The SAIL (Stereo-Array Isotope Labeling) method is an ingenious NMR approach for protein structure analysis. Developed by Professor Kainosho from Tokyo Metropolitan University, this novel approach is based on his experience accumulated over a lifetime of research on the development of stable isotope labeling for biomolecules. SAIL utilizes the simple concept that certain stereospecific patterns of isotopes are optimal for protein NMR analysis and that these depend on the structures of the individual amino acids. SAIL amino acids are “designer molecules?Eengineered to provide all essential information and to minimize problems from unwanted spin-spin coupling and unfavorable relaxation mechanisms. This is achieved by building into each amino acid a particular pattern of isotopes: 1H or 2H for hydrogen, 12C or 13C for carbon, and 14N or 15N for nitrogen. Once incorporated into a protein, these carefully designed SAIL amino acids enable the researcher to carry out a three-dimensional NMR structural analysis rapidly and with high accuracy. SAIL labeling enables structural studies of proteins that are twice as large as those that can be attacked by conventional labeling methods.
SAIL proteins are easily prepared from SAIL amino acids by cell-free protein synthesis. This approach ensures that the special labeling patterns of the amino acids are retained in the protein.
Once prepared, NMR structures can be determined by conventional methods. Automation that takes into consideration the properties of the isotopes and their geometric configuration can make structure determinations even more streamlined. ?By exploiting features of the SAIL method, accurate structures can be determined quickly, even for proteins of higher molecular weight.? The time savings and higher accuracy result from a number of factors.
- It is much easier to identify NMR signals from SAIL proteins, because peaks are sharper and NMR spectra are less crowded. ?
- Sharper peaks mean that less time has to be devoted to data collection. ?
- NOESY spectra are less crowded and can be collected at longer mixing times because direct relaxation is slower; this means that more distance constraints can be resolved including those between pairs of protons that are more distant than 5 AE ?
- Because the amino acids are all chiraly labeled, it is unnecessary to make chiral assignments. ?
- All of these factors support more reliable automated analysis. This saves the enormous amounts of time and cost, typically required for a structure determination.
The world’s most remarkable protein NMR system supports rapid data collection and analysis and a low cost/performance ratio.
The World's Fastest Performance
Our system can support the determination of protein structures in two weeks or under. This may represent a time saving by a factor of ten or more.
Automation
Automated structure analysis by SAIL-optimized CYANA software streamlines operations and makes it possible for even inexperienced researchers to determine protein structures.
Highly Accurate Structure Determinations
The method enables highly accurate resolution of critical local structures such as protein active sites.
High Molecular Weight
The SAIL approach extends the molecular weight limit for routine NMR structure determinations, previously at 25 kDa, to 50kDa.
