Structures unique label possibility

Whereas chemical structures will always be the primary vehicle for visual communication, it is possible that journal articles will be reporting a unique label representing a chemical structure in the near future, especially because this label will already allow the searching of chemical structures contained in publications indexed using Web-based search engines. For more on this, see Appendix 8-1. 

Multidimensional NMR methods, combined with isotope labeling, can provide access to virtually every atom in a molecule, unique for protein structural studies. This not only allows characterization of the structure and interaction of proteins in their native milieu, but also provides unparalleled possibilities to obtain a complete atomic-level resolution picture of protein dynamics in a time range from picoseconds up to seconds, the range where most motions relevant to protein function take place. A significant number of 15N and 13C relaxation studies have been performed on a large number of proteins in the last... 

The elucidation of the structure, dynamics and self assembly of biopolymers has been the subject of many experimental, theoretical and computational studies over the last several decades. [1, 2] More recently, powerful singlemolecule (SM) techniques have emerged which make it possible to explore those questions with an unprecedented level of detail. [3-55] SM fluorescence resonance energy transfer (FRET), [56-60] in particular, has been established as a unique probe of conformational structure and dynamics. [26-55] In those SM-FRET experiments, one measures the efficiency of energy transfer between a donor dye molecule and an acceptor dye molecule, which label specific sites of a macromolecule. The rate constant for FRET from donor to acceptor is assumed to be given by the Forster theory, namely [59,61-64]... 

To minimize the potential for collision-cell cross talk, it is prudent to find product ions of a given compound that are unique to its structure. A practical example would be that when using stable label isotopes as internal standards, use a product ion which contains the stable label moiety in order to insure distinct product ion masses for the analyte and internal standard. Where it is not possible to find unique MRM product ions for components, it may be necessary to increase the time delay between monitored ion transitions (sometimes called the interchannel delay) to allow the collision cell to reequilibrate and empty itself of the prior ion load. For example, if two ion transitions are monitored in an MRM experiment, and both monitor the identical product mlz ion, the interchannel delay may need to be increased from 100 to 300 msec. This additional time allows the instrument to clear the collision cell of holdover ions. Another option to minimize cross talk is to insert additional dummy MRM channels that monitor a different product ion ml% into the instrument acquisition method, allowing the collision cell to reequilibrate. 

TTX is a specific blocking agent of the voltage-dependent sodium (Na) channel, and occupies a unique position as a toxin for the Na channel. By applying TTX labeled with radioisotope, it became possible to isolate the channel molecule itself [11]. As a result, the primary structure of the Na channel was clarified by applying gene recombination technology [12]. 

The method of choice for the determination of most vitamins is HPLC due to its high separation capability, its mild analytical conditions, and the possibility to use various specifically adapted detection methods, e.g., LTV, fluorescence, or MS detection. All fat-soluble vitamins and most water-soluble vitamins have chromophores suitable for UV detection. Separation of vitamers and stereoisomers can be achieved. If a higher sensitivity is required HPLC with fluorescence detection can be used, either directly (e.g., vitamins A and E) or after derivatization (e.g., thiamine). A further improvement in sensitivity and specificity has been achieved by introducing HPLC with mass spectrometric detection in vitamin analysis. Due to the structural information retrievable, e.g., molecular mass, fragmentation pattern, this is the method of choice for analysis of samples with complex mixtures or low vitamin concentrations. Examples for the use of HPLC-MS in vitamin analysis include the determination of 25-hydroxy-D3 and pantothenic acid. However, one drawback of mass spectrometry is the need for an isotopically labeled reference compound for reliable quantification. Due to the structural complexity of many vitamins, these reference compounds are often expensive and difficult to synthesize. An interesting unique application is the determination of vitamin B12 by HPLC-IPC-MS, which is possible due to its cobalt content. 

While we are applying recent heteronuclear NMR methods (14, 15) to l N-labeled samples of the 43mer RNA, the 28mer offers a unique possibility to test the limits of well-established homonuclear NMR methods which work well for a molecular size under 20 nucleotides (16). High resolution structures of larger RNA fragments have been determined with either special spectral deconvolution techniques (17) or partial deuteration of RNA samples (18). 

The FRRPP process has been proposed to generate unique materials with certain programmable structures. Some of the unique features involve polymeric surfactants that have the ability to be dispersed in water at relatively low concentrations, and to be environmentally responsible formulations which allow for wide area/volume delivery. They would also have the ability to penetrate low porosity solids, such as soil, cement, rock, masonry with modest pressure drop requirements. If labeled, these surfactants can be applied on various surfaces or within porous stmctures for subsequent detection of changes in surface/underground structures. These materials can also be transformed into a nonflowing gel, and finally into a hard rubber dry sealant material. Other transformations of interest could be investigated from various possible polymeric surfactants that can be synthesized using the FRRPP process. 

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