Tris-maleate buffer

A. 0.1 A/Tris-maleate buffer 100 ml (25 ml stock + 75 ml distilled water)... 

The thermostability of the crude lipase produced by Candida ant-arctica is demonstrated in Figure 1. The remaining activities after incubation for 30 min at different temperatures in 50 irM Tris-maleate buffer, pH 7.0, were measured using olive oil as substrate at 40°C, followed by end-point titration of the liberated fatty acids. 

The thermostabilities of the two enzymes were compared after 30 min of incubation at 75°C in 50 uM Tris-maleate buffer, pH 7.0. 

In the author s laboratory, HMM and LMM were obtained by trypsin digestion. LMM was purified by reprecipitation in 75% ethanol and redissolved in 0.5 M KC1-0.05 M tris-maleate buffer, pH 6.5, followed by ultracentrifugation (39). 

LMM, after dialysis against a solution of 0.05 M KC1-0.005 M tris-maleate buffer (pH 6.2), also exhibited a decreased capacity to form well-ordered paracrystals or tactoids as examined by electron microscopy (Figure 5). It is interesting that several half-reconstituted paracrystals (Figure 5b) were found after 6 weeks of frozen storage. 

Fig. 18. Effect of Triton X-100 concentration on the response amplitude of a triglyceride-sensitive FET sensor , 0.4 mM tributylin in 10 mM Tris-maleate buffer O, 0.4 mM triolein in 1 mM Tris-maleate buffer V, 2 mM triolein in the 1 mM buffer. (Reproduced from Nakako et al. (26), with permission.)...

The performance of the triglyceride-sensitive FET biosensor in 0.001 M Tris-maleate buffer soludons, pH 7.0, containing 10% Triton X-100, is shown in Fig. 19. A linear response is obtained up to 1 mM triolein. The triglyceride FET biosensor is useful for the determinadon of triolein over the concentration range of 0-3 mM. 

Listed below are some acids and bases that are useful in preparing buffers for enzyme assays. The choice of a particular compound depends on many factors. For example, multicarboxylic acids would be poor choices for reactions involving metal ions as cofactors amino acids may be poor choices for reactions involving amino acids as substrates. The number of buffer components can be kept to a minimum by using an acid and a base to cover the desired region. For example, maleic acid and Tris can be mixed to produce Tris-maleate buffers of pH 5.7 to 8.6 (rather than using maleic acid-NaOH and Tris-HCl). 

The TRIS-maleate buffer solutions for pH setting were prepared by adding appropriate quantity of 0.2 NaOH to 0.2 M TRIS and maleic anhydride mixture and diluted to 0.05 M concentration. 

Spectrofluoremetric studies were carried out to determine the correlation between the fluorescence intensity of the SNARF-1 dextran/urease capsules and the pH of the medium. Both the capsule samples were stored for 10 min in the 0.05 M TRIS-maleate buffer at pH in the range 5.5-9. The excitation wavelength was 540 nm. The capsules fluorescence spectra of the first sample are shown in Figure 2. The spectra obtained for both samples were similar. The encapsulated dye is capable to provide information of the medium acidity in a reasonably wide range of pH. It is seen that fluorescence... 

Comparison of tumor and non-tumor cell precipitation by polycation treatment in tris-maleate buffer... 

FIGURE 20.2 Fluorescence spectra of the SNARF-1 dextran/urease capsules in the 0.05 M TRIS-maleate buffer at pH in the range 5.5-9. 

FIGURE 20.3 Change of fluorescence intensity ratio -R at 580 and 640 nm for curve 1- SNARF-1 dextran water solution curve 2 containing SNARF-1 dextran capsules curve 3 SNARF-1 dextran/urease capsules (sample I, 0.6 pg dye/capsule curve 4 SNARF-1 dextran/ urease capsules (sample II, 0.2 pg dye/capsule) in 0.05 M TRIS-maleate buffer at pH in range 5.5-9. 

It is worth to notice, that this cahbiation curve is obtained for SNARF-1 dextran/ urease capsule in pure water without substantial contamination of aity salt, which could bulFer the systems and spoil truly picture for urea detection. We carried out experiments to build a similar calibration curve in the presence of the 0.001 M TRIS-maleate buffer (were used solutions with the pH 6.5 and 7.5) but it resulted in overwhelming effect of pH buffering. Buffering the solution eliminates the pH change caused in a course of enzymatic reactions. Thus, it sets a hmit for detection of urea concentration using SNARF-l-dextran/urease capsules. However the calibration in conditions of particular experimental system is reasonable at salt free solution assumption. Summarizing, one can state the presented in Fig. 20.7 calibration curve as suitable for estimation of urea concentrations in-situ in water solutions. 

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