探讨与生命科学相关专业的化学基础课程为适应新形势的发展需要应该进行的调整与改革。

2003年度的诺贝尔化学奖授予洛克菲勒大学的Roderick MacKinnon博士和约翰斯·霍普金斯大学的Peter Agre博士，以表彰他们在细胞膜水分子通道和离子通道方面所做的开创性工作。本文简介2003年诺贝尔化学奖获得者及其工作。

S-Adenosylhomocysteine hydrolase (AdoHcy hydrolase) crystallizes from solutions containing the intermediate analogue neplanocin A with the analogue bound in its 3'-keto form at the active sites of all of its four subunits and the four tightly bound cofactors in their reduced (NADH) state. The enzyme is in the closed conformation, which corresponds to the structure in which the catalytic chemistry occurs. Examination of the structure in the light of available, very detailed kinetic studies [Porter, D. J., Boyd, F. L. (1991) J. Biol. Chem. 266, 21616-21625. Porter, D. J., Boyd, F. L. (1992) J. Biol. Chem. 267, 3205-3213. Porter, D. J. (1998) J. Biol. Chem. 268, 66-73] suggests elements of the catalytic strategy of AdoHcy hydrolase for acceleration of the reversible conversion of AdoHcy to adenosine (Ado) and homocysteine (Hcy). The enzyme, each subunit of which possesses a substrate-binding domain that in the absence of substrate is in rapid motion relative to the tetrameric core of the enzyme, first binds substrate and ceases motion. Probably concurrently with oxidation of the substrate to its 3'-keto form, the closed active site is "sealed off" from the environment, as indicated by a large (108-9-fold) reduction in the rate of departure of ligands, a feature that prevents exposure of the labile 3'-keto intermediates to the aqueous environment. Elimination of the 5'-substituent (Hcy in the hydrolytic direction, water in the synthetic direction) generates the central intermediate 4',5'-didehydro-5'-deoxy-3'-ketoadenosine. Abortive 3'-reduction of the central intermediate is prevented by a temporary suspension of all or part of the redox catalytic power of the enzyme during the existence of the central intermediate. The abortive reduction is 104-fold slower than the productive reductions at the ends of the catalytic cycle and has a rate constant similar to those of nonenzymic intramolecular model reactions. The mechanism for suspending the redox catalytic power appears to be a conformationally induced increase in the distance across which hydride transfer must occur between cofactor and substrate, the responsible conformational change again being that which "seals" the active site. The crystal structure reveals a well-defined chain of three water molecules leading from the active site to the subunit surface, which may serve as a relay for proton exchange between solvent and active site in the closed form of the enzyme, permitting maintenance of active-ite functional groups in catalytically suitable protonation states.

在探索生命奥秘的过程中，生物无机化学研究由分子层次上升到细胞层次是一个必然的趋势，也是解决实际问题的需要，细胞无机化学研究在细胞生命体系中的无机化学反应和探索无机物对生命过程调节或干预的作用和机理，是探索生命体系复杂性研究的重要部分。细胞是保留完整生命活动特征的最小单位，存在周期、分化和受激等状态的不同。从化学的观点，细胞是一个严密设计的分子有序组装体，为一个多靶分子系统，细胞应答表现为由相关反应组合成的复杂过程。细胞无机化学研究包括无机物种在细胞膜上的结合和随后发生的膜结构和功能改变、跨细胞膜和跨生物组织屏障的转运和细胞代谢、细胞中无机化学反应同细胞信号系统的偶联、无机离子与自由基的相互代谢关系以及细胞-无机物固相的相互作用等方面。本文对当前细胞无机化学研究的重点问题进行了讨论。

无机物的吸收、分配、代谢和排除以及毒性（ADM EöT ox）研究在药物和毒物研究中非常重要。近年来发展的在细胞层次上应用高通量和计算机等技术系统探索药物先导化合物的ADM EöT ox 发展迅速。金属和其它无机化合物的ADM EöT ox 研究在国内外都还是一个新兴的、具有广阔发展前途的跨学科研究领域。本文综述了国内外对于铁和铜以及稀土等金属的化合物的ADM EöT ox 研究结果。提出一些应该开展的工作和有待解决的问题

Lanthanum ion (La3+) has been reported to affect proliferation or apoptosis of different cells. In the present study, La3+ was confirmed to promote both proliferation and apoptosis of NIH 3T3 cells at the same concentrations. La3+ was shown to promote proliferation by helping the cells to pass through the G1/S restriction point and enter S phase, however, the proliferating cells induced by incubation with La3+ eventually underwent apoptosis. The proliferation and apoptosis of NIH 3T3 cells induced by La3+ were well correlated with cell-cycle alterations. La3+ caused the phosphorylation of extracellular signal-regulated kinase (ERK) 1/2; while inhibition of ERK phosphorylation by 2'-amino-3'-methoxyflavone (PD98059) suppressed both proliferation and apoptosis induced by La3+. Based on the above experimental results, we postulated that La3+-promoted proliferation of NIH 3T3 cells could be interconnected with the cell apoptosis, possibly through cell-cycle machinery. Our results thus support the recent hypothesis that proliferation and apoptosis of cell are intrinsically coordinated.

本文首先从试剂分析的观点对免疫分析的原理进行了论述，对抗体作为分析试剂进行了评价并且总结了标记免疫分析的三种方式和四个环节；其次，对免疫分析的现状作了综述，并评述了当代免疫分析的五个热点：基因工程抗体，生物素一亲合素多重标记体系，时间分辨荧光免疫分析，多组分免疫分析和自动化免疫分析；最后，对免疫分析的发展趋势作了讨论。

Binding of La3+ to calmodulin (CaM) and its effects on the complexes of CaM and CaMbinding peptide, polistes mastoparan (Mas), were investigated by nuclear magnetic resonance (NMR) spectroscopy, fluorescence and circular dichroism spectroscopy, and by the fluorescence stopped-flow method. The four binding sites of La3+ on CaM were identified as the same as the binding sites of Ca2+ on CaM through NMR titration of La3+ to uniformly 15N-labeled CaM. La3+ showed a slightly higher affinity to the binding sites on the N-terminal domain of CaM than that to the C-terminal. Large differences between the 1H-15N heteronuclear single quantum coherence (HSQC) spectra of Ca4CaM and La4CaM suggest conformational differences between the two complexes. Fluorescence and CD spectra also exhibited structural differences. In the presence of Ca2+ and La3+, a hybrid complex, Ca2La2CaM, was formed, and the binding of La3+ to the N-terminal domain of CaM seemed preferable over binding to the C-terminal domain. Through fluorescence titration, it was shown that La4CaM and Ca2La2CaM had similar affinities to Mas as Ca4CaM. Fluorescence stopped-flow experiments showed that the dissociation rate of La3+ from the C-terminal domain of CaM was higher than that from the N-terminal. However, in the presence of Mas, the dissociation rate of La3+ decreased and the dissociation processes from both global domains were indistinguishable. In addition, compared with the case of Ca4CaM-Mas, the slower dissociations of Mas from La4CaM-Mas and Ca2La2CaM-Mas complexes indicate that in the presence of La3+, the CaM-Mas complex became kinetically inert. A possible role of La3+ in the Ca2+-CaM-dependent pathway is discussed.

In an effort to design more specific and potent inhibitors of S-adenosylhomocysteine (AdoHcy) hydrolase, we investigated the mechanisms by which 5',5',6',6'-tetradehydro-6'-deoxy-6'-halohomoadenosines (X=C1, Br, I) inactivated this enzyme. The 6'-chloro (a) and 6'-bromo (b) acetylenic nucleoside analogues produced partial (50%) loss of enzyme activity with a concomitant (50%) reduction of E-NAD+ to E-NADH. In addition, Ade and halide ions were released from the inhibitors in amounts suggestive of a process involving enzyme catalysis. AdoHcy hydrolase, which was inactivated with compound a, was shown to contain 2 mol of the inhibitor covalently bound to Lys318 of two subunits of the homotetramer. These data suggest that the enzyme-mediated water addition at the 5'position of compound a or b produces an R-halomethyl ketone intermediate, which is then attacked by a proximal nucleophile (i.e., Lys318) to form the enzyme-inhibitor covalent adduct (lethal event); in a parallel pathway (nonlethal event), addition of water at the 6'position produces an acyl halide, which is released into solution and chemically degrades into Ade, halide ion, and sugar-derived products. In contrast, compound c completely inactivated AdoHcy hydrolase by converting 2 equiv of E-NAD+ to E-NADH and causing the release of 2 equiv of E-NAD+ into solution. Four moles of the inhibitor was shown to be tightly bound to the tetrameric enzyme. These data suggest that compound cinactivates AdoHcy hydrolase by a mechanism similar to the acetylenic analogue of Ado described previously by Parry et al. [(1991) Biochemistry 30, 9988-9997].