Sensitivity enhanced, protein

The 140-residue protein AS is able to form amyloid fibrils and as such is the main component of protein inclusions involved in Parkinson s disease. Full-length 13C/15N-labelled AS fibrils and AS reverse-labelled for two of the most abundant amino acids, K and V, were examined by homonuclear and heteronuclear 2D and 3D NMR.147 Two different types of fibrils display chemical shift differences of up to 13 ppm in the l5N dimension and up to 5 ppm for the backbone and side-chain 13C chemical shifts. Selection of regions with different mobility indicates the existence of monomers in the sample and allows the identification of mobile segments of the protein within the fibril in the presence of monomeric protein. At least 35 C-terminal residues are mobile and lack a defined secondary structure, whereas the N terminus is rigid starting from residue 22. In addition, temperature-dependent sensitivity enhancement is also noted for the AS fibrils due to both the CP efficiency and motional interference with proton decoupling.148... 

Pelletier MJ, Altkom R (2001) Raman sensitivity enhancement for aqueous protein samples using a liquid-core optical-fiber cell. Anal Chem 73(6) 1393-1397... 

Huang, X. Prince, A. Corso, T.N. Van Pelt, C. Howe, K. Zhang, S. Direct Elution of Preconcentrated Protein Digests from Packed Pipette Tips to Chip-Based NanoESI-MS/MS for Enhanced Protein Identification Sensitivity, in Proceedings of the 52nd ASMS Conference on Mass Spectrometry and Allied Topics, Nashville, Tennessee, May 23-27,2004. 

The NMR data acquisition sensitivity depends on the NMR probe performance. Recently, a remarkable sensitivity enhancement was achieved by a cryogenic probe.122 This technology reduces the thermal noise of the NMR signal by cooling the device by liquid helium. In practice, the enhancement strongly depends on the sample condition. Usually, the S/N ratio increases by factors from two to four for protein solution. 

The most important recent advance of the solution NMR pulse sequence methodology is transverse relaxation optimized spectroscopy (TROSY) due to its significant sensitivity enhancement for large proteins by increasing the lifetimes of NMR signals.17 120 124-126... 

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