重组人粒细胞刺激因子化学稳定性的影响因素探讨

重组人粒细胞刺激因子是一种非常重要的重组蛋白质药物,它容易发生蛋白质氧化。采用反相色谱法测定37℃加速试验和4℃长期稳定性试验中该产品的纯度变化,研究其保藏过程中的化学稳定性。考察了添加氧化剂和还原剂对产品的短期和长期稳定性作用,结果表明所有氧化剂包括过氧化氢和亚硝酸盐都具有较强的浓度效应而还原剂具有较强的pH依赖性。当亚硝酸盐浓度大于0.1 ppm时,具有明显的氧化作用。进一步考察了不同包装材料和过渡态金属离子对化学稳定性的作用。安瓿瓶火焰融封时会导致过渡态金属离子的溶出,结果表明亚铁离子催化活性最强,在0.05 ppm浓度下就具有明显的氧化作用。加入抗氧化剂L-Met能在一定程度上降低长期保藏过程中化学不稳定性,而添加金属螯合剂EDTA二钠能够明显提高该重组蛋白药物的化学稳定性。

酶催化的动态动力学拆分和去消旋化反应的研究进展

最近,在外消旋化合物的动态动力学拆分以及去消旋化反应方面,新型催化剂的发现以及反应条件的优化都得到了很大的发展。一些特殊功能团使得它们的化合物可以发生动态动力学拆分或是去消旋反应,如仲醇、α-氨基酸、胺及羧酸。在催化反应过程中,一般都是对映体选择性酶与化学试剂的相结合,化学试剂一般常用于催化非活性对映体发生去消旋反应或是回收去消旋化过程中的中间体。在一些动态动力学拆分中,消旋酶还可以催化对映异构体之间发生互变。

Vibrational and Structural Dynamics of Mn（CO）sBr and Re（CO）sBr Examined Using Nonlinear Infrared Spectroscopy

Vibrational and structural dynamics of two transition metal carbonyl complexes, Mn（CO）5Br and Re（CO）5Br were examined in DMSO, using ultrafast infrared pump-probe spectroscopy, steady-state linear infrared spectroscopy and quantum chemistry computations. Two car- bonyl stretching vibrational modes （a low-frequency A1 mode and two high-frequency degenerate E modes） were used as vibrational probes. Central metal effect on the CO bond order and force constant was responsible for a larger E-A1 frequency separation and a generally more red-shifted E and A1 peaks in the Re complex than in the Mn complex. A generally broader spectral width for the A1 mode than the E mode is believed to be partially due to vibrational lifetime effect. Vibrational mode-dependent diagonal anharmonicity was observed in transient infrared spectra, with a generally smaller anharmonicity found for the E mode in both the Mn and Re complexes.

The oceanic cycles of the transition metals and their isotopes

The stable isotope systems of the transition metals potentially provide constraints on the current and past operation of the biological pump,and on the state of ocean redox in Earth history.Here we focus on two exemplar metals,nickel(Ni)and zinc(Zn).The oceanic dissolved pool of both elements is isotopically heavier than the known inputs,implying an output with light isotope compositions.The modern oceanic cycle of both these elements is dominated by biological uptake into photosynthesised organic matter and output to sediment.It is increasingly clear,however,that such uptake is associated with only very minor isotope fractionation.We suggest that the isotopic balance is instead closed by the sequestration of light isotopes to sulphide in anoxic and organic-rich sediments,so that it is ocean chemistry that controls these isotope systems,and suggesting a different but equally interesting array of questions in Earth history that can be addressed with these systems.

Non-noble metal single-atom catalyst of Co_(1)/MXene(Mo_(2)CS_(2))for CO oxidation

MXene is a variety of new two-dimensional(2D)materials with early transition metal carbides,nitrides,and carbonitrides.Quantum chemical studies have been carried out on the geometries,electronic structures,stability and catalytic properties of a non-noble metal single-atom catalyst(SAC)with single Co atom anchored on MXene materials of Mo_(2)CS_(2).The Co adatom anchored on top of the Mo atom of this MXene is found to be rather stable,and this SAC is appropriate for CO oxidation.The charge transfers from the surface to the adsorbed CO and O2 play a significant role in the activation of these molecules on Co_(1)/Mo_(2)CS_(2).With this catalyst,the Eley-Rideal(ER),Langmuir-Hinshelwood(LH),and Termolecular Eley-Rideal(TER)mechanisms are explored for CO oxidation.We find that,while all the three mechanisms are feasible at low temperature,Co_(1)/Mo_(2)CS_(2) possesses higher catalytic activity for CO oxidation through the TER mechanism that features an intriguing OC(OO)CO intermediate(IM)adsorbed on Co single atom.The calculated activation energy barriers of the rate-limiting step are 0.67 eV(TER),0.78 eV(LH)and 0.88 eV(ER),respectively.The present study illustrates that it is promising to develop and design low-cost,non-noble metal SACs using MXene types of 2D materials.

Tailoring the spin state of active sites in amorphous transition metal sulfides topromoteoxygen electrocatalysis

Spin regulation of active sites is sparking much interest in boosting oxygen electrocatalytic performance.However,in amorphous electrocatalysts,the design principle of spin regulation to promote catalytic activity remains unclear.Herein,we synthesized a series of heteroatom-doped amorphous transition metal sulfides with regulated spin states using a one-step hydrothermal process.Especially in Modoped CoS,the spin state of Co^(2+)was successfully modulated to the low-spin state,which could optimize the adsorption free energy of various intermediates,improving the oxygen reduction reaction kinetics.The fabricated Zn-air batteries(ZABs)delivered good cycle stability(over 100 h).The large ZAB(100 cm^(2))exhibited a high discharge voltage(1.25 V under 0.5 A)and a superior overall mass-energy density(93 W h kg^(−1)),which illuminated a 2.5-m light-emitting-diode ribbon for over seven days.This work provides new insight into the mechanism of engineering spin states in amorphous materials for oxygen electrocatalysis.

New cyclometalated transition-metal based photosensitizers for singlet oxygen generation and photodynamic therapy

The aim of this review article is to introduce recent studies on an emergent class of singlet oxygen photosensitizers of potential applications to the photodynamic therapy,with a primary focus on the cyclometalated transition-metal complexes.Singlet oxygen photosensitization performances of various cyclometalated Ir and Pt scaffolds are reviewed,and the general photophysical properties of relevant systems and the mechanisms of singlet oxygen production via photo-sensitization are also briefly discussed.Thus far,investigations of singlet oxygen sensitization by such Ir and Pt complexes are mainly carried out in organic solvents and under non-physiological conditions,while some research efforts have been made at examining the feasibility of applying pertinent cyclometalated complexes to photodynamic therapy.