DEVELOPMENT OF A BIOSUPRAMOLECULAR NMR SYSTEM WITH A SUPERCONDUCTING MAGNET

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A multinuclear observation system was built into our AM-400 NMR spectrometer (Bruker). Then, a solid-state probe head for deuterium NMR was developed. The quadrupole echo pulse sequence was used for the measurements. At first, a solenoid coil was built in a probe head, originally used for solution NMR. The 90ﾟ pulse was 12mus. The circuits of the probe head and matching box were simplified. After the modification, the 90ﾟ pulse became to be about 4mus. Thus, we have established the solid-state NMR system, which can be used for the start point of this project. phospholipids specifically deuterated in the glycerol backbone were obtained from E. coli cells cultured in the presence of perdeuterated glycerol.Since biological samples contain water, the sample tube should be held vertically. Although the power is very efficient in the solenoid coil, the sample tube is kept in horizontal. So we decided to change the coil design. A saddle type coil was attached on the surface of a glass tube with 5 mmphi, which was put in the vertical direction. The 8-turn coil fits to 0.94 cm^3 sample volume. The 90ﾟ pulse of this coil was 7.8mus. In order to get more power, a high power amplifier was connected. However, arching took place in the probe head on the use of this amplifier. Since the bore size of our magnet is narrow, the probe is not enough to avoid the arching. The probe was examined without the amplifier. By using 60 mg deuterated phospholipids, a ^2H-NMR spectrum in good quality was obtained. The spin-lattice relaxation time was measured using the inversion-recovery method. Whole region of the power pattern spectrum was inverted by the 180ﾟ pulse. These results show that this coil can be used for the investigation of the phospholipid bilayers. Thus, we have succeeded in establishing a solid-state NMR system suitable for biomembrane studies.