Of 2-mercaptoethanol

Fig. 3. Sodium dodecyl sulfate—polyacrylamide gel electrophoretic pattern for molecular weight standards (lane 1) water-extractable proteins of defatted soybean meal (lane 2) purified IIS (glycinin) (lane 3) and purified 7S (P-conglycinin) (lane 4) where the numbers represent mol wt x 10. The gel was mn in the presence of 2-mercaptoethanol, resulting in the cleavage of the disulfide bond linking the acidic (A bands) and basic (B bands) polypeptides of the...

The oxirane ring-opening reaction requires the presence of a basic catalyst. An acidic catalyst also works, but the polymerization of the oxirane limits its usehilness. In the case of 2-mercaptoethanol (eq. 8), the product has been found to be autocatalytic, ie, the product is a catalyst for the reaction. 

The by-products of these reactions are sulfides. The sulfide formed in the synthesis of 2-mercaptoethanol, 3-thia-l,5-pentanediol (thiodiglycol), has a variety of uses ranging from lubricant additive intermediates to textile finishing. 

In the presence of 2-mercaptoethanol o-phthalaldehyde reacts with primary amines to yield fluorescent isoindole derivatives [20] ... 

HPLC The compound F obtained is further purified on a column of TSK DEAE-5PW, using 40% aqueous acetonitrile containing 85 mM NaCl and 3 mM NaHCC>3. The final yield of F is about 2 mg (purity 80-90%) from 500 g of frozen specimens. A small amount of 2-mercaptoethanol added at the last desalting step may significantly improve the purity of the final product. 

The aqueous ferricyanide oxidation of 2-mercaptoethanol to the disulphide is also complex kinetically" . In the pH range used (l.S. l) no complication from ionisation of the thiol is expected. Individual decays of oxidant concentrations are initially second-order but eventually become almost zero-order. For both second-and zero-order paths the rate depends on the first power of the thiol concentration and the former path is retarded by increasing the acidity, an approximately inverse relation existing above pH 3.2. Addition of ferrocyanide transforms the kinetics the rapid, second-order path is inhibited and the zero-order path is accelerated until, at 10 M ferrocyanide, the whole of the disappearance of oxidant is zero-order. Addition of Pb(C104)2, which removes product ferrocyanide, greatly enhances the oxidation rate and the consumption of oxidant becomes rs/-order. Two routes are considered to co-exist (taking due account of the acidity of ferrocyanic acid), viz. 

Protective effect of Na and K against inactivation of Na/K ATPase by high concentrations of 2-mercaptoethanol at high temperatures. Biochim. Biophys. Acta 821, 115-120. 

Only after the oligodeoxynucleotide component of the conjugate was replaced with d(T)io could the adducts of external nucleophiles be observed. This alternative oligodeoxynucleotide was chosen based on the lack of detectable reaction between T and the parent ortho-QMS 1 Aqueous incubation of the d(T)10 QM conjugate in the absence and presence of 2-mercaptoethanol yielded the water and 2-mercaptoethanol adducts, respectively, as characterized by HPLC and mass spectroscopy.71... 

Add 3 ml of the detergent Brij-35 (as a 30 percent solution) and 2 ml of 2-mercaptoethanol to 950 ml of Fluoraldehyde Reagent Diluent (all reagents from Thermo Fisher). 

Add 2-mercaptoethanol to the reaction solution to obtain a final concentration of 20 mM. Mix and incubate for 10 minutes at room temperature. Note If the protein being activated is sensitive to this level of 2-mercaptoethanol, instead of quenching the reaction chemically, the activation may be terminated by desalting (step 5). 

Add 1.4 pi of 2-mercaptoethanol to each ml of the reaction mixture to quench excess EDC. Sonicate the QD solution several times to maintain particle dispersion. 

Figure 19.19 An Ellman s assay may be done to determine the maleimide activation level of SMCC-derivatized proteins. Reaction of the activated carrier with different amounts of 2-mercaptoethanol results in various levels of sulfhydryls remaining after the reaction. Detection of the remaining thiols using an Ellman s assay indirectly indicates the amount of sulfhydryl uptake into the activated carrier. Comparison of the Ellman s response to the same quantity of 2-mercaptoethanol plus an unactivated carrier indicates the absolute amount of sulfhydryl that reacted. Calculation of the maleimide activation level then can be done.

Butyltin trichloride reacts with the sodium salt of 2-mercaptoethanol to give a trinuclear oxathiastannolane, which, with butylmagnesium chloride, gives an oxathiaststannolane dimer, which can be prepared also from the reaction of butanestannonic acid with 2-mercaptoethanol (Equation (172)).s... 

A comparative study was made of the RP-HPLC analysis of free amino acids in physiological concentrations in biological fluids, with pre-column derivatization by one of the four major reagents o-phthalaldehyde (73) in the presence of 2-mercaptoethanol, 9-fluorenylmethyl chloroformate (90), dansyl chloride (92) and phenyl isothiocyanate (97, R = Ph) (these reagents are discussed separately below). Duration of the analysis was 13-40 min. Sensitivity with the latter reagent was inferior to the other three however, its use is convenient in clinical analysis, where sample availability is rarely a problem. The derivatives of 73 were unstable and required automatized derivatization lines. Only 92 allowed reliable quantation of cystine. All four HPLC methods compared favorably with the conventional ion-exchange amino acid analysis188. 

The regioselectivity of Michael additions of thiolates to 2,4-dienones can be altered drastically by variation of the reaction conditions and addition of Lewis acids to the reaction mixture. Lawton and coworkers examined the reaction of 2-mercaptoethanol with l-(3-nitrophenyl)-2,4-pentadien-l-one and observed a high regioselectivity in favor of the 1,6-addition product at 45 °C (equation 42)123,124. Lowering of the reaction temperature caused an increase in the amount of 1,4-adduct, and at —40°C, a product ratio of 40 60 was found. These events suggest that kinetic control favors the 1,4-addition product whereas the 1,6-adduct is thermodynamically more stable. If, however, the reaction was carried out with a complex of the dienone and titanium tetrachloride, only the 1,4-adduct was isolated after hydrolytic workup123. Obviously, this product is trapped as a metal chelate which prevents formation of the 1,6-adduct by retro-Michael/Michael addition. In the absence of the chelating Lewis acid, the 1,4-addition product can indeed be converted... 

Wash the blot till no smell of 2-Mercaptoethanol can be detected. 

A. bronchisepticus was cultivated aerobically at 30 °C for 72 h in an inorganic medium (vide supra) in 1 liter of water (pH 7.2) containing 1 % of polypeptone and 0.5 % of phenylmalonic acid. The enzyme was formed intracellularly and induced only in the presence of phenylmalonic acid. All the procedures for the purification of the enzyme were performed below 5 °C. Potassium phosphate buffer of pH 7.0 with 0.1 mM EDTA and 5 mM of 2-mercaptoethanol was used thoughout the experiments. The enzyme activity was assayed by formation of pheylacetic acid from phenylmalonic acid. The summary of the purification procedure is shown in Table 2. The specific activity of the enzyme increased by 300-fold to 377 U/mg protein with a 15% yield from cell-free extract [9]. One unit was defined as the amount of enzyme which catalyzes the formation of 1 mmol of phenylacetic acid from phenylmalonic acid per min. 

Figure 2.12 MS data of tethered complexes, (a) Tethering experiment between TS and 10 disulfides equilibrated for 1 hour, (b) tethering with varying concentrations of 2-mercaptoethanol, and (c) tethering with varying pool size of disulfides. Reproduced from Reference 31 with permission of the National Academy of Sciences, USA. Copyright (2000) National Academy of Sciences, U.S.A.

To avoid reduction of disulfide bonds, use 0.2 mg/ml tyrosin instead of 2-mercaptoethanol. 

The achiral dicarbonyl complex 1 has been shown to undergo facile 1,4-addition of amines and thiols to generate the elaborated acyl complexes 2. The more nucleophilic sulfur atom of 2-mercaptoethanol selectively adds to such complexes45. 

SDS-PAGE, presence of 2-mercaptoethanol [17] <15> 2 44000, SDS-PAGE, presence of 2-mercaptoethanol, high speed sedimentation equilibrium centrifugation of urea-treated enzyme [22] <2> 2 43195, calculated from sequence of cDNA [40] <5> 2 49000, SDS-PAGE [19] <14> 2... 

Carbonic anhydrase activities of the egg shells are inhibited by reaction with p-mercuribenzoate by blocking reactive SH-groups of the enzyme. Omission of 2-mercaptoethanol from buffer solutions for extraction and fractionation also resul-... 

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