药用植物对蘑菇酪氨酸酶激活作用的研究

以采集自厦门周边地区的15种药用植物为材料,研究药用植物的提取分离物对蘑菇酪氨酸酶的效应.结果表明:绞股蓝乙醇提取物、金毛狗脊乙醇提取物、爵床乙醇提取物、大青乙醇提取物、溪黄草石油醚和乙酸乙酯萃取物、千里光乙酸乙酯和正丁醇萃取物、翅柄马兰石油醚和乙酸乙酯萃取物,以及金酸枣正丁醇萃取物具有轻微激活作用,激活率分别为3.4%、20%、20%、40%、38.3%、27.6%、36%、42%、20%、50%和30%;扭序花正丁醇萃取物、野慈姑乙醇提取物、毛麝香乙醇提取物、使君子乙酸乙酯和正丁醇萃取物、冬青氯仿萃取物具有较好的激活作用,激活率分别为55%、60%、68.2%、62%、60%和80%;而金酸枣石油醚萃取物、冬青乙酸乙酯萃取物、斑鸠菊正丁醇萃取物和白面风乙醇提取物具有明显的激活作用,激活率分别为120%、150%、170%、和327%.动力学分析激活机理主要有混合性、竞争性和反竞争性3种激活类型

Electrochemical Gating Single-Molecule Circuits with Parallel Paths

# These authors contributed equally to this work.电化学门控已成为一种可行且高效调节单分子电导的方法。在本研究中,我们证实了具有两个平行苯环的单分子电路中电子传输可以通过电化学门控控制。首先,我们利用STM-BJ技术以金为电极构筑了具有两条平行路径的单分子结。与单条路径的单分子结相比,两条路径的分子结由于具有增强性量子干涉效应,具有2.82倍的电导值。进一步地,我们利用电化学门控对具有两个平行苯环的单分结的电导进行调控,获得了333%·V-1调节比。结合DFT计算,发现在E=EF附近的V形透射系数谱图导致了实验观测的电导门控行为。本研究揭示了具有平行路径的单分子电路的电化学门控行为,并为设计高性能分子器件的分子材料提供了新的途径。通讯作者:周小顺E-mail:[email protected]:Xiao-ShunZhouE-mail:[email protected].浙江师范大学物理化学研究所,先进催化材料教育部重点实验室,浙江 金华 3210042.上海大学物理系,上海 2004441. Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004, Zhejiang, China2. Department of Physics, Shanghai University, Shanghai 200444, Chin

A specific bioconjugation of protein lysine residues and N-terminal via phthalimidine formation and a fluorogenic probe for 5-hydroxylysine

Chemical protein modification has been used to monitor cellular events and to modify proteins. These modifications are achieved by bioconjugation, which covalently attach a chemical molecule onto the protein. These protein modifications include PEGylation, antibody-drug conjugation, fluorescent labeling, etc. Despite the vast range of applications of chemical protein modifications, scientists are facing many challenges in controlling the reactivity and selectivity of the modification. Native protein modification requires a chemoselective reaction under the physiological condition that preferentially reacts at one specific amino acid over the others in order to control the degree of modifications. Lysine residues are highly solvent accessed, with a good nucleophilic side chain functionality for chemical modification. In this thesis, a new chemical strategy using ortho-phthaldialdehyde (OPA), which is highly selective, stable, easy to manipulate, and has high reactivity towards lysine is reported. The reaction of OPA and amines in organic solvents forming phthalimidines is well documented. However, such a reaction under the physiological condition with which to label and modify native proteins has not been explored previously. With a peptide model, we observed rapid lysine modification with OPA via phthalimidine formation in physiological buffers such as PBS, tricine, HEPES and as well as basic borate buffer. To demonstrate the vast applications, different functionalized OPA derivatives were chemically synthesized, which included different sizes of PEGs, alkyne and carboxylic acid group. These derivatives were tested with model peptides. In the presence of other nucleophilic amino acid residues, such as serine, threonine, tyrosine and histidine, OPA selectively modified lysine, while classical NHS esters showed non-specific modifications. OPA also showed better modification efficiency, with a higher second order rate constant (7.49 M^(-1) s^(-1)) compared to that of NHS (1.27 M^(-1) s^(-1)-). Proteins including cytochrome c, lysozyme, ribonuclease A, and myoglobin were successfully modified with OPA derivatives. Combining with an alkyne group, a fully functional heterobifunctional linker was synthesized and applied to bovine serum albumin (BSA). Protein immobilization on solid support was also demonstrated. PEGylation of L-asparaginase using OPA protocol showed increased stability against proteolytic degradation while maintaining high degree of activity. In the next section, we turned our attention to the detection of 5-hydroxylysines. 5-hydroxylysines is naturally synthesized through a posttranslational modification of lysine. Although hydroxylysines are most widely known as a component of collagen, they also exist in “noncollagen” proteins such as mannose binding proteins, type I and II macrophage scavenger receptors. It is very likely that lysyl-5-hydroxylation as post-translational modification frequently happens in many other proteins. Thus, the biological significance of lysyl-5-hydroxylation requires extensive studies. Recently, our group has developed a new ligation strategy, named serine/threonine ligation (STL), which uses an N-terminal serine or threonine to mediate a chemoselective peptide ligation. 5,6-hydroxylamino group of 5- hydroxylysine has structural similarity with N-terminal serine and threonine. Thus, we designed and synthesized an umbelliferone based-fluorogenic probe, which could react with 5-hydroxylysine containing peptide through STL chemistry, generating a fluorescent product. The probe showed very high selectivity and could detect as low as 0.01 mM of hydroxylysine containing peptides in the system.published_or_final_versionChemistryDoctoralDoctor of Philosoph

面向手机直连的星载相控阵：关键技术与未来展望

手机直连卫星通信传输距离远、链路损耗大的特点，对星载相控阵的能力提出了新要求。通过分析手机直连卫星场景的实际需求，概述了不同波束成形架构的优劣，提出了合适的波束成形架构选择策略，探讨了频分双工体制下双频共口径圆极化天线阵设计，阐述了星载相控阵堆叠集成架构和芯片关键工艺技术。给出了在手机直连卫星场景下，星载相控阵未来的发展方向和关键技术路径