http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Fluorescence Enhancement of a Microbial Rhodopsin via Electronic Reprogramming
Marí,n, Marí,a del Carmen,Agathangelou, Damianos,Orozco-Gonzalez, Yoelvis,Valentini, Alessio,Kato, Yoshitaka,Abe-Yoshizumi, Rei,Kandori, Hideki,Choi, Ahreum,Jung, Kwang-Hwan,Haacke, Stefan American Chemical Society 2019 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.141 No.1
<P>The engineering of microbial rhodopsins with enhanced fluorescence is of great importance in the expanding field of optogenetics. Here we report the discovery of two mutants (W76S/Y179F and L83Q) of a sensory rhodopsin from the cyanobacterium <I>Anabaena</I> PCC7120 with opposite fluorescence behavior. In fact, while W76S/Y179F displays, with respect to the wild-type protein, a nearly 10-fold increase in red-light emission, the second is not emissive. Thus, the W76S/Y179F, L83Q pair offers an unprecedented opportunity for the investigation of fluorescence enhancement in microbial rhodopsins, which is pursued by combining transient absorption spectroscopy and multiconfigurational quantum chemistry. The results of such an investigation point to an isomerization-blocking electronic effect as the direct cause of instantaneous (subpicosecond) fluorescence enhancement.</P> [FIG OMISSION]</BR>
Polycrystalline Graphene with Single Crystalline Electronic Structure
Brown, Lola,Lochocki, Edward B.,Avila, Josex301,Kim, Cheol-Joo,Ogawa, Yui,Havener, Robin W.,Kim, Dong-Ki,Monkman, Eric J.,Shai, Daniel E.,Wei, Haofei I.,Levendorf, Mark P.,Asensio, Marí,a,Shen American Chemical Society 2014 NANO LETTERS Vol.14 No.10
<P>We report the scalable growth of aligned graphene and hexagonal boron nitride on commercial copper foils, where each film originates from multiple nucleations yet exhibits a single orientation. Thorough characterization of our graphene reveals uniform crystallographic and electronic structures on length scales ranging from nanometers to tens of centimeters. As we demonstrate with artificial twisted graphene bilayers, these inexpensive and versatile films are ideal building blocks for large-scale layered heterostructures with angle-tunable optoelectronic properties.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2014/nalefd.2014.14.issue-10/nl502445j/production/images/medium/nl-2014-02445j_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl502445j'>ACS Electronic Supporting Info</A></P>
Rhee, Hyun-Woo,Choi, So Jung,Yoo, Sang Ho,Jang, Yong Oh,Park, Hun Hee,Pinto, Rosa Marí,a,Cameselle, Josex301,Carlos,Sandoval, Francisco J.,Roje, Sanja,Han, Kyungja,Chung, Doo Soo,Suh, Junghun American Chemical Society 2009 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.131 No.29
<P>Flavins, comprising flavin mononucleotide (FMN), flavin adenine dinucleotide (FAD), and riboflavin (RF, vitamin B(2)), play important roles in numerous redox reactions such as those taking place in the electron-transfer chains of mitochondria in all eukaryotes and of plastids in plants. A selective chemosensor for flavins would be useful not only in the investigation of metabolic processes but also in the diagnosis of diseases related to flavins; such a sensor is presently unavailable. Herein, we report the first bifunctional chemosensor (PTZ-DPA) for flavins. PTZ-DPA consists of bis(Zn(2+)-dipicolylamine) and phenothiazine. Bis(Zn(2+)-dipicolylamine) (referred to here as XyDPA) was found to be an excellent catalyst in the conversion of FAD into cyclic FMN (riboflavin 4',5'-cyclic phosphate, cFMN) under physiological conditions, even at pH 7.4 and 27 degrees C, with less than 1 mol % of substrate. Utilizing XyDPA's superior function as an artificial FMN cyclase and phenothiazine as an electron donor able to quench the fluorescence of an isoalloxazine ring, PTZ-DPA enabled selective fluorescent discrimination of flavins (FMN, FAD, and RF): FAD shows ON(+), FMN shows OFF(-), and RF shows NO(0) fluorescence changes upon the addition of PTZ-DPA. With this selective sensing property, PTZ-DPA is applicable to real-time fluorescent monitoring of riboflavin kinase (RF to FMN), alkaline phosphatase (FMN to RF), and FAD synthetase (FMN to FAD).</P>
Fluorenyl Based Macrocyclic Polyradicaloids
Lu, Xuefeng,Lee, Sangsu,Hong, Yongseok,Phan, Hoa,Gopalakrishna, Tullimilli Y.,Herng, Tun Seng,Tanaka, Takayuki,Sandoval-Salinas, Marí,a Eugenia,Zeng, Wangdong,Ding, Jun,Casanova, David,Osuka, At American Chemical Society 2017 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.139 No.37
<P>Synthesis of stable open-shell polyradicaloids including control of intramolecular spin-spin interactions is a challenging topic in organic chemistry and materials science. Herein, we report the synthesis and physical characterization of two series of fluorenyl based macrocyclic polyradicaloids. In one series (FR-MCn, n = 4-6), the fluorenyl radicals are directly linked at 3,6-positions; whereas in the other series (MC-FnAn, n = 3-5), an additional ethynylene moiety is inserted between the neighboring fluorenyl units. To access stable macrocyclic polyradicaloids, three synthetic methods were developed. All of these stable macrocycles can be purified by normal silica gel column chromatography under ambient conditions. In all cases, moderate polyradical characters were calculated by restricted active space spin-flip method due to the moderate intramolecular antiferromagnetic spin-spin interactions. The excitation energies from the low-spin ground state to the lowest high-spin excited state were evaluated by superconducting quantum interference device measurements. Their physical properties were also compared with the respective linear fluorenyl radical oligomers (FR-n, n = 3-6). It is found that the geometry, i.e., the distortional angle and spacer (w or w/o ethynylene) between the neighboring fluorenyl units, has significant effect on their polyradical character, excitation energy, one-photon absorption, two-photon absorption and electrochemical properties. In addition, the macrocyclic tetramers FR-MC4 and MC-F4A4 showed global antiaromatic character due to cyclic pi-conjugation with 36 and 44 pi-electrons, respectively.</P>
Molecular link between auxin and ROS-mediated polar growth
Mangano, Silvina,Denita-Juarez, Silvina Paola,Choi, Hee-Seung,Marzol, Eliana,Hwang, Youra,Ranocha, Philippe,Velasquez, Silvia Melina,Borassi, Cecilia,Barberini, Marí,a Laura,Aptekmann, Ariel Ale National Academy of Sciences 2017 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.114 No.20
<P>Root hair polar growth is endogenously controlled by auxin and sustained by oscillating levels of reactive oxygen species (ROS). These cells extend several hundred-fold their original size toward signals important for plant survival. Although their final cell size is of fundamental importance, the molecular mechanisms that control it remain largely unknown. Here we show that ROS production is controlled by the transcription factor RSL4, which in turn is transcriptionally regulated by auxin through several auxin response factors (ARFs). In this manner, auxin controls ROS-mediated polar growth by activating RSL4, which then up-regulates the expression of genes encoding NADPH oxidases (also known as RESPIRATORY BURST OXIDASE HOMOLOG proteins) and class III peroxidases, which catalyze ROS production. Chemical or genetic interference with ROS balance or peroxidase activity affects root hair final cell size. Overall, our findings establish a molecular link between auxin and ROS-mediated polar root hair growth.</P>