Citrate buffer, effect

Atkin, G. E., and Ferdinand, W., Accelerated amino acid analysis studies on the use of lithium citrate buffers and the effect of //-propanol, in the analysis of physiological fluids and protein hydrolyzates, Anal. Biochem., 38, 313,1970. 

In a perfectly-buffered solution the SO2 vapor pressure will be directly proportional to the total concentration of SO2 and bisulfite, giving a linear equilibrium relationship. In simple alkali sulfite solution without added buffer, the equilibrium relationship is highly nonlinear, because H-1" accumulates as SO2 is absorbed. Under these conditions is it not possible to carry out reversible SO2 absorption/stripping in a simple system, resulting in greater steam requirements than expected with a linear equilibrium relationship. Weak acid buffers such as sodium citrate have been proposed to "straighten" the equilibrium relationship and thereby reduce ultimate steam requirements (Jl, 2, 7). Citrate buffer is attractive because it is effective over a wide range, from pH 2.5 to pH 5.5 in concentrated solutions. 

Figure 7.6 Effect of pH on the stability of AIC after incubation at 30°C for 12 h in citrate buffer with the pH adjusted to 5 (panel A), 6 (panel B), and 7.4 (panel C). The peak with a retention time >10 min is due to a buffer component. Panel C consist mainly of monomer, and the front peak observed in panels A and B is due to aggregation/unfolding of the conjugate. Analysis conditions as described in Figure 7.5.

The astatoanilines were identified by HPLC (99, 104, ISO) and TLC (160, 166, 167). The values established by extraction experiments using n-heptane and citrate buffer solutions are given in Table VI, along with estimates of the Hammett cr-values, field, and resonance effects. 

Following intravenous injection of 0-2.8 pCi/kg (104,000 Bq/kg) thorium-227 in a solution of citric acid-sodium citrate buffer in dogs, an increase in serum alkaline phosphatase measurements and hypoalbuminemia and hyperglobulinemia were observed (Stevens et al. 1967). No effects on the levels of serum glutamic pyruvic transaminase (SGPT) or serum glutamic oxaloacetic transaminase (SGOT) were found. 

Most short-term applications of EPO are non-renal related, and generally display very few side-effects i.v. administration can sometimes prompt a transient flu-like syndrome, while s.c. administration can render the site of injection painful. This latter effect appears, however, to be due to excipients present in the EOP preparations, most notably the citrate buffer. EPO administration can also cause bone pain, although this rarely limits its clinical use. 

Qualitative confirmation of the mechanisms proposed above comes from observing the effects of citrate buffer concentration and pH on swelling. There effects are displayed in Figs. 3b and 3c, respectively. With increasing citrate concentration at pH 4.0, swelling is generally depressed due to increased di- and... 

A plot of the optical absorbance at 260 nm (the wavelength of maximum light absorption by nucleic acids) versus temperature is known as a melting curve (Fig. 5-45). The absorbance is lower, by up to 40%, for native than for denatured nucleic acids. This hypochromic effect (Chapter 23) is a result of the interaction between the closely stacked bases in the helices of the native molecules. The melting temperature Tm is taken as the midpoint of the increase in absorbance (Fig. 5-45). As the percentage of G + C increases, the nucleic acid becomes more stable toward denaturation because of the three hydrogen bonds in each GC pair. Tm increases almost linearly with increases in the G + C content. In the "standard" citrate buffer (0.15 M NaCl + 0.015 M sodium citrate, pH 7.0) Eq. 5-22 holds. The exact numerical relationship depends strongly upon the ionic composition and pH of the medium.37 72 552 553... 

Carboxylic acids have been reported either to have no effect (129, ISO), to activate (135), or to inhibit (7SS) AMP aminohydrolase. While the activation of the rabbit muscle enzyme was not thoroughly examined (135), the reported inhibition of this enzyme by citrate, succinate, and maleate was most effective in the absence of activators or in the presence of ADP (133). Enzymic activity in intact myofibrils was activated by ATP, ADP, and ITP in succinate buffer but not in citrate buffer (154)-With the rat enzyme citrate, succinate, cacodylate, acetate, and lactate increased both the apparent Km and Hill slope for AMP Pmai decreased only slightly (147). 

Fig. 9. The effect of IC1 concentration on the inhibition of phosphomonoosterasc. The enzyme, 0.03 mg/ml, was incubated for 3 min at room temperature with IC1 at pH 8.1. The reaction was stopped by the addition of 30 mg % solution of albumin in citrate buffer, pH 5.5 (200 /il/0.1 ml of the incubation mixture). Then the activity of the enzyme was measured. From Bobrzecka et al. (60).

Urea (0.01 M), sodium carbonate (0.01 M), magnesium chloride (0.01 M), or distilled water can be used as microwave fluids to obtain similar results in terms of both sensitivity and intensity of the hybridization signal. Alternatively, 10 mM citrate buffer (pH 6.0) can be used as the microwave fluid. The major role of these fluids is to mediate high temperature effects, which is confirmed by the achievement of a good hybridization signal using distilled water. Note that pretreatment conditions must be optimized for every tissue type and for every cell type in a given section. 

Kahakachchi, Uden and Tyson (2004) investigated the ability of various liquids to extract As(III), As(V), DMA(V), and MMA(V) from spiked soils. The extractants included deionized water, a citrate buffer, an ammonium dihydrogen phosphate buffer, 1M phosphoric acid, 5 % acetic acid, household vinegar, 0.1 M NaOH, and even Coca Cola . After eight days, the highest extractions for As(III), MMA(V), and As(V) were achieved with NaOH at 46, 100, and 84%, respectively. A 10 mM citrate buffer was most effective with DMA(V) with about 85 % removal after eight days. 

Curl (48), in a study conducted with a synthetic orange juice, reported that the loss of ascorbic acid occurred in the presence of citric acid and potassium citrate buffer alone, but that the losses were increased by the addition of the sugars, levulose, sucrose, and dextrose, in that order. He found that darkening of the synthetic juice occurred principally when both amino acids and sugars were present and, the effect was even more pronounced by the presence of ascorbic acid. 

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