Evaluation of parameters critical to observing proteins inside living Escherichia coli by in-cell NMR spectroscopy

Our recently developed in-cell NMR procedure now enables one to observe protein conformations inside living cells. Optimization of the technique demonstrates that distinguishing the signals produced by a single protein species depends critically on protein overexpression levels and the correlation time in the cytoplasm. Less relevant is the selective incorporation of (15)N. Poorly expressed proteins, insoluble proteins, and proteins that cannot tumble freely due to associations within the cell cannot yet be observed. We show in-cell NMR spectra of bacterial NmerA and human calmodulin and discuss limitations of the technique as well as prospects for future applications.     

Influence Exerted by Pyrite Impurity in the Initial Graphite on Properties of Residual Graphite Hydrosulfates

The influence exerted by the particle size and the distribution of sol impurities in the initial graphite, and also by pyrite additives, on the properties of residual graphite hydrosulfates synthesized by oxidation in the CrO₃-H₂SO₄ system was studied.     

Composition and Structure of Films Formed in Etching of Nickel in a Ni(NO3)2 Solution with NiCl2 and NaNO2 Additives

The composition and structure of films formed in etching of nickel in a Ni(NO₃)₂ solution in the presence of Cl^- and NO₂ ^- ions was studied.     

Photolysis of hexamethyldisilane at 206 nm

The photolysis of Me₆Si₂ at 206 nm results in two main decomposition processes: simple Si---Si bond breaking with a quantum yield of Φ = 0.21 ± 0.03, and Me₃SiH elimination with the concomitant formation of Me₂SiCH₂ with Φ = 0.18 ± 0.01. There is also a minor decomposition channel with a very small quantum yield, Φ = (5.6 ± 0.2) × 10⁻³, which results in the formation of Me₄Si and Me₂Si. The main fate of the excited Me₆Si₂ molecule produced during photolysis is stabilization by collisional deactivation. The end products observed indicate that the reaction pathways followed by the main intermediates, Me₃Si and Me₂SiCH₂, are the same as those found in the photolysis of Me₄Si (Ahmed et al., J. Photochem. Photobiol. A: Chem. 86 (1995) 33).     

Acylation of n-phenyl-2-(indol-3-yl)succinimides

Treatment of N-phenyl-2-(1-R-indol-3-yl)succinimides with acetyl perchlorate leads to acylation of the benzene ring of the indole substituent.L. M. Litvinenko Institute of Physico-Organic and Carbon Chemistry, Ukrainian Academy of Sciences, Donetsk 340114. A. N. Kosygin State Textile Academy, Moscow 117918, GSP-1. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 85–88, January, 1997.     

Synthesis of the first stable carborane containing simple enol

A carborane-containing stable simple enol — 1-2-isopropyl-o-carboran-I-yl)-1-phenyl2-mesityl-2-lrydroxyctlrylcne — has been synthesized. This enol does not isomerize to the starting ketone or keto-enol mixture even after prolonged heating in benzene in the presence of CF₃COOH.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1561–1563, June, 1996.     

Resolution of a paradox in the electrophoresis of DNA in agarose gels

A paradox was observed in a previous study of the electrophoresis of linear DNA fragments in agarose gels (D. L. Holmes and N. C. Stellwagen, Electrophoresis 1990, 11, 5-15). The pore size of the agarose matrix was more accurately determined if the root-mean-square radius of gyration was used to measure DNA macromolecular size. However, the Ogston equations were obeyed and other gel parameters such as the apparent fiber radius and fiber volume appeared to be better described if the geometric mean radius was used to measure DNA size. This paradox can be resolved if relative mobilities (with respect to the smallest DNA molecule in the data set) are used to construct the Ferguson plots, instead of absolute mobilities. Using relative mobilities and the root-mean-square radius of gyration, the Ogston equations are obeyed and the pore size of the matrix is consistent with values determined by other methods.     

Fluorimetric determination of anionic surfactants by extraction as safranine-T ion-pairs

A simple and rapid method is proposed for the spectrofluorimetric determination of anionic surfactants. It is based on formation of an ion-pair at pH 2 with safranine-T and its subsequent extraction into chloroform. Fluorescence intensity is increased by a factor of about 5 with respect to that of the reagent. The calibration graph is linear in the concentration range 0.015–0.40 mg l^?1 dodecyl sulfate; the relative standard deviation is 5.6% at 0.22 ml l^?1 surfactant. The method is applied to determine anionic surfactants in city waste-waters, giving recoveries close to 100%.