A top-down approach to protein structure studies using chemical cross-linking and Fourier transform mass spectrometry

In a preliminary communication we described a top-down approach to the determination of chemical cross-link location in proteins using Fourier transform mass spectrometry (FT-MS). We have since extended the approach to use a series of homobifunctional cross-linkers with the same reactive functional groups, but different cross-linker arm lengths. Correlating cross-linking data across a series of related linkers allows the distance constraint derived from a cross-link between two reactive side chains to be determined more accurately and increases the confidence in the assignment of the cross-links. In ubiquitin, there are seven lysines with primary amino groups and the amino terminus. Disuccinimidyl suberate (DSS, cross-linker arm length = 11.4 A), disuccinimidyl glutarate (DSG, cross-linker arm length = 7.5 A) and disuccinimidyl tartrate (DST, cross- linker arm length = 5.8 A) are homobifunctional cross-linking reagents that react specifically with primary amines. Using tandem mass spectrometry (MS/MS) on the singly, internally cross-linked precursor ion of ubiquitin, we found cross-links with DSS and DSG between the amino terminus and Lys 6, between Lys 6 and Lys 11, and between Lys 63 and Lys 48. Using disuccinimidyl tartrate (DST), the shortest cross-linker in the series, only the cross-links between the amino terminus and Lys 6, and between Lys 6 and Lys 11 were observed. The observed cross-links are consistent with the crystal structure of ubiquitin, if the lysine side chains and the amino terminus are assumed to have considerable flexibility. In a separate study, we probed the reactivity of the primary amino groups in ubiquitin using the amino acetylating reagent, N-hydroxy succinimidyl acetate (NHSAc), and a top-down approach to localize the acetylated lysine residues. The reactivity order obtained in that study (M1 approximate, equals K6 approximate, equals K48 approximate, equals K63) > K33 > K11 > (K27, K29), shows that the cross-link first formed in ubiquitin by reaction with DSS and DSG occurs between the most reactive residues.     

1H NMR STUDY OF MIXED-LIGAND LANTHANIDE COMPLEXES. STOICHIOMETRY AND TEMPERATURE SENSITIVITY OF PARAMAGNETIC CHEMICAL SHIFTS OF PRASEODYMIUM β-DIKETONATES AND THEIR COMPOUNDS WITH 18-CROWN-6

Journal of Structural Chemistry - Complexes [(Pr(DPM)3)2], [Pr(DPM)3(18-crown-6)], [(Pr(DPM)3)2(18-crown-6)], [Pr(DPM)(PTA)(18-crown-6)]+ and the temperature sensitivity of paramagnetic...     

Messung der Sto?frequenz in Gasentladungen verschiedener mehratomiger Gase

Ohne Zusammenfassung     

Fine structure in the decay of deformed proton emitters: nonadiabatic approach

The coupled-channel Schrodinger equation with outgoing wave boundary conditions is employed to study the fine structure seen in the proton decay of deformed even- N, odd- Z rare earth nuclei 131Eu and 141Ho. Experimental lifetimes and proton-decay branching ratios are reproduced. Variations with the standard adiabatic theory are discussed.     

Spurious resonances in a version of the algebraic Resonating-Group Method

It is shown that the conditions claimed to transform the algebraic version of the Resonating-Group Model, originally invented for scattering problems, into a complex eigenvalue problem corresponding to resonant states are necessary but not sufficient. This can be concluded from the fact that false resonances are produced along with true ones. They can be distinguished and discarded by introducing an arbitrary non-linear parameter. The true solutions are invariant against this parameter but the false ones can be swept out even into non-physical regions of the energy.Devoted to Prof. E.W.Schmid on the occasion of his 60th birthday