Immobilization of RNase S-Peptide on a single-stranded DNA-fixed gold surface and effective masking of its surface by an acridinyl poly(ethylene glycol)

Oligonucleotide-peptide conjugate was synthesized by coupling of RNase S-peptide to a 24-mer single-stranded DNA (ssDNA) oligonucleotide to be immobilized on its complementary ssDNA oligonucleotide-fixed gold surface of sensor chip or electrode. Immobilization of on the ssDNA-fixed gold surface through DNA duplex formation was confirmed by quartz crystal microbalance (QCM) and electrochemical measurements. After treating with a synthetic acridinyl poly(ethylene glycol) (APEG), specific interaction of S-protein with the S-peptide immobilized on the gold surface was demonstrated by QCM without nonspecific adsorption of unrelated proteins such as BSA and RNase A at the surfaces. This result suggested that the acridine parts of APEG could bind to the DNA duplex on the gold surface and the poly(ethylene glycol) parts were fastened on the surface to resist the adsorption of proteins. Thus, the combination of oligonucleotide-peptide conjugate, ssDNA-fixed chip and APEG with effective masking property provides a new tool for the analysis of specific peptide-protein interactions without disturbance by other unrelated proteins.     

Highly effective, easily accessible screw-sense-determining end group in the asymmetric polymerization of 1,2-diisocyanobenzenes

Enantiopure helical poly(quinoxaline-2,3-diyl) was formed stereoselectively in the polymerization of 1,2-diisocyanobenzene using a new organopalladium initiator bearing the (4S,5S)-N-acyl-4,5-dihydro-4,5-diphenyl-1H-imidazol-2-yl group as the polymer-end screw-sense-determinant.     

Acid-labile surfactant improves in-sodium dodecyl sulfate polyacrylamide gel protein digestion for matrix-assisted laser desorption/ionization mass spectrometric peptide mapping

Mass spectrometry (MS) together with genome database searches serves as a powerful tool for the identification of proteins. In proteome analysis, mixtures of cellular proteins are usually separated by sodium dodecyl sulfate (SDS) polyacrylamide gel-based two-dimensional gel electrophoresis (2-DE) or one-dimensional gel electrophoresis (1-DE), and in-gel digested by a specific protease. In-gel protein digestion is one of the critical steps for sensitive protein identification by these procedures. Efficient protein digestion is required for obtaining peptide peaks necessary for protein identification by MS. This paper reports a remarkable improvement of protein digestion in SDS polyacrylamide gels using an acid-labile surfactant, sodium 3-[(2-methyl-2-undecyl-1,3-dioxolan-4-yl)methoxy]-1-propanesulfonate (ALS). Pretreatment of gel pieces containing protein spots separated by 2-DE with a small amount of ALS prior to trypsin digestion led to increases in the digested peptides eluted from the gels. Consistently, treatment of gel pieces containing silver-stained standard proteins and those separated from tissue extracts resulted in the detection of increased numbers of peptide peaks in spectra obtained by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOFMS). Hence the present protocol with ALS provides a useful strategy for sensitive protein identification by MS.     

Immobilization of sunflower trypsin inhibitor (SFTI-1) peptide onto a gold surface and analysis of its interaction with trypsin

Sunflower trypsin inhibitor (SFTI-1) derived peptide having one disulfide bond could be immobilized via a thiol-disulfide exchange reaction onto a gold surface on a quartz crystal microbalance (QCM) chip. This permitted quantitative analysis of the specific interaction with trypsin.     

Radiation-induced polymerization at high dose rate. III. Isoprene in bulk

Radiation-induced polymerization of isoprene in bulk state was studied at 25°C in a wide dose rate range. Variations of the rate of polymerization and molecular weight of the products were essentially the same as those observed in the monomers which were capable of both radical and cationic polymerizations. At low dose rate, 7.0-230 rad/sec, radical polymerization took place. At high dose rate, 8.8 × 10³-2.2 × 10⁵ rad/sec, radical and cationic polymerizations took place concurrently. The average molecular weight of the high-dose-rate product was about 850, independent of dose rate. The microstructure of the products at high dose rate consisted mainly of trans- 1,4 units with only about 7% of cis- 1,4 and 10% of 3,4-vinyl units. The residual unsaturation in the high-dose-rate products was 90%. Decreases in cis units and residual unsaturation at high dose rate were accounted for by the change in predominant mechanism of polymerization with dose rate.     

Unusually High Barriers to Rotation Involving the Tetrahedral Carbon Atom

Rotation about CC single bonds in suitably substituted compounds gives rise to rotational isomers (also called rotamers) which can be isolated if the barrier to rotation is high enough. The present article considers derivatives of triptycene and fluorene whose barriers to rotation are of the order of 30 kcal/mol.     

Control of helical chirality of poly(quinoxaline‐2,3‐diyl)s based on postpolymerization modification of the terminal group by small chiral molecules

Poly(quinoxaline‐2,3‐diyl)s having a terminal formyl or boronyl group were prepared by living polymerization of 1,2‐diisocyanobenzenes using organopalladium initiators bearing a protected formyl or boronyl group. Poly(quinoxaline‐2,3‐diyl)s were successfully deracemized by reacting them with small optically active molecules at their terminal formyl or boronyl group, leading to the induction of optically active helical structures. Poly(quinoxaline‐2,3‐diyl) having terminal formyl groups was converted to one‐handed helical polymer, in which the screw‐sense excess was 68% (84:16). The helix sense of the boronyl‐terminated poly(quinoxaline‐2,3‐diyl) was reversibly controlled by attaching and removing the chiral group. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012