The effect of phosphoryl oxygen on the intermolecular action of alanine and lysozyme

It was found that N-diisopropyloxyphosphoryl alanine (DIPP-Ala) could form adduct with hen egg white lysozyme (HEWL) as shown in electrospray ionization mass spectroscopy (ESI-MS), but the non-phosphorylated alanine couldn't. The capability for formation of DIPP-Ala dimmer was more stronger than that of alanine. It suggested that a specific non-covalent complex was formed in the solution phase and could be transferred to the gas phase via electrospray ionization (ESI). The results implied that phosphorylated alanine possessed relatively stronger affinities for protein and formed non-covalent complexes with protein more easily than alanine. Using Tripos force field, molecular mechanics calculation on DIPP-Ala dimmer showed that such non-covalent adduct formation was due to the intermolecular hydrogen bond

Synthesis and properties of block solution-polymerized styrene-butadiene rubber for damping material with broad temperature range

Block solution-polymerized styrene-butadiene rubber (SSBR) with two different compositions and ratios was designed and synthesized by living anionic polymerization with styrene and butadiene as monomers, n-butyllithium as initiator, 2,2-bis(tetrahydrofuran)propane as modifier, and cyclohexane as solvent. The microstructure, chemical composition and molecular weight and its distribution of the block SSBR were characterized by proton nuclear magnetic resonance spectrometer and gel permeation chromatographer, and the mechanical properties and dynamic mechanical properties of the block SSBR vulcanizate were analyzed by rubber tension machine and dynamic mechanical analyse respectively. The results showed that the molecular structure of the block SSBR met the desired molecular structure. The vulcanizate had good mechanical properties and dynamic mechanical properties. The higher the mass ratio of the soft block to the hard block of the block SSBR, the wider the damping temperature range. As the soft block had lower bound styrene content, the damping temperature range of the block SSBR was more widened. When mass fraction of bound styrene of the two blocks of block SSBR was 15% and 50%, and the mass ratio was 7/3, the efficient damping temperature range exceeded 53 ℃ with loss factor of not less than 0.3