Electron Spin Resonance of Adenosine Triphosphate
IT has been suggested that in adenosine triphosphate (ATP) the phosphate chain and the adenine are linked by the pentose, so that the two terminal phosphates touch the two nitrogen atoms at positions 6 and 7 in the adenine ring1; and that, since triphosphate compounds might be electron acceptors and adenine is a good electron donor, the adenine group might donate an electron to the triphosphate group2. I. Isenberg and A. Szent-Györgyi2 obtained an electron spin resonance signal from ATP (di-sodium salt) which they attributed to internal charge transfer between the adenine and the triphosphate. They also suggested that there was a possibility that the signal could be due to a transition metal impurity in the form of a transition metal – ATP complex. In view of the great importance of ATP in living processes, we have re-examined the electron spin resonance of this compound to decide between these possibilities.
Electron spin resonance and its applications
The method of electron spin resonance spectroscopy for studying free radicals and related materials is outlined and the basic parts of the theory are given. Some typical spectrometers are indicated and details are given of the arrangement of samples of different kinds. Three systems are discussed in some detail, as examples, namely the spectrum of a free radical in irradiated alanine, the semiquinone spectrum in solution and the haemoglobin crystal structure problem. Reference is made to applications in biology and related fields; subjects of special importance include radiobiology, photosynthesis, enzymic oxidation and nucleic acid complexes.
The MR-TOF-MS isobar separator for the TITAN facility at TRIUMF
At TRIUMF’s Ion Trap for Atomic and Nuclear Science (TITAN) a multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS) will extend TITAN’s capabilities and facilitate mass measurements and in-trap decay spectroscopy of exotic nuclei that so far have not been possible due to strong isobaric contamination. This MR-TOF-MS will also enable mass measurements of very short-lived nuclides (half-life > 1 ms) that are produced in very low quantities (a few detected ions overall). In order to allow the installation of an MR-TOF-MS in the restricted space on the platform, on which the TITAN facility is located, novel mass spectrometric methods have been developed. Transport, cooling and distribution of the ions inside the device is done using a buffer gas-filled RFQ-based ion beam switchyard. Mass selection is achieved using a dynamic retrapping technique after time-of-flight analysis in an electrostatic isochronous reflector system. Only due to the combination of these novel methods the realization of an MR-TOF-MS based isobar separator at TITAN has become possible. The device has been built, commissioned off-line and is currently under installation at TITAN.