Crystal structure of nucleotide-free dynamin

Dynamin is a mechanochemical GTPase that oligomerizes around the neck of clathrin-coated pits and catalyses vesicle scission in a GTP-hydrolysis-dependent manner. The molecular details of oligomerization and the mechanism of the mechanochemical coupling are currently unknown. Here we present the crystal structure of human dynamin 1 in the nucleotide-free state with a four-domain architecture comprising the GTPase domain, the bundle signalling element, the stalk and the pleckstrin homology domain. Dynamin 1 oligomerized in the crystals via the stalks, which assemble in a criss-cross fashion. The stalks further interact via conserved surfaces with the pleckstrin homology domain and the bundle signalling element of the neighbouring dynamin molecule. This intricate domain interaction rationalizes a number of disease-related mutations in dynamin 2 and suggests a structural model for the mechanochemical coupling that reconciles previous models of dynamin function

Glycan labeling strategies and their use in identification and quantification

Most methods for the analysis of oligosaccharides from biological sources require a glycan derivatization step: glycans may be derivatized to introduce a chromophore or fluorophore, facilitating detection after chromatographic or electrophoretic separation. Derivatization can also be applied to link charged or hydrophobic groups at the reducing end to enhance glycan separation and mass-spectrometric detection. Moreover, derivatization steps such as permethylation aim at stabilizing sialic acid residues, enhancing mass-spectrometric sensitivity, and supporting detailed structural characterization by (tandem) mass spectrometry. Finally, many glycan labels serve as a linker for oligosaccharide attachment to surfaces or carrier proteins, thereby allowing interaction studies with carbohydrate-binding proteins. In this review, various aspects of glycan labeling, separation, and detection strategies are discussed

Speciation of organic selenium compounds using reversed-phase liquid chromatography and inductively coupled plasma mass spectrometry. 3. Application of sector field instrument with low and high mass resolution for selenium speciation in herring gull eggs

A HPLC procedure based on reversed phase chromatography with methanol as the eluent for the speciation of organic Se compounds has been developed to study the appearance of Se species in herring gull eggs collected from mud flats of the North Sea. The extraction of Se species by using hot water was limited to a recovery of 8% only. The multielement capability of ICP-MS was exploited to obtain elemental correlation, and for Se compounds (selenocystine, selenocystamine, selenomethionine, selenoethionine) were used as standards. Among these only the presence of selenocystamine was evident, and correlations of this fraction with Cu, As and S became obvious