Protein analysis chambers

More recent publications on sulfosuccinates have confirmed the minimal or close to zero skin and eye irritation caused by these products. In a general screening of product safety evaluation methods the authors [16] rejected the sulfosuccinate from further consideration in the statistical analysis of experimental data (variance analysis) because the product had not shown any irritation in the Duhring-Chamber test. The sulfosuccinate (based on fatty alcohol ethoxy late) was tested in a screening with 14 other surfactants, namely, alkyl sulfates, sulfonates, ether sulfates, and a protein fatty acid condensation product. 

A representative IEF purification with the Rotofor that demonstrates the effectiveness of refractionation is shown in Fig. 8. The starting material for this fractionation was 150 mg of crude snake venom containing 2% (w/v) pH 3-10 carrier ampholytes. Aliquots of each of the 20 fractions from the run were analyzed in polyacrylamide IEF gels in pH 3-10 gradients. The focusing patterns of the proteins in the odd-numbered fractions are shown in Fig. 8a. The protein of interest (outlined with an oval) was found in fractions 10, 11, and 12. These three fractions were pooled, diluted with water to the volume of the separation chamber and refractionated. No additional ampholytes were added to the pooled material. IEF analysis of the refractionated material (Fig. 8 b) revealed that fraction 13 contained the protein of interest in nearly pure form. 

Pseudomolecular Ions. In contrast to the traditional MS, the highest mass peaks in ESI/APCI spectra are not always the molecular ion of interest. Instead, pseudomolecular ions, or noncovalent complex ions, are commonly observed. The pseudomolecular ions are generally formed by the analyte-adduct interaction in the solution system that is preserved as a result of the soft ionization of the ESI/APCI process. These ions are also formed by analyte-adduct gas-phase collisions in the spray chamber [49]. The exact mechanisms of how the analyte adducts are formed in ESI/APCI still remain unresolved at this point. More often than not, the adduct ion formation is a major cause for the low detection limit for ESEAPCI MS. However, these associative processes have also created interest in the study of drug-protein/ drug-oligonucleotide gas-phase complexes that benefit from the ability of ESI/APCI MS analysis. 

At the present time the hydrolytic methods of choice for tryptophan analyses appear to be with methanesulfonic acid in the presence of added 3-(2-aminoethyl) indole (see Moore 1972) or with NaOH in the presence of starch (Hugh and Moore 1972). Both methods will be described below, but it should be noted here that hydrolysis with NaOH has the advantage that carbohydrate in the protein sample does not affect the yields of tryptophan as it does in the acid hydrolysates. Other methods of tryptophan analysis involving spectrophotometry (Goodwin and Morton 1946 Edelhock 1967), titration with N-bromo-succinimide (Spande and Witkop 1967), or the formation of colored derivatives (Spies and Chambers 1948 Barman and Koshland 1967 ... 

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