Purification and characterization of a native zinc-binding high molecular weight multiprotein complex from human seminal plasma

The seminal plasma comprises secretions from various accessory sex glands. During fertilization spermatozoa undergo complex sequences of precisely timed events that are regulated by the activation of different intracellular signaling pathways. The precision and efficacy of these pathways are often influenced by the assembly and interactions of multiprotein complexes, thereby directing the flow of regulatory information. Our knowledge about these protein complexes present in human seminal plasma (HuSP) is limited. Here we report the identification and characterization of a native high molecular weight zinc-binding multiprotein complex from HuSP by utilizing 2-DE followed by MS. Twenty-six proteins representing isoforms and/or fragments of 11 different proteins were found to be assembled in this complex. Prostate-specific antigen, zinc α2-glycoprotein, prostatic acid phosphatase, and prolactin inducible protein were the major proteins of this complex. Dynamic light scattering experiments revealed changes in aggregation pattern accompanied with deviation from physiological pH and in presence of SDS. However, no significant changes were observed in the presence of physiological ligands such as zinc and fructose. The present study will be useful and contribute to guide the future studies performed for elucidation of biological significance of this native complex in HuSP.     

First stereoselective total synthesis of panaxjapyne C

The first stereoselective total synthesis of polyacetylene panaxjapyne C is described. The key reactions include regioselective opening of the epoxide and Cadiot-Chodkiewicz cross-coupling reactions. l-Ascorbic acid was used as a chiral pool material for the construction of the both terminal acetylenes.     

Phonon anomalies and structural transition in spin ice Dy2Ti2O7: a simultaneous pressure‐dependent and temperature‐dependent Raman study

We revisit the assignment of Raman phonons of rare‐earth titanates by performing Raman measurements on single crystals of O¹⁸ isotope‐rich spin ice and nonmagnetic pyrochlores and compare the results with their O¹⁶ counterparts. We show that the low‐wavenumber Raman modes below 250 cm⁻¹ are not due to oxygen vibrations. A mode near 200 cm⁻¹, commonly assigned as F_2g phonon, which shows highly anomalous temperature dependence, is now assigned to a disorder‐induced Raman active mode involving Ti⁴⁺ vibrations. Moreover, we address here the origin of the ‘new’ Raman mode, observed below T_C ~ 110 K in Dy₂Ti₂O₇, through a simultaneous pressure‐dependent and temperature‐dependent Raman study. Our study confirms the ‘new’ mode to be a phonon mode. We find that dT_C/dP = + 5.9 K/GPa. Temperature dependence of other phonons has also been studied at various pressures up to ~8 GPa. We find that pressure suppresses the anomalous temperature dependence. The role of the inherent vacant sites present in the pyrochlore structure in the anomalous temperature dependence is also discussed. Copyright © 2012 John Wiley & Sons, Ltd.     

Analysis of volume dependence of Grüneisen ratio

Various models on volume dependence of the Grüneisen ratio have been analyzed in the present study. The Sharma model [Mod. Phys. Lett. B 22/31 (2008) 3113] is found to be similar to that used by Nie [Phys. Stat. Sol. (b) 219 (2004) 241] on the basis of approximation made by Jeanloz [J. Geophys. Res. 94 (1989) 5929]. The Nie expression is amended in a manner so that the resulted expression follows the constraint of high pressure thermodynamics in the limit of infinite pressure. The newly developed relationship is applied successfully on materials for which experimental data are accessible such as epsilon-iron, NaCl, Li, Na, and K.     

Compression dependence of αKT for ionic solids

In the present study, the compression dependence of αK_T is analyzed using Anderson-Isaak equation along with Stacey's equation of state for ionic solids such as NaCl and MgO. It is found that the value of αK_T decreases with increasing compression and attains a minimum, after which it increases with increasing compression along an isotherm. It is also found that αK_T tends to infinity as P→∞ or V→0. The presented nature of αK_T is valuable to understand the thermoelastic and thermodynamic properties of MgO and NaCl at high compressions and at high temperatures.     

Analysis of K-prime equations of state

We present an analysis of the $K$-prime equations of state (EOS) due to Keane and Stacey. It is found that the two EOS differ significantly from each other in some important respects. $K$-prime represents the pressure derivative of the bulk modulus. It is shown that the volume dependence of $K$-prime and higher derivative properties predicted from the Keane EOS are compatible with those predicted from Stacey’s reciprocal $K$-prime EOS only when the Murnaghan approximation is valid. It has been emphasized that the Stacey EOS is more appropriate for describing the relationship between pressure and the bulk modulus and its pressure derivative. The results based on the two EOS have been compared and discussed.     

Switch-less operation of a TEA CO2 laser with extended electrodes

We report here the reliable and efficient operation of a mini-TEA CO₂ laser utilizing uniform field electrodes wherein the parallel spark channels of the preioniser, an integral part of the laser, functioned as a switch as well as a source of UV photons. The operation of the laser has been realized up to a maximum energy loading of ∼197 J/l atm under widely varying gas composition including helium lean as well as helium-free gas mixtures. Under most optimized conditions the laser operated with an efficiency of ∼7.1%. The spatially symmetric nature of the emission from the laser in spite of the one sided preionisation points to the effectiveness of the excitation circuit employed here to energise the laser.     

Experimental and computational studies of ring‐opening polymerization of ethylene brassylate macrolactone and copolymerization with ε‐caprolactone and TBD‐guanidine organic catalyst

The ring‐opening polymerization (ROP) of ethylene brassylate, catalyzed by the cyclic guanidine 1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene (TBD) is reported. Several experimental parameters were evaluated for bulk ROP process and polyesters, resulting in molecular weights between 3 and 15 kg mol^?1. End‐group analysis by ¹H nuclear magnetic resonnance (NMR) and matrix assisted laser desorption ionization time of flight computational studies supports the dual behavior of TBD, which can act as both a catalyst and initiator of the polymerization process. Under optimum conditions, semicrystalline poly(ethylene brassylate‐co‐ε‐caprolactone) random copolymers were synthesized. Depending on the comonomer content, our results showed a range of melting temperatures between 39 and 69 °C. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 552–561     

Photochemical activity of membrane-localised polyketide derived marine natural products

Marine organisms rely upon complex bio-chemical systems to manage photo-induced oxidative damage as part of a sophisticated chemical defense. Using a combination of synthetic chemistry and biophysical techniques, we provide evidence to support the notion that marine derived polyene γ-pyrone metabolites of sacoglossan molluscs become localised at cell membranes where they influence the total absorption of the harmful radiation by the lipid membrane, thereby functioning as sunscreen agents. We also report two new hyperperoxide analogues of the putative polyene biosynthetic precursors that themselves are likely candidate natural products.