Potassium phosphate buffer

D-Methyl mannoside with 2 M KSCN at pH 7.5 in potassium phosphate buffer... 

The ionic species of the mobile phase will also affect the separation. This is shown in Table 4.3 by the difference in resolution values for magnesium chloride buffer compared to sodium sulfate buffer. In addition, calibration curves for proteins in potassium phosphate buffers are shallower than those generated in sodium phosphate buffers. The slope of the curve in Sorenson buffer (containing both Na and ) is midway between the slopes generated with either cation alone (1). Table 4.4 illustrates the impact of different buffer conditions on mass recovery for six sample proteins. In this case, the mass recovery of proteins (1,4) is higher with sodium or potassium phosphate buffers (pH 6.9) than with Tris-HCl buffers (pH 7.8). 

An amount of enzyme preparation equivalent to 900 mg of wet cells was made up to 25 ml with the above potassium phosphate buffer solution. 150 mg (1.15 mmol) of 5-fluorouracil and 1.0 gram of thymidine (4.12 mmol) were dissolved in 15 ml of the above potassium phosphate buffer solution. The mixture was incubated at 37°C for 18 hours. After this time, enzyme action was stopped by the addition of four volumes of acetone and one volume of peroxide-free diethyl ether. The precipitated solids were removed by filtration, and the filtrate was evaporated under nitrogen at reduced pressure until substantially all volatile organic solvent had been removed. About 20 ml of aqueous solution, essentially free of organic solvent, remained. This solution was diluted to 100 ml with distilled water. 

Figure 3 Reversed-phase chromatography of products after alkaline hydrolysis of /3-poly(L-malate), Discrete polymer products are formed, which differ in length by several units of L-malate. The absorbance at 220-nm wavelength was measured, (a) /3-Poly(L-malate) before hydrolysis, (b) After 10-min incubation in 20 mM NaOH at 37°C. (c) After 15 h in 20 mM NaOH at 37°C. (d) After I h in 500 mM NaOH at 100°C. High pressure chromatography (HPLC) on Waters reversed-phase Ci8- i-Bondapak. The methanol gradient (in water-trifluoro acetic acid, pH 3.0) was programmed as follows 0-40 min 0.3-23%, 40-47 min 23-40%, 47-49 min 40%, 49-54 min 40-0%. (d) Inset size exclusion chromatography after 3-min alkaline hydrolysis at pH 10.2. BioSil SEC 250 column of 300 mm x 7.8 mm size, 0.2 M potassium phosphate buffer pH 7.0.

Fig. 7.3.4 Kinetic profiles of the Diplocardia bioluminescence reaction, when Diplocardia luciferase, H2O2, or Diplocardia luciferin was injected last. In each case, 0.1 ml of the last component was injected into 0.9 ml of the mixture of other components, to give the final concentrations Diplocardia luciferase, 0.1 unit/ml Diplocardia luciferin, 32 mM and H2O2, 32 mM, in 0.1 M potassium phosphate buffer, pH 7.5. From Rudie et al., 1981, with permission from the American Chemical Society.

Preparation of luciferase. Organisms were freeze-dried, powdered, and washed with ethyl acetate to destroy the majority of catalase activity. The washed residue was extracted with 50 mM potassium phosphate buffer, pH 6. The extract was fractionated by ammonium... 

Preparation of Balanoglossus luciferin. The residue of the first pH 6 extraction above was re-extracted with 50 mM potassium phosphate buffer, pH 8. After centrifugation, the supernatant was used as the standard luciferin preparation. Luciferin was highly labile and easily inactivated at an extreme pH, by heat, and also by freezing and thawing. The instability resembled that of certain proteins. 

In the Phadebas TM amylase test (72) (Pharmacia Labs) the substrate was a water insoluble cross-TTnked blue starch in tablet form which also contains some inert ingredients, sodium and potassium phosphate buffer salts and sodium chloride. This polymer was hydrolyzed by amylase into water soluble blue starch fragments. After centrifugation the absorbance of the blue supernatant was proportional to the activity of amylase present in the test samples. The day to day variation on a quality control serum had a coefficient of variation of 2.7% based on 30 days of data in our laboratory. The method is simple, reproducible and uses microquantities of serum. 

Dihydroxybenzoate decarboxylase activity of these bacteria was induced specifically by 2,6-dihydroxybenzoate. The enzyme activity in a cell-free extract of A. tumefaciens 1AM 12048 was stable during storage at 4°C for 7 days in potassium phosphate buffer (pH 7.0) containing 1 mM dithiothreitol. Different from 4-hydroxybenzoate decarboxylase and 3,4-dihydroxybenzoate decarboxylase, 2,6-dihydroxybenzoate decarboxylase was much less labile and barely... 

The carboxylafion of indole into indole-3-carboxylate was observed by the purified indole-3-carboxylate decarboxylase as well as by the whole cells. For the carboxylafion reaction, temperatures over 30°C were not appropriate. The activities at 10, 20, and 30°C were about the same. The activity was maximal at pH 8.0 (Tris-HCl buffer, 100 mM). As shown in Fig. 10, the resting cells of A. nicotianae F11612 also catalyzed the carboxylafion of indole efficiently in the reaction mixture containing 20 mM indole, 3M KHCO3, 100mM potassium phosphate buffer (pH 6.0) in a tightly closed reaction vessel. By 6h, 6.81 mM indole-3-carboxylic acid accumulated in the reaction mixture with a molar conversion yield of 34%. Compared to the carhoxylation of pyrrole by pyrrole-2-carboxylate decarboxylase, the lower value compared might derive from the lower solubility of indole in the reaction mixture. 

Figure 4.16 A model for the surface of silica gel in equilibrium with a mobile phase of (55 40 5 methanol-water-0.2 M potassium phosphate buffer (pH 7.5) with the addition ot 2.5 aM of cetyltrimethylammonium bromide. (Reproduced with permission from ref. 279. Copyright pergamon Journals Ltd).

Figure 15.3 (a) Heat absorption in solutions of native RNase A (trace 1) and RNase A kept in 10% buffered formalin for 2 days (trace 2) and 6 days (trace 3) at pH 7.4 and 23°C. All samples were dialyzed against 75 mM potassium phosphate buffer (pH 7.4) prior to DSC. (b) Dependence of Td of the dialyzed RNase A samples on time of incubation in 10% buffered formalin at pH 7.4 and 23°C. (c) Heat absorption of solutions of formalin-treated RNase A fractions isolated by size-exclusion gel chromatography monomer (trace 1), dimmer (trace 2), and a mixture of oligomers with >5 cross-linked proteins (trace 3). Protein concentrations were 0.5 mg/mL. The thermal denaturation transition temperature (Td) is defined as the temperature of the maximum in the excess heat absorption trace associated with the protein s endothermic denaturation transition. See Rait et al.10 for details. 

Procedure The Ascorbate peroxidase (EC 1.11.1.7) activity can be obtained by measuring the oxidation of ascorbate in the presence of H202. Grind the algal sample in liquid nitrogen and extract in 2.5 ml 50 mM potassium phosphate buffer (pH 7.0) containing 10% (w/v)... 

Bring the reduced cytochrome c solution to a final volume of 4.5 mL with 50 mM potassium phosphate buffer. 

Elute with 200 mL buffer supplemented with a linear gradient of 0.0 to 0.35 MpH 7.7 potassium phosphate buffer. 

Fig. 44. Single crystal-like I4N-ENDOR spectrum of metmyoglobin with B0 along gli temperature 2.1 K (Mb chromatog-raphically purified, 6 nM in 50% (v/v) glycerol, 0.1 M potassium phosphate buffer, pH = 6.0). (Adapted from Ref. 241)...

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