模块化、平台化的智能用电信息采集终端设计

为了解决当前用电信息采集终端采集能力不足、通用性不高及可扩展性不强等问题,提出了一种模块化、平台化的智能用电信息采集终端设计方案.该采集终端以操作系统平台为基础,以独立应用APP与模块化硬件接口为支撑,打造终端软硬件平台.测试结果表明,基于该方案的采集终端采集频率更高、数据量更大,各硬件模块和独立应用APP均具备独立设...     

多光谱遥感影像的SAM-SID混合分类技术研究

以SPOT 5多光谱影像为数据源,通过与SAM、SID以及常规的最大似然法(ML)和最小距离法(MD)的对比,研究了基于SAM-SID混合法的土地覆盖多光谱遥感分类技术。研究结果显示,相比于SAM和SID,SID(TAN)和SID(SIN)两个SAM-SID混合参量对多光谱影像上地物识别的能力更强,尤以SID(SIN)的识别能力最强;基于SID(SIN)的多光谱遥感分类验证精度达78.94%,不但明显高于SAM和SID法,而且也高于常规的MD和ML监督分类方法。这说明SAM-SID混合分类方法不但适用于高光谱遥感分类,同时在多光谱遥感分类中也有很强的适用性。     

地铁AFC系统中的射频卡读写器设计

针对地铁自动售检票（AFC）系统中射频卡读写器通信接口单一、无线接入等问题,设计一种基于ARM9和MFRC531的高性能射频卡（非接触式IC卡）读写器,可以同时支持RS232、RS422、USB和GPRS通信方式,具有通信接口多样、操作速度快、可靠性高以及使用方便等特点。该读写器可快速进行非接触式票卡识别、读写并正确显示和报警,可以方便地安装在地铁进出闸机、售票机及城市“一卡通”充值机上,具有良好的应用前景。     

DNA-Methyltransferasen und AdoMet-Analoga als Werkzeuge für die Molekularbiologie und Biotechnologie

For a long time, DNA methyltransferases were of particular interest for basic molecular biology research since they regulate important processes in both prokaryotes and eukaryotes. Since the development of synthetic analogs of the cofactor S-adenosyl-L-methionine, it has been possible to transfer not only methyl groups but also numerous functional groups to DNA in a sequence-specific manner. Due to their structure, some DNA methyltransferases exhibit remarkable promiscuity with respect to the cofactor, so that DNA labeling can succeed with good efficiency. In this review article, we summarize the important developments in this field and discuss interesting current and potential applications in molecular biology and biotechnology.     

Visible-Light Removable Photocaging Groups Accepted by MjMAT Variant: Structural Basis and Compatibility with DNA and RNA Methyltransferases

Methylation and demethylation of DNA, RNA and proteins constitutes a major regulatory mechanism in epigenetic processes. Investigations would benefit from the ability to install photo-cleavable groups at methyltransferase target sites that block interactions with reader proteins until removed by non-damaging light in the visible spectrum. Engineered methionine adenosyltransferases (MATs) have been exploited in cascade reactions with methyltransferases (MTases) to modify biomolecules with non-natural groups, including first evidence for accepting photo-cleavable groups. We show that an engineered MAT from Methanocaldococcus jannaschii (PC-MjMAT) is 308-fold more efficient at converting ortho-nitrobenzyl-(ONB)-homocysteine than the wildtype enzyme. PC-MjMAT is active over a broad range of temperatures and compatible with MTases from mesophilic organisms. We solved the crystal structures of wildtype and PC-MjMAT in complex with AdoONB and a red-shifted derivative thereof. These structures reveal that aromatic stacking interactions within the ligands are key to accommodating the photocaging groups in PC-MjMAT. The enlargement of the binding pocket eliminates steric clashes to enable AdoMet analogue binding. Importantly, PC-MjMAT exhibits remarkable activity on methionine analogues with red-shifted ONB-derivatives enabling photo-deprotection of modified DNA by visible light.     

Biomimetic S-Adenosylmethionine Regeneration Starting from Multiple Byproducts Enables Biocatalytic Alkylation with Radical SAM Enzymes**

S-Adenosylmethionine (SAM) is an enzyme cofactor involved in methylation, aminopropyl transfer, and radical reactions. This versatility renders SAM-dependent enzymes of great interest in biocatalysis. The usage of SAM analogues adds to this diversity. However, high cost and instability of the cofactor impedes the investigation and usage of these enzymes. While SAM regeneration protocols from the methyltransferase (MT) byproduct S-adenosylhomocysteine are available, aminopropyl transferases and radical SAM enzymes are not covered. Here, we report a set of efficient one-pot systems to supply or regenerate SAM and SAM analogues for all three enzyme classes. The systems’ flexibility is showcased by the transfer of an ethyl group with a cobalamin-dependent radical SAM MT using S-adenosylethionine as a cofactor. This shows the potential of SAM (analogue) supply and regeneration for the application of diverse chemistry, as well as for mechanistic studies using cofactor analogues.