Dixon procedure

Dixon procedure. This method (Dixon, 1953) allows the detennination of the constant Ki for an inhibition (competitive or not). One plots the reciprocal of the velocity against the inhibition concentration, at two fixed substrate concentrations ([S]2>[S]i). 

Prieur, D.J., Young, D.M., Davis, R.D., Cooney, D.A., Homan, E.R., Dixon, R.L. and Guarino, A.M. (1973). Procedures for preclinical toxicologic evaluation of cancer chemotherapeutic agents Protocols of the laboratory of toxicology. Cancer Chemotherapy Reports, Part 3, 4 1-30. 

Dixon [75] also investigated the use of unconventional carbon donors, such as the mandelic acid derivative 119 in the highly stereoselective addition to -substituted nitro-olefms. The Michael product 120 was formed smoothly and can be converted in simple one-step procedures to generate various chiral building blocks for syntheses (Scheme 26). 

If the data as a whole appear normally distributed but there is concern that an extreme point is an outlier, it is not necessary to apply the Rankit procedure. The Grubbs s outlier test (1950) is now recommended for testing single outliers, replacing Dixon s Q-test. After identifying a single outlier, which, of course, must be either the maximum or minimum data value, the G statistic is calculated ... 

To assess the validity of this procedure, a series of coal ashes analyzed by the British Coal Utilization Research Association (BCURA) were again analyzed with the two types of ash prepared in our laboratories. Calibrations for these analyses were prepared from U. S. Geological Survey and National Bureau of Standards rock standards, IB, Gl, Wl, and Nos. 78, 79, 88. The values determined for the BCURA coal ashes agreed excellently with results obtained at BCURA by Dixon et al. (3). Standard deviations were calculated for the duplicate coal ash determinations Si 0.07%, Ti—0.01%, Al—0.06%, Fe—0.05%, Mg—0.02%, Ca—0.03%, K—0.01%, P—0.01%, and V—1.3 ppm. These deviations are comparable with Class A wet silicate analyses and indicate a high degree of precision. 

Recently, R. Fields, H. B. F. Dixon, and C. Yui (unpublished) have developed a chromatographic system for the isolation of RNase Tj. This procedure uses only a column of DEAE-cellulose equilibrated with a buffer of 0.08 M NaH2P04 and 0.12 M Na2HP04 after the water extraction of Takadiastase Y powder. 

Various experimental procedures were described as models for glomerulonephritis in human beings. Most of them were developed in rats and rabbits. They involve the reactions of antibodies against renal components, such as Masugi nephritis (Masugi and Sato 1934), Heymann nephritis (Heymann 1959), nephrotoxic serum nephritis (Unanue and Dixon 1967), crescentic type anti-glomerular membrane nephritis (Nagoe et al. 1994, 1998), anti-Thyl nephritis (Chen etal. 1999). 

Bartuska VJ, Maciel GE, Bolkers HI, Fleming Bl (1980) Structural studies of lignin isolation procedures by nC NMR Holzforschung 34 214-217 Dixon WT, Schaefer J, Sefcik MD, Stejskal EO, McKay RA (1981) Quantitative chemical composition of materials such as humic soils, lignins, and coals by high-resolution carbon 13 NMR J Magn Reson 45 173-176... 

P. C. Andrews and J. E. Dixon, A procedure for in situ alkylation of cysteine residue on glass fiber prior to protein microsequence analysis, A aZ. Biochem. 161 (1987), 524-528. 

Applying the first method, four different criteria, namely Dixon s test, Grubbs test, the coefficient of dewness test and the coefficient of kurtosis test are used at a significance level of a = 0.05. If a laboratory mean for each element as single unweighted value was declared to be an outlier by any criterion, it is rejected and the whole procedure repeated until no more outliers could be identified. The remaining laboratory means are then combined in the usual way to provide estimates of the overall mean (consensus value) and its associated standard deviation, standard error and 95% confidence interval. 

A further study of these second-order effects has been made by Dingle and Dixon (133) who had earlier found that the F NMR spectrum of [PtF(PPh3)3] could not be interpreted using a simple first-order analysis procedure (134). Their conclusions on the hydro. complexes (133) were essentially the same as those proposed earlier (279) however, they extended the study to cations [PtH(PEt3)3]and... 

Studying chemical modification will be described. Histones are modified in vivo by acetylation (also methylation and phosphorylation, see DeLange and Smith 1971, 1974). In some histones the a-amino groups are acetylated (in addition to lysine residues) and this precludes direct examination of the internal sites of acetylation by the Edman procedure. However, histones IIb2 and III have free a-amino groups and this enabled Candido and Dixon (1972) to examine these histones (from trout testis) which had been acetylated intracellularly with " C-labeled acetate. Each residue that was released by the Edman procedure (using a sequenator) was examined for radioactive material and it was found that lysyl Residues 14 and 23 (major sites) and 9 and 18 (minor sites) were partially acetylated in histone III and lysyl Residues 5,10,13 and 18 were partially acetylated in histone IIb2. This type of approach should be applicable to many other studies of chemical modification. 

The molecular representation is the way that a molecule, that is, a phenomenological real body, is symbolically represented by a specific formal procedure and conventional rules. The quantity of chemical information, which is transferred to the molecule symbolic representation, depends on the kind of representation [Testa and Kier, 1991 Jurs, Dixon et al, 1995]. 

The manometric procedure for measuring oxygen consumption, first introduced by Warburg is still the most accurate method when utilized under appropriately chosen conditions (Dixon, 1943 Umbreit et al., 1964 Slater, 1967). The serious limitations in manometric techniques are the difficulty in following rapid changes in the gas phase and the relatively long time necessary for both equilibration and measurement. 

Kuhn, with his column, reached a concentration of 6 at. % of 0. Dostrovsky and his collaborators at the Weiszmann Institute in Israel [53], prepared of about 95% purity and of about 2%. The preliminary concentration from 0.2 to 1.6% of 0 was carried out in 10 columns connected in parallel (diam. 100 mm). The multistage cascade (diam. 80—100 mm) was fed at 800 ml/h and was operated with a takeoff ratio of 1.37 X10. The procedure is to be improved so as to produce a concentration of 99.8%. The highest concentration of is present at the centre of the cascade (<%i 10%). In these separations the Dixon packing, made of 100 mesh phosphor bronze wire gauze in the shape of a Raschig ring with an S-shaped bridge, proved its value... 

Dixon M, Webb EC (1979) Enzymes, 3rd edn. Academic Press, New York, 1116 pp Eisenthal R, Cornish-Bowden A (1974) The direct linear plot. A new graphical procedure for estimating enzyme kinetic parameters. Biochem J 139(3) 715-720 Ertan H, Kazan D, Erarslan (1997) Cross-hnked stabilization of Escherichia coli penicilhn G acy-lase against pH by dextran-dialdedhyde polymers. Biotechnol Tech 11 225-229 Ferreira JS, Straathof AJJ, Franco TT et al. (2004) Activity and stability of immobilized penicillin acylase at low pH values. J Mol Catal B Enzym 27 29-35 Guranda DT, Volovik TS, Svedas VK (2004) pH stability of penicillin acylase from Escherichia coli. Biochemistry (Moscow) 69(12) 1700-1705... 

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