pH effect of· OH radical induced oxidation of phosphoryl- methionine in aqueous solution

Conclusion The results of pulse radiolytical research on the · OH radical-induced oxidation of NDM in aqueous solution demonstrate that pH value has a great influence on the radiolytical mechanism of NDM. At low pH value, the product is mainly stabilization of the oxidizing sulfur centre in the three-electron-bonded cation radical NDM₂ ·⁺ [S]; with the increase of pH value, NDM₂ ·⁺ [S] gradually decays to become the reducing α-amino radical which was verified by the chemical method and whose yield was also calculated. Compared with Met₂ ·⁺ [S] produced by the · OH radical-induced oxidation in aqueous solution [1], the stability of NDM₂·⁺ [S] increases and the yield of α-amino radical decreases. This suggests that the introduction of phosphoryl group has a coordinating effect on the radioprotection of methionine to biological systems, and provides the essentially theoretical foundation for the thorough clarification of the reversible phosphorylation of proteins.     

Studies on the reaction between Laccase ando-methoxyphenol by microcalorimetry

The reaction between Laccase ando-methoxyphenol have been studied by LKB-2107 batch microcalorimetry system. Thermodynamic parameters Δ _r H _m , ΔG _o , ΔG _T ^≠ and kinetic parameters (K _m ,k ₂) have been determined. The process of the reaction has been analyzed from changes in energy by using the transition state theory. Two methods for enhancing catalytic power of Laccase are proposed. The results shown that formation of an enzyme-substrate complex is “anticatalytic”. The enter and sole source of catalytic power is the stabilization of transition state; reactant-state interactions are by nature inhibitory and only waste catalytic power. Supported by the National Natural Science Foundation of China Wang Tianzhi: born in 1968. Ph D     

A method of quantitatively calculating amount of allochthonous organic carbon in lake sediments

Conclusion The lake sediments have registered the information of palaeoclimate and palaeoenvironment in the lake itself and the regional scale. This also leads to a complexity in study of the palaeolimnology by all kinds of proxies. How to purify these proxies to indicate the palaeoclimate has become a problem to be solved. Most of the proxies can qualitively identify the percentage of allochthonous and autochthonous organic components, e.g. δ¹³c_org CD/TC. The model introduced in this note has provided a method of quantitatively calculating the amount of allochthonous organic carbon. As for determination of regulating parameters, i.e. A1 and As, further work is still in need.