamin B12 [173]. In addition, these two compounds also exert a similar effect on the increased formate incorporation into the RNA of liver cell fractions in chicks [174—176]. It is therefore postulated that there may be a common role of orotic acid and vitamin Bj2 at the level of the transcription process in m-RNA biosynthesis [174—176]. 

TRAP, Total peroxyl-radical-trapping antioxidant capability of plasma TEAC, Trolox equivalent antioxidant capacity FRAP, ferric-reducing activity of plasma ORAC, oxygen-radical-absorbing capacity PCA, perchloric acid-soluble fraction ABAP, 2,2 -azobis(2-amidoproane). 

Hyperoxia (48-hr exposure to >99% 02) decreased TAC of rat lung homogenates (cytosol fraction) by 26%. TAC of the acid-soluble fraction was even more depressed (by 40%). Feeding rats before the experiment with vitamin E-rich diet (500 IU/kg of vitamin E acetate) or diet containing blueberry extract (2.5%) but not spinach extract (0.85%) attenuated this effect of hyperoxic exposure (C14). 

Although most workers have used the same extractant, 5 % TCA (or occasionally 0.5 M HCIO4), to obtain the acid-soluble fraction, a variety of methods have been used to isolate acid-insoluble condensed phosphates. The most common method of extraction of acid-insoluble PolyPs from cells involves the use of dilute sodium hydroxide solution, pH 9-12 (MacFarlane, 1936 Belozersky, 1955 Belozersky and Kulaev, 1957 Mudd et al., 1958 Krasheninnikov et al., 1968). Widely used methods for the extraction of acid-insoluble PolyPs from biological materials are several variants of the method of Schmidt and Thannhauser, i.e. the use of 1 M potassium hydroxide at 37 °C for various periods of time (Schmidt and Thannhauser, 1945 Chaloupka and Babicky, 1957,1958 Zaitseva etal., 1959 Griffin et al., 1965 Griffin and Penniall, 1966). 

The acid-soluble fraction, PolyP , was extracted with 0.5 M HCIO4 (or 10 % tri-choroacetic acid) at 0 °C for 30 min. The salt-soluble fraction, PolyP(II), was extracted with a saturated solution of NaC104 at 0 °C for 1 h. The weak alkali-soluble fraction, PolyP(III), was extracted with weak NaOH, pH 9-10, at 0 °C for 30 min. The alkali-soluble fraction, PolyP(IV), was extracted with 0.05 M NaOH at 0 °C for 30 min. The last fraction, PolyP(V), was assayed by the amount of Pi which appeared after the hydrolysis of biomass in 0.5 M HCIO4 at 90 °C for 40 min. 

While PolyPs are localized in different compartments of the yeast cell, it is important to determine the effects of P starvation and P, overplus on PolyPs in organelles. The content of PolyP in vacuoles of the yeast S. cerevisiae was 15 % of the total cellular PolyP. Over 80 % of vacuolar PolyPs were represented by the acid-soluble fraction. It was established by 31P NMR spectroscopic studies that the polymeric degrees ( ) of two subfractions obtained by precipitation with Ba2+ ions in succession at pH 4.5 and 8.2 were approximately 20 5 and 5 2 residues of orthophosphoric acid, respectively. Under the deficit of phosphate (P ) in the culture medium, the PolyP content in vacuoles decreased sevenfold at the same drastic reduction of its content in the cell. Unlike the intact yeast cells where PolyP overcompensation is observed after their transfer from phosphate-free to phosphate-containing medium, the vacuoles do not show this effect (Table 8.2). The data obtained indicate the occurrence of special regulatory mechanisms of PolyP synthesis in vacuoles differing from those in the whole cell. 

Mitochondria possess a PolyP pool, which is strongly influenced by the P content in the medium (Pestov et al, 2003). Table 8.3 shows that the PolyP content in mitochondria increases sufficiently under phosphate overplus. This PolyP, represented by the acid-soluble fraction, had a chain length of 25, estimated by electrophoresis under phosphate overplus (Pestov et al., 2003) and was shorter ( 15) under the control conditions. 

Inhibitions of cell wall biosynthesis can be determined independently from DNA, RNA and protein biosyntheses. They will usually have been signaled by bactericidal effects and lysis of the test culture. In many instances, inhibition of cell wall synthesis results in the progressive accumulation of intermediates which can be assayed colorimetrically64, 6J) for N-acylaminohexose in acid-soluble fractions of the test bacteria. 

The results of incorporation experiments using tritiated thymidine lend support to the hypothesis that thymidine rhamnosyl pyrophosphate in Lactobacillus acidophilus is an intermediate on the pathway to deoxyribonucleic acid synthesis. When cells were grown in a medium containing tritiated thymidine, labeled thymidine rhamnosyl pyrophosphate constituted two-thirds of the total label in the acid-soluble fraction. When these cells were transferred to a medium containing 2-deoxyadenosine, 2-deoxy-guanosine, and 2-deoxycytidine as the nucleosides, 99 % of the label initially present was transferred to deoxyribonucleic acid after incubation for 50 minutes. Therefore, almost complete incorporation (into deoxyribonucleic acids) of the isotope from tritiated th3anidine had occurred. 

Diaminopurine was also incorporated into the acid-soluble fraction of Streptococcus faecalis and Lactobacillus coset. None of these organisms, however, synthesized 6-amino-2-methylaminopurine in amounts detectable on chromatograms. 

Azauracil [1,2,4-triazine-3,5(2,4)-dione] inhibits the growth of various micro-organisms. When grown in the presence of 6-azauracil- -C, Streptococcus jaecalis accumulates radioactive metabolites in the acid-soluble fraction of the cells. A major metabolite is D-ribofuranosyl-6-aza-uracil. This material is identical with material prepared by condensing tri-O-benzoyl-D-ribofuranosyl chloride with the mercuric derivative of 6-azauracil, followed by debenzoylation. A second major metaboUte was tentatively shown to be D-ribosyl-6-azauracil 5-phosphate. Bacteria develop resistance against 6-azauracil and its D-ribosyl derivative. Resistant Streptococcus faecalis will not convert 6-azauracil to its D-ribosyl derivative or to other bound forms, and the bacterium has also lost the ability to incorporate uracil into the nucleic acids of its cells. 

A comprehensive analysis has been made of the nucleotides in the acid-soluble fraction of Escherichia coli strain B before and after infection with... 

T2r bacteriophage. The molar proportions of the bases in the acid-soluble fraction of normal Escherichia coli strain B, relative to adenine, were as follows adenine, 1.0 guanine, 0.99 cytosine, 0.09 uracil, 0.95 and thymine, 0.09. The figures for the infected system are in sharp contrast to those of the normal system adenine, 1.0 guanine, 0.11 cytosine, 0.08 lu-acil, 0.38 and thymine, 0.54. 

The infected system was shown to contain deoxymidine 5-phosphate this observation is interesting, since this nucleotide has not yet been shown to be present in normal cells. The nucleotide is presumably used for the synthesis of thymidine 5-triphosphoric acid. Detectable quantities of 5-(hydroxymethyl)cytosine or of 5-(hydroxymethyl)cytosine nucleotides were not present, despite the fact that this base is a normal constituent of the phage deoxyribonucleic acid. Explanations for this observation are that (a) the amount present in the acid-soluble fraction at any given moment is too small for detection by the methods of anal3rsis employed, or (b) the newly synthesized 5-(hydroxymethyl)cytosine is directly incorporated into deoxyribonucleic acid. 

Step 1. Extraction of the acid soluble fraction (i.e., carbonates) with CH3COOH Step 2. Extraction of the reducible fraction (i.e., iron/manganese oxides) with hydroxyl amine hydrochloride... 

Metal contamination of soils is primarily due to the application of sewage sludge, manure, phosphate fertilizers, atmospheric deposition, and traffic emissions. The most common heavy metal ions found in soils are Zn, Cu, Ni, Pb, Cr, and Cd. As mentioned earlier (see Section 6.3.1.4), sequential extraction techniques can differentiate among the metal forms in a soil, typically the acid soluble fraction (e.g., carbonates), the reducible fraction (e.g., iron/manganese oxides), and the ox-idizable fraction (i.e., metals in low oxidation states). 

Various chemical extraction techniques have been introduced in order to selectively remove metals from the different adsorption or complexation sites of natural sediments (e.g., Tessier et al, 1979 Erel et al, 1990 Leleyter et al., 1999). It is, for example, shown by Leleyter et al. (1999) that between 20% and 60% of REE in various suspended river sediments are removed by successive extractions by water, by Mg(N03)2 (exchangeable fraction), sodium actetate (acid-soluble fraction), NH2OH - - HCl (manganese oxide dissolution) ammonium oxalate (iron oxide dissolution) and a mixture of H2O2 + HNO3 (oxidizable fraction). The complexity of... 

The fulvic acid fraction has a straw-yellow color at low pH values and turns to wine-red at high pH values, passing through an orange color at a pH near 3.0. There is little doubt that compounds of a nonhumic nature are present. The term fulvic acid should be reserved as a class name for the pigmented components of the acid-soluble fraction. 

Mineralization of the organic matter begins by transformation of the a-amino groups into ammonia. This conversion is observed in the acid-soluble fraction obtained when carbonates are removed by acid treatment of the sediment prior to alkaline extraction. In this fraction, the ratio of ammonium nitrogen to a-amino nitrogen increases steadily with burial in the first few meters of the sediment (Jocteur-Monrozier and Jeanson, 1981). However, these data are not always easy to interpret due to the dissolution, diffusion, and adsorption of ammonium nitrogen on clay minerals. 

The experimental evidence obtained indicates that the thr key constituents may be segregated within the tungsten ore tailings whose acid-soluble fraction consists of three major phases ... 

A synthetic phaeomelanin can be easily obtained by the tyrosinase-catalyzed oxidation of L-tyrosine or L-dopa in the presence of excess L-cysteine at pH 6.8 followed by chromatography of the acid-soluble fraction on a Sephadex column. This procedure leads to the isolation of four major reddish brown pigments that are similar to natural... 

Nonbuffered acetic acid solutions (0.1 to 1.0 mol L ) are frequently used to strip the specifically adsorbed fraction. A 0.11 mol L acetic acid solution is used in both the original and modified SM T procedures for the simultaneous extraction of water-soluble, exchangeable, and acid-soluble fractions (Ure et al., 1993 Rauret et al., 1999). The higher the concentration of acetic acid, the higher was the recovery of TEs. For a set of contaminated soils and sediments, the 0.43... 

Step 1. Metals extracted during this step are those which are exchangeable and in the acid-soluble fraction. These includes weakly absorbed metals retained on the sediment surface by relatively weak electrostatic interaction, metals that can be released by ion-exchange processes and metals that can be coprecipitated with the carbonates present in many sediments. Changes in the ionic composition, influencing adsorption-desorption reactions, or lowering of pH, could cause mobilization of metals from such fractions. 

It was established that the acid soluble fraction constituted 39% of the total galacturonides, 59% of total arabinose and 31% of total rhamnose. By ion-exchange chromatography it was shown that the... 

Separation of a mixture of secondary and tertiary amines is best accomplished by acetylation followed by trituration with dilute mineral acids. The acid soluble fraction contains the tertiary amine. The secondary amine may be regenerated from its insoluble acetyl derivative by mild acid hydrolysis. Benzoylation, however, cannot be applied with equal impunity for under the conditions for this reaction certain isoquinoline alkaloids (aporphines) suffer ring fission and benzoylation at the nitrogen atom. 

Neutralising value is an analytical term for that proportion of limestone, quicklime, or hydrated lime (expressed as CaO) that is capable of reacting with hydrochloric acid under specified conditions. It includes the contribution of CaCOs, CaO, Ca(OH)2, and the acid-soluble fraction of the calcium silicates, aluminates and ferrate. 

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