Protein-doped crystals

For producing protein-doped crystals following Beavis and Chait (1996), the matrix is dissolved to saturation in a suitable solvent and then mixed with protein/peptide solution and dried on the sample carrier of the mass spectrometer. Mixtures of water with organic solvents such as acetonitrile, methanol, or propanol in the ratio given in the table serve as a solvent for the matrix. 

According to Vorm et al. (1994) and Vorm and Mann (1994), fast drying yields smaller and more evenly distributed protein-doped crystals. Hence, the protein/matrix droplets are often dried in a vacuum. Hewlett-Packard offers a a device with which you can visually track the crystallization in the vacuum. 

The quality of the protein-doped cryst s is experimentally crucial and decisive for the quality of their spectrum. Only proteins incorporated in matrix crystals jump into the gas phase. Not every matrix is suited for every protein. Which matrix delivers the best results is not predictable. You have to try things Table 7.1 shows suitable matrices. 

To examine the ability of membranes to prepare samples with known contaminants, we contaminated the above peptide and protein solution with 5% glycerol and 500 mM NaCl. In addition to preventing effective crystallization of analyte samples with matrix on conventional stainless steel surfaces, glycerol and sodium contaminants are frequently present in biological samples. Doped samples were prepared for MALDI-TOF analysis by saturating the membrane with MeOH, immediately followed by the addition of 1 ul of the sample. The membrane was washed 3 times with 3-6 ml 70% methanol in water and allowed to dry after each wash. Once dry, lul saturated matrix solution was added to the sample spot. 

Proteins with chemical functions such as, for example, enzymes, adopt their native macroconformations under physiological conditions. In general, their shapes are very rigid and compact on account of the many inter- and intramolecular bonds these proteins mostly occur in spheres or ellipsoids. The external shape can often be determined by hydrodynamic measurements or electron microscopy. Information on the internal structure can often be obtained by X-ray measurements on protein crystals doped with heavy metals (see also Section 5.3.1). 

Wilson-Kubalek et al. also produced specifically and nonspecifically functionalized unilamellar lipid tubules by using mixtures of a tubule-forming galactosylceramide and various charged or derivatized lipids [166]. Thus, nickel-doped lipids allowed the helical crystallization of histidine-tagged proteins. The authors also reproduced the helical crystallization of streptavidin. They even obtained helical arrays of relatively small proteins, such as actin and annexin, as well as large macromolecules, such as RNA polymerase (Fig. 21). 

Zhitomirsky et al. [8] have shown that electrodeposition can also be used to prepare films of hybrid composites. Cathodic electrodeposition of iron oxide nanoparticles were deposited with a polyelectrolyte matrix. Inorganic proteins and fibroblasts have been deposited on single crystal Si and Si3N4, and doped Si substrates... 

Biopolymers, like nucleic acids (DNA and RNA), proteins, polysaccharides, lipids, and so on. have fundamental significance in life processes. Since the mid-1980s, highly conducting polymers, like doped different polyacetylenes (1) and (2) (SN) (3), or the TCNQ-TTF system (4) and (5), with quasi-one-dimensional alternating stacks of the two different types of molecule embedded in a three-dimensional molecular crystal, and PPV (6), have become objects of extensive experimental investigations because they are also candidates for the discovery of new physical phenomena, such as solitons, polarons and bipolarons, and superconductivity with higher transition temperatures (T ). 

In 2007, our group reported the hrst microscopic observation of two-photon excited Tb(III) emission, in bulk crystals of tris-dipicolinate complex or in protein crystals (e.g., HEWL, hen eggs white lysozyme [102]) doped with the same complex supress crystals [60]. In spite of the very low 2PA efficiency of this complex, the microscopy experiment was successful... 

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