Investigation of skin secretory peptidome of <Emphasis Type=Italic>Rana lessonae</Emphasis> frog by mass spectrometry

Amphibian skin secretion represents a cerain scientific interest as a source of biologically active natural peptides. In the present research skin peptidome of wide-spread European frog Rana lessonae (Camerano, 1882) was studied for the first time ever. Peptide sequencing was accomplished with Fourier transform ion cyclotron resonance mass spectrometer in collision-induced and electron capture dissociation modes. A portion of amphibian peptides contains intramolecular C-terminal disulfide cycle which obstructs mass spectrometric sequencing. Two methods were utilized to overcome this difficulty: reduction with dithiotreithol followed by thiol group alkylation and oxidation into sulfonic acid groups with performic acid. Integrated approach employed in the present study allowed the identification of 49 peptides (of 6 to 37 amino acid residues), including 19 novel species.     

Expansion isentropes of the explosion products of condensed explosives

The expansion isentropes of the explosion products of two TNT/RDX compositions (50/50 and 25/75) have been investigated. Attention is concentrated on the little-studied region of pressures below 100 kbars. Data on the expansion isentropes were obtained by measuring the shock wave parameters in various media (aluminum, plexiglas, polystyrene foam, argon, air). Points were obtained on the shock Hugoniots of argon precom-pressed to 10, 15, and 50 atm. An equation of state of the explosion products that satisfactorily describes the experimental material obtained is formulated.In conclusion the authors thank L. V. Al'tshuler for his constant interest in their work and valuable advice and N. M. Filipchuk and I. A. Dolgov for assisting with the experiments.     

Interaction of strongly nonlinear waves on the free surface of a dielectric liquid in a horizontal electric field

The nonlinear dynamics of the free surface of an ideal dielectric liquid with a large relative permittivity in a strong horizontal electric field has been considered. It has been demonstrated that the interaction between oppositely propagating solitary waves in arbitrary geometry is elastic: they conserve their energy and momentum. The interaction between waves has been numerically simulated with the use of conformal variables. It has been shown that the interaction deforms the waves; this effect is weak for waves with a relatively small amplitude: deformation for oppositely propagating waves with the identical shape is determined by the fourth power of their amplitude. At multiple collisions of strongly nonlinear waves, a tendency to the formation of singularities, i.e., points with a high energy density of the field, is observed.     

Optimization of immunoaffinity enrichment and detection: toward a comprehensive characterization of the phosphotyrosine proteome of K562 cells by liquid chromatography-mass spectrometry

Phosphorylation of protein tyrosine residues regulates many cell functions and has also been proved to be involved in oncogenesis. Thus, the identification of the phosphotyrosine (pTyr) proteome of cells is a very important task. Since tyrosine phosphorylation represents only around 1% of the total human phosphoproteome, the study of pTyr proteins is rather challenging. Here we report the optimization study of the phosphotyrosine proteome using K562 cells as a model system. A substantial segment of the phosphotyrosine proteome of K562 cells was characterized by immunoaffinity enrichment with 4G10 and PYKD1 antibodies followed by LC-MS/MS analysis. 480 non-redundant pTyr peptides corresponding to 342 pTyr proteins were found. 141 pTyr peptides were not described elsewhere. The mass spectrometry approach involving high-resolving FTMS analysis of precursor ions and subsequent detection of CID fragments in a linear ion trap was considered as optimal. For detection of low abundant pTyr peptides pooling of individual immunoaffinity enrichments for one LC-MS/MS analysis was crucial. The enrichment properties of the monoclonal PYKD1 antibody were presented for the first time, also in comparison to the 4G10 antibody. PYKD1 was found to be more effective for protein enrichment (1.2 and 5% efficiency at peptide and protein level correspondingly), while 4G10 showed better results when peptide enrichment was performed (15% efficiency versus 3.6% at protein level). Substantially different subsets of the phosphoproteome were enriched by these antibodies. This finding together with previous studies demonstrates that comprehensive pTyr proteome characterization by immunoprecipitation requires multiple antibodies to be used for the affinity enrichment.     

Pretransitional phenomena in acrylate-based liquid crystal networks

The static Kerr effect is used to study the pretransitional phenomena in polymer networks even in the presence of inherent optical anisotropy of crosslinked materials. The pretransitional phenomena in a liquid crystal polymer and its networks are sensitive to the structure of the crosslinks and their distribution within the network. The bulky network junctions distributed more or less homogeneously within the network serve as defects which decrease the hypothetical second order phase transition temperature T* and suppress the nematic fluctuations in the polymer network above the clearing point.     

Formation of conic cusps at the surface of liquid metal in electric field

The formation dynamics is studied for a singular profile of a surface of an ideal conducting fluid in an electric field. Self-similar solutions of electrohydrodynamic equations describing the fundamental process of formation of surface conic cusps with angles close to the Taylor cone angle 98.6° are obtained. The behavior of physical quantities (field strength, fluid velocity, surface curvature) near the singularity is established.     

On the theory of the dynamical properties of nematics

The Leslie–Ericksen coefficients of a thermotropic nematic are determined by using an approximate solution of the Fokker–Planck equation for the one-particle distribution function over orientations of the nematic molecules. The results show that the well-known Doi–Edwards theory of the dynamical properties of nematics leads to a qualitatively wrong result for the Leslie angle. The “isotropic medium - nematic” (I–N$I–N$) transition induced by the shear flow is considered. When the temperature decreases, the I–N$I–N$ transition in the shear flowing system takes place at the temperature _T1$T_1$ higher than the temperature _Tc$T_c$ of the equilibrium transition in the motionless system. The interface boundary in this case is parallel to the plane formed by the flow velocity and its gradient. When the shear flowing nematic phase is heated, the N–I$N–I$ transition occurs at another temperature _T2$T_2$, and the following inequalities _T1>_T2>_Tc$T_1>T_2>T_c$ hold. In this case the boundary between the isotropic and nematic phases is perpendicular to the flow velocity. Thus, unlike the equilibrium phase transition, a temperature hysteresis of the phase transition is expected.     

Algorithm for Constructing Exact Solutions of the Problem of Unsteady Plane Motion of a Fluid with a Free Surface

JETP Letters - Unsteady plane potential flows of an ideal incompressible fluid with a free surface in the absence of external forces and capillarity are studied. An algorithm to construct exact...     

Transition radiation of modulated electron beam in strongly inhomogeneous plasma

A formula for the transition radiation of a modulated electron bean in a strongly inhomogeneous plasma is derived in a given-current approximation. Nonmonotonic variation of the transition-radiation power is detected when the inhomogeneity parameter for the beam emerging from the plasma is varied. The analytic results are confirmed by numerical calculations.Kiev State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 37, No. 2, pp. 194–199, February, 1994.