Avance II – 500 MHz

This spectrometer is suitable for metabolomics and in vivo NMR studies but structural analysis of small molecules and low molecular weight proteins as well as magic angle spinning NMR spectroscopy (HRMAS-NMR) can also be performed.

To accomplish these studies there are several probe-heads available: two 10 mm QNP C/N/P probe-heads for in vivo NMR experiments, two probe-heads specific for metabolomics studies, selective for ¹³C (DUAL 5 mm) and selective for ³¹P (SEXP 5 mm); two probe-heads for in vivo studies of transport processes coupled with the transport of ²³Na ion (SEXNa 10 mm) and phosphorylated or fluorinated compounds (TXO F/P 10 mm); a 5 mm BBI-xyz high-resolution probe-head for 1D/2D homo- and heteronuclear structural studies, equipped with broadband decoupling of X nuclei (range from ³¹P to ¹⁰⁹Ag) and XYZ-axis pulsed field gradients; and a 5 mm QXI-z C/N/P probe-head and a 5 mm TXI-z C/N probe-heads for DNA and protein studies, respectively.

In its role as a HRMAS-NMR spectrometer, the AvanceII 500 is suitable for studies of liquid suspensions, semi-solid and solid samples of either biological or synthetic origin (for instance: conventional very small volume liquid samples, lipids, polymeric gels, biological tissues, plants, food samples, resins, polymers, etc.).

Description and history of the equipment:

The spectrometer was acquired by the Instituto de Tecnologia Quí­mica e Biológica in 1989. At the time of installation the spectrometer was equipped with an AMX500 console, which was updated to a DRX500 double bay console in 1995. In June 2007 a new and more extensive update was performed comprising not only a new console (a double bay AVANCE II) but also a new pre-amplifier and cryoshim system. This spectrometer, equipped with a Ultra-Shielded-Plus 500 MHz magnet (since 2010), 54 mm diameter standard bore, is controlled via Topspin V.2.1 software installed in a PC with the LINUX operating system. The 5 Gauss magnetic field safety line is described by an ellipsoid with a horizontal and vertical radius of 0.6 m and 1.2 m apart from the magnetic center, respectively.

Two systems are available for low temperature operation:

1. BCU-05 - a nitrogen gas cooling system (exit gas temperature of -20ºC) allowing working temperatures down to 0ºC (approximately);
2. A nitrogen gas cooling system operating by evaporation of liquid nitrogen allowing working temperatures down to -120ºC.

Table of sensitivities (signal to noise ratios) for probe-heads:

QXI-z H-C/N/P

The QXI-z H-C/N/P-D (5 mm) is a probe-head with inverse detection (optimized for ¹H observing), designed to operate at four fixed frequencies (¹H, ¹³C, ¹⁵N and ³¹P), with pulse-field gradients along Z axis and automatically tunable. This probe-head allows the acquisition of multi-dimensional triple resonance spectra from triple-labelled protein samples as well as less complex data from double- single- or non-labelled samples. In addition, the presence of a ³¹P channel allows the acquisition of multi-dimensional correlation data from phosphorylated compounds containing samples.

It is also possible to perform D decoupling using the deuterium channel from the lock system, together with the other three specific nuclei, allowing the decoupling up to four nuclei in only one pulse sequence.

Minimum sample volume: 500 ul
Working temperature range: +150 to -150ºC
Purchase date: 2006

TXI-z H-C/N

The TXI-z H-C/N-D (5 mm) is a probe-head with inverse detection (optimized for ¹H observing), designed to operate at three fixed frequencies (¹H, ¹³C and ¹⁵N) and with pulse-field gradients along Z axis. This probe-head allows the acquisition of multi-dimensional double resonance spectra from double-labelled protein samples as well as less complex data from single- or non-labelled samples.

It is also possible to perform D decoupling using the deuterium channel from the lock system, together with the other two specific nuclei, allowing the decoupling up to three nuclei in only one pulse sequence.

Minimum sample volume: 500 ul
Working temperature range: +150 to -150ºC
Purchase date: 2007

BBI-xyz H-X

The BBI-xyz H-X-D (5 mm) is a probe-head with inverse detection (optimized for ¹H observing), wide range frequency decoupling possibility (from ³¹P to ¹⁰⁹Ag) and with pulse-field gradients along XYZ axis. It can be used for structural studies applied to small molecules and low molecular weight proteins and based on homonuclear (e.g., COSY, NOESY, TOCSY, etc.) or heteronuclear (e.g., HSQC, HMQC, HMBC, etc.) correlations and their multiple combined forms (HSQC-TOCSY, HSQC-NOESY, etc.). Also, this probe-head is frequently used for ¹H-NMR experiments requiring heteronuclear broadband decoupling and/or solvent suppression.

Minimum sample volume: 500 ul

Working temperature range: +80 a -50ºC
Purchase date: 1998

DUAL AND SEXP SELECTIVE

DUAL C-H-D (5 mm) and SEX P-H-D (5 mm) are selective probe-heads used for direct observation of Carbon or Phosphorus, respectively. Both accessories can perform proton decoupling if required.

Being optimized for only one nucleus, they are very useful for low concentration sample analysis as the ones obtained from metabolomics studies.

Minimum sample volume: 500 ul
Working temperature range: +180 a -150ºC
Purchase date (DUAL): 1994
Purchase date (SEXP): 2002

QNP C/N/P-H

The two QNP C/N/P-H-D (10 mm) are quadruple probe-heads designed for direct observation of three fixed X nuclei frequencies (¹³C, ¹⁵N and ³¹P) and ¹H decoupling if applicable. The possibility to accommodate 10 mm NMR tubes allows performing in vivo NMR studies using cellular suspensions, small organs, etc. The probe-heads are equipped with a pneumatic switching accessory for automatic changing of observed NMR frequency.

Minimum sample volume: 2.5 ml
Working temperature range: +150 a -130ºC
Purchase date: 1993 and 2007

SEXNA E TXO F/P SELECTIVE

SEX Na-H-D (10 mm) and TXO F/P-H-D (10 mm) are selective probe-heads used for direct observation of Sodium, Fluorine or Phosphorus.

Both probe-heads were build-up especially for in vivo NMR transport studies.

Minimum sample volume: 2.5 ml
Working temperature range: +150 a -130ºC
Purchase date (SEXNa): 1991
Purchase date (TXO F/P): 1997

HR MAS TRIPLE C/P-H

The HR MAS Triple C/P-H-D (4 mm) is a high-resolution triple resonance probe-head with Magic Angle Spinning rotation (max. rate: 15 kHz), designed for ¹H, ¹³C and ³¹P direct observation and/or decoupling, and with pulse-field gradients along Z axis. High-resolution NMR spectra of semi-solid (e.g.: paste, gels, resins, etc.) or liquid samples, from any origin (biological, organic or inorganic), can be obtained using this probe-head.

Maximum speed rotation: 15 kHz
Maximum sample volume: 50 ul

Working temperature range: +70 a -20ºC
Purchase date: 2007