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.
The interaction of CO2 and CO with an alkali carbonate carbon system studied by in-situ Fourier Transform infrared spectroscopy
Abstract In-situ Fourier Transform infrared (FT-i.r.) measurements were used to study the alkali carbonate catalysed gasification of an activated carbon, Norit RX Extra. After impregnation with M 2 CO 3 ( M = Cs , K ) alkali bicarbonate and hydrated carbonate are present on the carbon. Also, some bands are visible which are tentatively assigned to CO 2 adsorbed on an electron donor centre on the alkali carbonate carbon sample. Upon heating to 473 K, the potassium bicarbonate is converted to anhydrous carbonate. Caesium carbonate behaves analogously, but is more hygroscopic. At 473 K it is present partly as bicarbonate and partly as species which do not show infrared bands. Upon heating to 773 K, part of the potassium carbonate and all the caesium carbonate decompose to a species active for gasification. The interaction of alkali carbonate carbon samples with CO 2 , in particular above 773 K, leads to formation of C(O) complexes, with an infrared band around 1100 cm −1 . The intensity of this band does not decrease in a CO atmosphere. It is concluded that these C(O) complexes are not the active sites as proposed in the two step gasification mechanism, but relatively stable carbon oxygen complexes present on the carbon during gasification.
Stereoselective disposition of ibuprofen enantiomers in infants.
The pharmacokinetics of the enantiomers of ibuprofen were investigated after oral administration of a single 7.6 +/- 0.3 mg kg-1 dose of the racemate in 11 infants. Mean (+/- s.d.) half-lives were 1.6 +/- 0.5 h for S(+) and 1.5 +/- 0.5 h for R(-) and mean (+/- s.d.) AUC values were 31.5 +/- 14.3 mg l-1 h for S(+) and 36.6 +/- 13.8 mg l-1 h for R(-). Since plasma concentrations of the active S(+)-isomer were lower than those reported in adults, a higher dosage might be required in infants.