Estimation of molecular weights of peptides by determination of height equivalent to a theoretical plate in size-exclusion chromatography

The analysis of the flow-rate required to obtain the optimum height equivalent to a theoretical plate, HETP, has been used to estimate the molecular weight, MW, of peptides in size-exclusion chromatography. A straight line is obtained when log MW is plotted against the flow-rate which gives the optimum HETP. This relationship holds even for peptides which adsorb to column packings. The typical quantity of peptide required is 1 nmol and analysis time was less than 2 h. The method is applied to peptides of 200–10,000, and the precision is ±20%. The method may be applicable to the analysis of MW for all classes of compounds.     

A Hamilton formalism for evolution equations with odd variables

Summary A certain super Hamiltonian formalism for evolution equations with odd variables is constructed by establishing the notion of super Hamiltonian operator. A useful criterion for the operator of the special class to be super Hamiltonian is presented, by means of which the two differential operators derived by Manin- Radul and the author from the SKP hierarchy are proved to be super Hamiltonian.     

Regio- and stereoselective synthesis of allylsilanes using (methylphenylamino) tributylphosphonium iodine

Regio- and stereoselective synthesis of variously substituted allylsilanes is achieved by organocuprate-mediate γ-coupling of allylic alcohols using the title reagent ($\text{1}$).     

Syntheses of cyclopentyl nucleoside (−)-neplanocin A through tetrazole-fragmentation from cyanophosphates

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Localization or delocalization in the electronic structure of Creutz-Taube-type complexes in aqueous solution

Creutz-Taube complex, [(NH3)5Ru-pyrazine-Ru(NH3)5]5+ (1), and its analogues, [(NH3)5Os-pyrazine-Os(NH3)5]5+ (2), [(NH3)5Ru(4,4'-bipyridine)Ru(NH3)5]5+ (3), and [(NH3)5Os(4,4'-bipyridine)Os(NH3)5]5+ (4), were theoretically investigated by the combination of a two-state model and the dielectric continuum model. Their electronic structures are very sensitive to the metal, ligand, and solvent. In the gas phase, the electronic structures of 1-4 would be completely delocalized. In aqueous solution, that of 3 becomes localized because the polar solvent stabilizes the localized electronic structure with the large dipole moment. However, 1 and 2 are still delocalized in aqueous solution. In 4, the electronic structure would be localized when the dihedral angle between two pyridyl rings is 80 degrees , while it would become delocalized when the angle is small. The origins of the difference are the smaller overlap integral and larger energy difference between two diabatic states, of which electronic structure is almost localized on each metal center.