An emerging approach for studying protein-protein interaction in complexes is the combination of chemical crosslinking and mass spectrometric analysis of the crosslinked peptides (cross-links) obtained after proteolysis of the complex. This approach, however, has several challenges and limitations, including the difficulty of detecting the cross-links, the potential interference from non-informative "cross-linked peptides" (dead end and intrapeptide cross-links), and unambiguous identification of the cross-links by mass spectrometry. Thus, we have synthesized an isotopically coded ethylene glycol bis(succinimidylsuccinate) derivate (D 12 -EGS), which contains 12 deuterium atoms for easy detection of cross-links when applied in a 1:1 mixture with its H 12 counterpart and is also cleavable for releasing the cross-linked peptides allowing unambiguous identification by MS sequencing. Moreover, hydrolytic cleavage permits rapid distinguishing between different types of cross-links. Cleavage of a dead end cross-link produces a doublet with peaks 4.03 Da apart, with the lower peak appearing at a molecular mass 162 Da lower than the mass of the H 12 form of the original crosslinked peptide. Cleavage of an intrapeptide cross-link leads to a doublet 8.05 Da apart and 62 Da lower than the molecular mass of the H 12 form of the original crosslinked peptide. Cleavage of an interpeptide cross-link forms a pair of 4.03-Da doublets, with the lower mass member of each pair each shifted up from its unmodified molecular weight by 82 Da because of the attached portion of the cross-linker. All of this information has been incorporated into a software algorithm allowing automatic screening and detection of cross-links and crosslink types in matrix-assisted laser desorption/ionization mass spectra. In summary, the ease of detection of these species through the use of an isotopically coded cleavable cross-linker and our software algorithm, followed by mass spectrometric sequencing of the cross-linked peptides after cleavage, has been shown to be a powerful tool for studies of multi-component protein complexes. Large protein assemblies play a key role in many biological processes. To understand the function of these protein complexes, studies of their structural organization and the proteinprotein interfaces are of major interest to modern molecular biology. The conventional approach for studying protein-protein interactions in protein complexes is to use binary binding assays with pairs of protein subunits from the complex. However, this technique is unable to detect protein-protein interactions that are stabilized in the complex by cooperative binding and becomes laborious for multicomponent protein complexes.Current technologies for studying protein-protein interaction interfaces on a structural and molecular level, such as NMR and x-ray crystallography, are limited in application because they are restricted by considerations of protein amount, purity, concentration, size, and homogeneity (1, 2). Furthermore, these technologies are o...

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The simple methods of synthesis of hardly accessible substituted biphenyl, dibenzothiophene, carbazole and phenanthrene derivatives were elaborated starting from dimethyl 4,4'-biphenyldicarboxylate. The series of new luminophores with extended π-conjugated chains based on combinations of biphenyl, carbazole, dibenzothiophene, phenanthrene fragments and alternating phenyl, vinyl or heterocyclic units were synthesized by the Wittig and the Knoevenagel reactions of corresponding aromatic dialdehydes and different CH-acids or phosphonium salts. Investigation of the effect of various substituents on the luminescent properties has been presented. The new luminophores could be used as emissive or charge transport layers in organic light emitting diodes (OLEDs).

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