Comprehensive and uniform synthesis of all naturally occurring phosphorylated phosphatidylinositols

Studies of cellular signal transduction mechanisms involving receptor-mediated generation of inositol phosphates and phosphorylated phosphatidylinositols require easy access to these naturally occurring products. Although numerous synthetic methods have been developed during the past decade, most of these methods suffer from excessive length and lack of generality. In this work we describe the comprehensive and uniform synthesis of all naturally occurring phosphatidylinositols such as phosphatidylinositol, phosphatidylinositol 3-phosphate, 4-phosphate, 5-phosphate, 3,4-bisphosphate, 3,5-bisphosphate, 4,5-bisphosphate, and 3,4,5-trisphosphate, featuring both saturated and unsaturated fatty acid chains.     

A Fully Polynomial Approximation Scheme for Minimizing Makespan of Deteriorating Jobs

A fully polynomial approximation scheme for the problem of scheduling n deteriorating jobs on a single machine to minimize makespan is presented. Each algorithm of the scheme runs in O(n ⁵ L ⁴³) time, where L is the number of bits in the binary encoding of the largest numerical parameter in the input, and is required relative error. The idea behind the scheme is rather general and it can be used to develop fully polynomial approximation schemes for other combinatorial optimization problems. Main feature of the scheme is that it does not require any prior knowledge of lower and/or upper bounds on the value of optimal solutions.     

Reinvestigation of zinc(II) complexation by 2-thiophenecarboxylic hydrazide: X-ray structure of tris(2-thiophenecarboxyhydrazide)zinc(II) tetrachlorozincate(II) di(ethanol) and vibrational spectroscopy of its decomposition product

Reaction of ZnCl₂ and 2-thiophenecarboxylic hydrazide (tch), in ethanol resulted in the crystalline product [Zn(tch)₃][ZnCl₄] · 2EtOH, which slowly decomposes losing solvent molecules. The structure of the first compound has been determined by the single crystal X-ray method. Analysing the IR spectra of both compounds it has been found that the complex [Zn(tch)₃]²⁺ cation and [ZnCl₄]²⁻ anion are preserved after crystal decomposition. Vibrational spectra of the obtained substances were interpreted with the assistance of DFT calculations and metal isotope as well as deuterium replacement.     

Comparative study of beryllium,magnesium and zinc phthalocyanine complexes with 4-picoline

Three new Be(II), Mg(II) and Zn(II) phthalocyaninato(2-) complexes with 4-picoline (4-Mepy) in the crystalline form have been obtained by recrystallization of the respective M(II)Pc in 4-picoline under water-free conditions. BePc and ZnPc in 4-picoline solution form 4 + 1 coordinated complexes, while the 4-Mepy molecules biaxially ligate MgPc. The planar phthalocyaninato(2-) macroring of BePc and ZnPc upon mono-axial ligation by the 4-Mepy molecule adopts the saucer-shape form. The interaction of the central M(II) with the ligated 4-Mepy molecule leads to a deviation of the metal from the centre cavity by ∼0.31 Å and ∼0.35 Å in the Be and Zn phthalocyaninato complexes, respectively. In MgPc, the Pc ring upon biaxial ligation retains a planar configuration. The axial M(II)–N(4-Mepy) bond is longer than the four equatorial M(II)–N_iso bonds in Mg and Zn phthalocyaninato complexes, while in the Be complex the opposite relation between the axial and equatorial Be–N bonds is observed. Thermogravimetric analysis for all these compounds exhibits only one slope down, due to the loss of 4-Mepy molecules from the complexes, which transform finally into the respective M(II)Pc complexes in the β-form.     

Structural, spectroscopic, and electrochemical studies of the complexes [Ni2(mu-CNR)(CNR)2(mu-dppm)2](n+) (n = 0, 1, 2): unusual examples of nickel(0)-nickel(I) and nickel(0)-nickel(II) mixed valency

Reaction of Ni(COD)(2) (COD = cyclooctadiene) with dppm (dppm = bis(diphenylphosphino) methane) followed by addition of alkyl or aryl isocyanides yields the class of nickel(0) dimers Ni(2)(mu-CNR)(CNR)(2)(mu-dppm)(2) (R = CH(3) (1), n-C(4)H(9) (2), CH(2)C(6)H(5) (3), i-C(3)H(7) (4), C(6)H(11) (5), t-C(4)H(9) (6), p-IC(6)H(4) (7), 2,6-(CH(3))(2)C(6)H(3) (8)). The cyclic voltammograms of the dimers exhibit two sequential single electron oxidations to the +1 and +2 forms. Specular reflectance infrared spectroelectrochemical (IRSEC) measurements demonstrate reversible interconversions between the neutral Ni(0) dimers and their +1 and +2 forms. Bulk samples of the +2 forms are prepared by chemical oxidation using [FeCp(2)][PF(6)], while the +1 forms are prepared by the comproportionation of neutral and +2 forms. The neutral complexes 6 and 8 were characterized by X-ray diffraction as symmetric, locally tetrahedral binuclear Ni(0) complexes. The +2 forms of these complexes, 6(2+) and 8(2+), have asymmetric structures with one locally square planar and one locally tetrahedral metal center, evidence for a Ni(II)-Ni(0) mixed valence state. The X-ray structural characterization of 6(+) is symmetrical and qualitatively similar to that of the neutral complex 6. The +1 forms all exhibit intense near IR electronic absorptions that are assigned as intervalence charge transfer (IVCT) bands. On the basis of structural, spectroscopic, and electrochemical data, the +1 forms of the complexes, 1(+)-8(+), are assigned as Robin-Day class III, fully delocalized Ni(+0.5)-Ni(+0.5) mixed valence complexes.     

General Synthesis of Phosphatidylinositol Phosphates

Abstract

A general method for synthesis of 3-phosphorylated phosphatidylinositols is described.

Phosphatidylinositol (PI) and phosphatidylinositol phosphates (PIP_n), such as PI-4-P, PI-4,5-P₂ undergo receptor-mediated cleavage by phosphatidylinositol-specific phospholipase C, and are precursors of second messengers important in diverse cellular signaling pathways. In contrast, the 3-phosphorylated phosphatidylinositols, such as PI-3-P (1), PI-3,4-P₂ (2) and PI-3,4,5-P₃ (3), which are formed in response to signals of growth factors, are resistant to hydrolysis by this enzyme, and their cellular function is only beginning to emerge [1,2]. These compounds are formed in minute quantities, and therefore have to be synthesized for many practical applications.     

Signal Processing in Normal Pulse Voltammetry by Means of Dedicated Mother Wavelet

In the work, a new signal processing algorithm is presented and applied for the transformation of the sigmoidal shaped curves, registered in normal pulse voltammetry (NPV), to the peak shaped curves. The method is based on the continuous wavelet transform (CWT) and specially constructed mother wavelet defined using the ideal wave‐shaped curve. Transformation of the signal, elimination of noises and separation of overlapping data can be achieved in one step by means of proposed procedure. The operation and effectiveness of the algorithm is presented using ideal, noised and overlapping simulated curves. The process of simultaneous determination of lead and indium as well as transformation of curves registered for elements' ions: lead, indium, thallium and cadmium is described. The obtained results show substantial improvement of the performance of NPV.