Temperature dependence of positron lifetimes in carbonic anhydrase

Abstract

references cited therein; (d) H. Basch, Theor. Chim. Acta, 28, 151 (1973). We thank Professor C. Trindle (University of Virginia) for this reference.(3) For reviews, see (a) G. L. Closs in Top. Stereochem., 3, 193 (1968); (b) P.

Positronium Physics and Biomedical Applications

“…However, he focused his attention on the order and arrangement of tissue water and not on muscle structure. Further studies on complex biological systems like biological membranes or proteins moved positronium research towards structural biology and showed that this approach was efficient in the study of biological reactions (such as electron transfer (Jean and Ache, 1977)), phase transition of lipids (Chow et al, 1981;Jean and Hancock, 1982;Stinson et al, 1980) macromolecule structure (Handel et al, 1976), hydratation (Akiyama et al, 2007Gregory et al, 1992;Handel et al, 1980) and porosity (Chamerski et al, 2017;Pamula et al, 2006) of biological samples. Nowadays, after many years of focused research, PALS appears to be a promising technique in the investigation of the structure of macromolecules (Chen et al, 2012) and clinical samples (Avachat et al, 2022;Moskal et al, 2021a,b;Zgardzinska et al, 2020).…”

“…The first applications of positronium properties in the life sciences were made by Handel in late 70s (Handel et al, 1976(Handel et al, , 1980. Having in mind that positron annihilation lifetime is sensitive to changes in free volume caused by pressure (which is rarely studied in biological systems) or by thermal expansion in the same phase, he showed significant changes in positronium lifetime during phase transitions of biological systems.…”

“…Covalent bonds between carbon atoms in organic molecules hold structure (architecture) of biological macromolecules contributing to the creation of free volumes (so-called molecular voids). Such a molecular structure (here we call it nanostructure (Pethrick, 1997)) is changing dynamically with temperature (Handel et al, 1976;Sane et al, 2009;Stinson et al, 1980), and is stabilized by hydrogen bonds (Gregory et al, 1992;Handel et al, 1980;Kilburn et al, 2006). The specific feature of the shortening of τ o−Ps in the pick-off process has been proposed for prob-ing sub-nanometer-sized local free volumes in solid materials and organic polymers to assess the size and nature of chemical environment (Dlubek et al, 2000;Pethrick, 1997).…”

Macromolecular conformation in solution. Study of carbonic anhydrase by the positron annihilation technique

“…The application of the positron annihilation technique to biophysical problems is rather recent (cf. Handel et al, 1976;McMahon et al, 1979;Graf et al, 1979). Here we investigate our suggestion that the positron is a sensitive probe of protein conformation.…”

Ortho-positronium Quenching in Benzene Solutions of Iron(III) Dithiocarbamates

“…The fivecoordinate halogenobis(diethyldithiocarbamato) iron (III) complexes, which are paramagnetic and hardly reducible, were also tested for the effect on the o-Ps quenching. Unlike the six-coordinate iron(III) dithiocarbamates, they only slightly affected the o-Ps lifetime, indicating that the spin-conversion process of o-Ps quenching is much less important than the oxidation process.Positronium, which is the bound state of a positron with an electron, has attracted increasing attention from many researchers and the positron annihilation as a nuclear probe has been widely applied to the study of the chemical [ 1 -6 ], miceller [ 7 -9 ], and biological systems [10][11][12]. The variation of the intensity of the long-lived component of positronium against the inhibitor concentration in systems of organic solutions has recently been successfully explained in terms of the spur model [13][14][15].…”