Phycobiliproteins encapsulated in sol-gel glass

Light transducing phycobiliproteins are encapsulated in optically transparent sol-gel matrices. Absorption and fluorescence spectroscopies are used to characterize the effect of the sol-gel encapsulation on the conformation and aggregation states of the three major phycobiliproteins present in phycobilisomes: phycoerythrin, phycocyanin, and allophycocyanin. It is found that the effects of sol-gel entrapment on the spectroscopic properties are significantly different for the three phycobiliproteins. The results indicate that phycoerythrin undergoes only minor change in its native structure when entrapped in sol-gel. However, significant changes in conformation and aggregation state occur when phycocyanin and allophycocyanin are entrapped in sol-gel matrices. A thin film of sol-gel encapsulated phycoerythrin is also coated on an optical fiber surface and strong fluorescence from the evanescent wave excitation is detected. The potential applications of sol-gel encapsulated phycobiliproteins in biosensors are discussed.     

The relative basicity of sulfur containing esters

The relative gas phase proton affinities for an amide, ester, and thiolester have been established as CH₃CONHCH₃ > CH₃COSCH₃ > CH₃COOCH₃ using ion cyclotron resonance techniques. A dithioester is more basic than the thiolester: CH₃CSSCH₃ > CH₃COSCH₃. d-Orbitals are unimportant in the electronic structure of thiolesters.     

The magnetic dipole moment of 55Co

The ground state g-factor for ⁵⁵Co has been measured as $\text{¦g¦= 1.378±0.001}$ by the technique of nuclear magnetic resonance on oriented nuclei. The temperature dependence of γ-ray anisotropy in the ⁵⁵Fe daughter decay determines both the 1408 keV level spin and the ⁵⁵Co ground state spin to be $\text{7}\text{2}$, and yields values of mixing ratios in the 1037 keV β-transition and the 477 keV γ-transition. The configuration mixing model is used to discuss 1f_{$\text{7}\text{2}$} moment systematics.     

Gas phase studies of N-nitrosamines by ion cyclotron resonance spectroscopy

The gas phase basicities of a series of cyclic and acyclic N-nitrosamines were determined by ion cyclotron resonance techniques. The fragmentation pattern and ion-molecule reactions of these compounds are discussed in terms of high resolution mass spectrometry and deuterium labeling. The presence of a unique rearrangement of the molecular ion is discussed in terms of specific ion-molecule proton transfer reactions and fragment ion products.