Naoyuki Kato

1H NMR studies of the reactions of copper(I) and copper(II) with D- penicillamine and glutathione

Reactions of copper ions with D-penicillamine (PSH) have been monitored by 1H NMR spectroscopy in the presence and absence of glutathione (GSH) under aerobic as well as anaerobic conditions. In D2O solution at pD = 7.4, PSH coordinates to Cu+ to form PS(-)-Cu+ under argon atmosphere as revealed from the broadening of each signal. In the presence of dioxygen, the complex was converted to the well-characterized purple cluster species consisting of Cu+, Cu2+, and PS2-. Addition of GSH into this solution quickly decomposed the cluster by the reduction of Cu2+ to Cu+. The cluster species was, however, reproduced after several hours because of the oxidation of Cu+ back to Cu2+. The solution containing both PSH and GSH formed three possible disulfides, PSSP, GSSG, and PSSG, under aerobic conditions. Addition of Cu+ to this solution again produced the purple cluster through several redox reactions. On the basis of these results, it was concluded that the co-existence of PSH and/or PSSP with Cu+ and/or Cu2+ leads to the formation of the stable cluster species regardless of the presence or absence of the other thiols such as GSH. This must be one of the reasons why PSH works in living cells as an effective drug for the Wilson disease.

The origin of salts in water bodies of the McMurdo Dry Valleys

Lithium distributions in lake and pond waters of the McMurdo Dry Valleys of southern Victoria Land, Antarctica were studied to elucidate the origin of dissolved salts and the evolutionary history of the lakes and ponds. The Ef Li [(Li/Cl)sample/(Li/Cl)seawater] values of the bottom waters in Lakes Bonney and Fryxell were higher than unity (Ef Li =4–7), indicating that the salts originated from sea salts (probably relict seawater) and have been subsequently modified by the contribution of meltwaters containing atmospheric fallout and/or rock and soil weathering products. In contrast, extremely high Li concentrations with high Ef Li values in the Don Juan Pond water (Ef Li = 180) and the bottom waters of Lake Vanda (Ef Li = 40) suggest that the salts originated from deep groundwaters influenced mainly by saline water-rock interactions, as supported by the dissolution experiments of granite in NaCl solution. The low Li concentrations of pond waters with high Ef Li values in the Labyrinth indicate that the salts are derived from atmospheric fallout. The decrease of the Ef Li values with the increase of Cl concentrations can be explained by the repeated cycles of the migration of Li into the ice phase and subsequent ablation of surface ice, as indicated by seawater freezing experiments.

Paleoenvironmental changes in the Eurasian continent interior inferred from chemical elements in sediment cores (BDP96/1, BDP96/2) from Lake Baikal

Publisher Summary This chapter presents a study to estimate the paleoenvironmental changes in the Eurasian continent interior during the past 5.2 million years (My) from the levels of inorganic chemical elements in the B DP96/1 core, and to examine the relative contribution of the frequency of precession, obliquity, and eccentricity by spectral analysis of K distribution in the BDP96/2 core. The chemical elements in sediment cores (BDP96/1, BDP96/2) are studied and the terrigenous element content (A1, Ti, and K, etc.) is inversely correlated with diatom abundance, which is a proxy for paleoclimate change. Principal component analysis of data sets for 28 element/aluminum weight ratios in the BDP96/1 core showed that the first principal component scores increased abruptly at 3.4 Ma. The inorganic element content of the BDP96/1 core indicated significant climate change at 2.5 Ma (onset of Northern Hemisphere cooling) and at 3.5 Ma (onset of the aridification of Asia) in the Eurasian continent interior. Spectral analysis of K distribution in the BDP96/2 core showed that the relative variance of the frequency of eccentricity increased from 2.5 Ma to the present. The contributions of frequency of precession and obliquity in the Eurasian continent interior are much greater than those of marine climate records (SPECMAP).

Paleoenvironmental Changes during the Last 12 Million Years in the Eurasian Continental Interior Estimated by Chemical Elements in Sediment Cores (BDP-96 and BDP-98) from Lake Baikal

The content of 29 chemical elements (Na, K, Mg, Ca, Al, Fe, Li, Be, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, Ge, As, Rb, Sr, Mo, Cs, Ba, W, Pb, Th, and U) in 589 subsamples of BD-P96 cores and 703 subsamples of BDP-98 cores from the Academician Ridge of Lake Baikal were determined using inductively coupled plasma-mass spectromety (ICP-MS) in order to estimate paleoenvironmental changes during the last 12 million years in the Eurasian continental interior. The content of terrigenous elements (Na, K, Mg, Ca, Al, Ti, etc.) increased gradually from about 6 Ma BP to the present, with repeated major fluctuations after 3.6 Ma BP, indicating a significant climate change at 3.6Ma BP in the Eurasian continental interior. The abrupt change may be mainly associated with the uplift of the Tibetan plateau and Himalayas. This result corresponds with the rapid increase in the eolian dust accumulation rate in the central north Pacific sediment core (Rea et al. 1998). The data from BDP98 cores indicated that some big changes in the sources of chemical elements occurred at about 7 Ma BP, when the sedimentation rate in the core suddenly increased. We also estimated from the chemical index of alteration (CIA) that the variation in the climate from 8 to 12 Ma BP was small, and the rapid climate change started at 3.6 Ma BP.