Of borate buffer

Cox et al. (1981) found, as expected, that the trianion of 2,3-dihydroxynaph-thalene-6-sulfonic acid has a higher reactivity than the dianion. They observed a specific catalytic effect of borate buffers, but unfortunately they did not investigate it further. 

Homogenize 50 g of a prepared sample with a solution containing 50 mL of borate buffer (pH 10) and 50 mL of acetone in a blender for 5 min. Pour the homogenate into an Erlenmeyer flask, add 50 mL of acetone and shake the flask for 10 min using a shaker. Filter the aqueous acetone extract through a 25G-4 glass filter overlaid with 3 g of Celite. Wash the residue on the filter with 50 mL of acetone. Combine the filtrates and remove acetone by rotary evaporation. Transfer the residue with 5 mL of 4% sodium dodecyl sulfate aqueous solution into a separatory funnel, extract the solution with two portions of 50 mL of dichloromethane and collect the organic... 

The sample was mixed with an equal volume of borate buffer (pH 9.2). Titration with 0.01 M EDTA gave two breaks corresponding to the concentration of each cation. 

Mochizuki et al. also demonstrated that the uncatalyzed autoxidation of catechins is suppressed in the presence of a sufficient amount of borate buffer (44). This was interpreted by considering the adduct formation between borate ion and the catechins. The oxidation resumes on addition of Cu(II) in the presence of the borate ions. This may indicate that Cu(II) forms more stable complex(es) with the catechins than the borate ion, but direct oxidation of the catechin-borate complex by Cu(II) cannot be excluded either. 

A practical, inexpensive one-step procedure was developed for the RhaD-catalyzed gram-scale synthesis of L-fructose. The requirement for DHAP as the donor substrate was circumvented by use of borate buffer, presumably by in situ formation of borate esters as a phosphate ester mimic. Racemic glyceraldehyde was also used, as the enzyme preferentially accepted the L-enantiomer as a substrate. The method can also be apphed to other products, including L-rhamnulose, and towards a two-step synthesis of L-iminocychtols. ... 

Borate buffer treatment (pH 8.3), vortexmixing, centrifugation, pellet dissolved in 6M urea and dithiodu eitol Tryptic digestion of borate buffer precipitate Centrifugation at 5000rpm (for skimming), filtration, dilution... 

In a detailed study of the original methods,236 it was observed that the presence of borate buffer increases the intensity of the color in the reaction, thus permitting the development of a more sensitive analytical method.237... 

In both MEKC methods reported, the mobile phase consisted of borate buffer containing surfactant and acetonitrile. It was foimd that mobile phase prepared at pH 9.75 gave better resolution compared to other conditions, and increasing pH also increased the migration time of ezetimibe. An analyte concentration of 25 mM was chosen due to its lower current, and the sharp peaks observed [41]. In addition, for the analysis of ezetimibe in combination with another drug such as simvastatin, increasing the borate concentration increased both resolution and migration times. 

Tiollais et al. (1972) add 0.2% SDS to all solutions to inhibit nuclease activity. The 10 x concentrated stock solution of borate buffer (Peacock and Dingman 1968) contains per litre 108 g Tris base 9.3 g EDTA (Na salt) 55 g boric acid and 20 g SDS if required. This gives a pH of 8.3. It should be noted that sodium SDS is not soluble below about 15°C. The Li salt is soluble at 0°C. 

The most suitable use of borate buffers will be in the separations of mixtures of isomeric polyhydroxy acids. The behavior of phosphate, triose phosphate, and hexose phosphate under a variety of conditions in nonborate buffers was examined by Neil and Walker, who found that the... 

Immobilized trypsin-agarose was prepared as reported elsewhere (6). Trypsin immobilization was carried out in presence of borate buffer (50 mM) containing benzamidine (75 mM) at pH 10 and 25°C. After 72 hours, the trypsin-agarose was reduced with NaBH4 (Img/ml) for 30 minutes. Finally, the immobilized preparation was washed with water and stored at 4 C. The derivative obtained had around 320 units/ml gel using benzoyl-arginine ethyl ester (BAEE) as substrate. One unit of enzyme activity is defined as... 

Store the solutions at 0-5°C. Warm 1 mL of each solution to about 25°C over 15 min and use 50 xL of each solution for each titration. Carry out the titration in an atmosphere of nitrogen. Transfer 10.0 mL of borate buffer solution pH 8.0 (0.0015 M) R to the reaction vessel and, while stirring, add 1.0 mL, of a freshly prepared 0.686% m/V solution of benzoylarginine ethyl ester hydrochloride R. 

The separations at extremely high pH can only be performed in bare fused-silica capillaries, since most coatings undergo hydrolytic degradation under the highly basic conditions. The use of electrolyte systems containing alkaline-earth metals for the separation of neutral carbohydrates by CZE is mainly based on differences in the extent of complexation of the divalent metals with the carbohydrate solutes, as well as the size and shape of the molecule. These systems provided a different selectivity from that of borate buffers, although the resolution is often inferior. 

Sugai et al. [166] suggest that chemically modified cellulase in the presence of borate buffer might be useful for biopolishing of cellulosic fibers. They found that the decline in the breaking strength of ramie yarns was improved, when the modified enzyme was used. 

Samples were deproteinized with 0.2 M HC104- Before reaction with 0PA-thiol, a known amount of 3-3 -diaminodipropylamine was added to the tissue homogenates as an internal standard and perchloric acid extracts were adjusted to pH 9.5 by addition of borate buffer. For quantitation, polyamines were compared to the internal standard. The peak height ratios of polyamine to internal standard for a known concentration of polyamine was presented in Table 1. 

Add 100 mg of sulfosuccinimidyl 6-(biotinamido) hexanoate and 30 mg of tyramine-HCl to 40 ml of borate buffer, then stir gently overnight. 

Schmitt-Kopplin P, Hertkom N, Garrison AW, Freitag D, Kettup A (1998) Influence of borate buffers on the electrophoretic behavior of humic substances in capillary zone electrophoresis. Anal Chem 70 3798-3808. doi 10.1021/ac971223j... 

Add 0.1 mL of borate buffer and 0.01 mL of reagent to 1 mL of unfiltered seawater sample in a pre-cleaned conical reaction vial (capacity ca. 2mL). Mix thoroughly and allow the mixture to react for exactly 10 min. Liebezeit and Dawson (1981) have shown that the ideal reaction pH for seawater is around 11.5. The reaction time of lOmin ensures more reproducible results and increases sensitivity. 

Scheme 16.6 Aldol addition of DMA to N-Cbz-aminoaldehydes catalyzed by RhuA wild type in the presence of borate buffer pH 7.5, 200 mM. (a) RhuA wild type, sodium borate 200 mM, pH 7.5 and (b) Pd/C.

Borate buffers should not be used in the presence of polyols, including carbohydrates and their derivatives, with which they may form chelate compounds they react in this way with many respiratory intermediates. Use of borate buffers in gel electrophoresis of proteins can result in spreading of the zones if fructose, ribose, sorbitol, catechol or other appropriate polyols are present to form borate complexes (Lerch and Stegemann, 1969). The increased solubility of adrenalin in borate buffers is due to complex formation as is also the improved separation of sugar phosphates chromatographically in the presence of borate buffers. Likewise, complexation of carbohydrates in german-ate or borate buffers is the basis of a suggested method for... 

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