Dimethylsulfoxide DMSO Concentration

In most cases, the test compounds are dissolved in DMSO and are added from a source plate into the assay. Thus, the tolerance of the assay for DMSO should be tested, by looking at the activities at various increasing concentrations of DMSO. Generally, enzymatic or biomolecular binding assays are more tolerant of high DMSO concentrations (often up to 5% to 10% DMSO). Cell-based assays usually can tolerate up to 0.5% DMSO. 

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Sutton [1.15] studied the question of how quickly solutions with certain CPAs (GL, dimethylsulfoxide (DMSO) and others] have to be cooled in order to avoid crystallization. At 100 °C/min concentration of 42.1 % DMSO and 48.5 % for GL are necessary to achieve the glass phase. With a 32.5 % solution of (2R.3R)-(-)butan-2,3-dio, the same effect can be accomplished at = 50 °C/min. In Fig. 1.18 Sutton (Fig. 11 from [1.114]) showed, that polyethylene glycol with a molecular weight of 400 (PEG 400) reduced the critical cooling rate down to approx. 25 °C/min. The addition of PEG 8000 [1.115] improved the protection of lactate dehydrogenase (LDH) by maltodextrins, if maltodextrins with low dextrose equivalents are used. 

Figure 3.22. Fluorescence titrations of anthrylboronic acid 16 (0.75 jiM) at pH 7.4 (20 mAf phosphate buffer) as a function of polyol concentration (+, fructose , t,l,l-tris(hydroxymethyl)ethane a, glucose +, ethylene glycol). All solutions contain 1% (v/v) dimethylsulfoxide (DMSO). (Reproduced from Ref. 26. Copyright 1992 American Chemical Society.)...

The second factor that contributes to this variability is that in most high throughput screens the compounds are usually only tested once, at a single concentration. Consequently, differences in compound concentration and purity will have a large effect on the accuracy of the assay data. The differences in compound concentration can be due to differences in compound preparation or compound stability in dimethylsulfoxide (DMSO). The concentration of the test compound can even be varied depending on the length of time the DMSO stock solution is exposed to the atmosphere, as DMSO can take up water (69,70). 

Some gels were synthesized which underwent the phase transition twice as the solvent composition was monotonically varied from 0% to 100%. Figure 30 shows the swelling behaviors of NIPA (open circles) and acrylamide (solid circles) gels in a mixture of dimethylsulfoxide (DMSO) and water [24]. When the DMSO concentration was lower than 33%, the NIPA gel was slightly swollen. Above 33% DMSO, a discrete transition to a collapsed state occurred. However, the gel showed a discontinuous re-swelling at 90%. Such reentrant behavior has also been observed when temperature or pH were used as variables. 

Eggins and McNeill compared the solvents of water, dimethylsulfoxide (DMSO), acetonitrile, propylene carbonate, and DMF electrolytes for C02 reduction at glassy carbon, Hg, Pt, Au, and Pb electrodes [78], The main products were CO and oxalate in the organic solvents, while metal electrodes (such as Pt) which absorb C02 showed a higher production for CO. In DMF, containing 0.1 M tetrabutyl ammonium perchlorate and 0.02 M C02 at a Hg electrode, Isse et al. produced oxalate and CO with faradaic efficiencies of 84% and 1.7%, respectively [79], Similarly, Ito et al. examined a survey of metals for C02 reduction in nonaqueous solution, and found that Hg, Tl, and Pb yielded primarily oxalate, while Cu, Zn, In, Sn, and Au gave CO [80, 81]. Kaiser and Heitz examined Hg and steel (Cr/Ni/Mo, 18 10 2%) electrodes to produce oxalate with 61% faradaic efficiency at 6 mA cm-2 [82]. For this, they examined the reduction of C02 at electrodes where C02 and reduction products do not readily adsorb. The production of oxalate was therefore explained by a high concentration of C02 radical anions, COi, close to the surface. Dimerization resulted in oxalate production rather than CO formation. 

Compounds are normally stored as a stock solution to be dispensed as needed by robotic equipment. Dimethylsulfoxide (DMSO) is a preferred solvent for several reasons. First, in low concentrations, DMSO is well tolerated in most assays. Second, the low melting point of DMSO (18 °C) allows samples to be easily frozen. Compounds that are stored in the solid state are less prone to decompose. Third, DMSO is less volatile than most organic solvents. Decreased volatility minimizes solvent evaporation, so concentrations remain nearly constant over prolonged storage. Maintaining a known concentration is vital. The activity of each screened molecule is related by a concentration-effect relationship. If the concentration of a stock solution is not accurate, then any subsequent assessment of activity will also be incorrect.1... 

Another approach to the problem of the value of n is to determine the degree of hydration of the transition state in an aprotic, nearly anhydrous, solvent. This has been done (Williams and Kreevoy, unpublished data) for ethyl vinyl ether hydrolysis in dimethylsulfoxide (DMSO). In nearly anhydrous DMSO containing very low concentrations of hydro-... 

The toxicity tests were conducted by exposing the organisms to solutions of at least five concentrations with a number of variable replicates from test to test. Single chemicals of high purity were initially dissolved in dimethylsulfoxide (DMSO) not exceeding the concentration of 0.01% (v/v) in the test solution.15,12... 

In 1972, Williamson43 used two organisms, Chara corralina and Nitella translucens, to examine the effects of CB on cytoplasmic streaming. Whole cells from rhizoidal and small leaf internode tissue were treated with the metabolite at concentrations of 1-50 pg/mL in dimethylsulfoxide (DMSO). There was a concentration, time dependent result so that 50 pg/mL inhibited streaming in a few minutes, whereas it took 6 h to induce the same effect with 1 pg/mL. Washing the cells with a DMSO solution, used at the same concentration in which the CB had... 

If the substrate is a synthetic peptide, a stock solution can be prepared by dissolving the lyophilized peptide in anhydrous, Ar-saturated dimethylsulfoxide (DMSO). The stock solution with a typical substrate concentration of 5 mM can be kept in aliquots at -20°C. 

When the production of the secondary metabolites coincides with the death and general lysis of the cells, the recovery of the product is simply a matter of separation from the spent production solution downstream of the reactor. An example of this type of operation was initially used in Japan during the production of shikonin. However, if the secondary metabolites are stored in the vacuole of the cells and the cells remain viable but dormant during the production phase, then a permeabilizing agent such as dimethylsulfoxide (DMSO), detergents, proteins, and antibiotics may be employed in some cases in concentrations that make the cells leak product out but maintain cell viability. Success for this type of product recovery has been reported in C. roseus, Datura innoxia, and Daucus carota cell cultures. 

Drugs can be insoluble or poorly soluble in cell culture medium. Therefore, stock solutions of the drugs can be made in 100% dimethylsulfoxide (DMSO) at 50 mM. The highest testable drug concentration should preferably not contain DMSO concentrations higher than 1% to avoid toxicity of DMSO to the cell cultures. 

The optimum concentration of PEG (30-50%) for fusion is very close to the toxic concentration (at or above 50%). Toxicity of the different batches of PEG may vary considerably. It can be advantageous to include 5% dimethylsulfoxide (DMSO) in the PEG preparation (Norwood et al., 1976 Fazekas de St. Groth and Scheidegger, 1980). 

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