HiSOR・生命科学合同セミナー
HiSOR・生命科学合同セミナー
日時 2015年9月4日 （金） 13：30～17：00
場所 放射光科学研究センター 2階 セミナー室
講師 Babak Borhan
(Michigan State University)
1. Progress in Absolute Stereochemical Determination of Organic Molecules via Exciton Coupled Circular Dichroism (13:30～15：00）
During the past 20 years, we have witnessed a great deal of activity directed towards the use of Exciton Coupled Circular Dichroism for the absolute stereochemical determination of organic molecules. The porphyrin tweezer method was among a number of innovative strategies that highlighted the power of ECCD analysis in host/guest complexation of chiral molecules. The use of a variety of zincated porphyrin tweezers as the chromophoric hosts will be discussed, with demonstration of the methodology's feasibility for the absolute stereochemical determination of a number different classes of organic molecules. Application of a new host system, capable of binding molecules with a single site of attachment will be discussed also, with applications for absolute stereochemical determination of amines, cyanohydrins, alcohols, sulfoxides, etc.
2. Lessons from Rhodopsin and Bacteriorhdopsin: Engineered protein/chromophore systems with unique spectroscopic properties (15:30～17:00)
Protein-chromophore interactions are a central component of a wide variety of critical biological processes, such as color vision. Nature has perfected stereoelectronic interactions in each opsin such that a single chromophore (11-cis-retinal) is responsible for the perception of the entire visible spectrum. The sum of the unique interactions between the retinylidene chromophore and the opsins is responsible for wavelength regulation of the colored visual pigments. Our goal is to understand the underlying principles that govern wavelength regulation and to use this knowledge to produce new colorimetric and fluorescent protein tags. To study the fundamental elements that contribute to spectral tuning of a chromophore inside the protein cavity, we have redesigned small, cytosolic retinoid binding proteins as rhodopsin protein mimics, which fully encapsulate all-trans-retinal as a protonated Schiff base. We can regulate the absorption maximum of the pigment from 425 nm to 644 nm using rational mutagenesis designed to alter the electrostatic environment within the binding pocket of the host protein. In addition to retinal, this system can bind a number of diverse chromophores and fluorophores bearing an aldehyde functionality and produce rationally designed protein/chromophore systems that can yield complete control over their spectral properties. In addition to retinal, we are exploring these proteins as hosts for a number of diverse chromophores and fluorophores bearing an aldehyde functionality. The protein/chromophore complexes yield systems that have favorable spectral characteristics for far-red applications, utility as fluorescent protein tags, protein pH sensors, and photochemical switching behavior. These systems are being developed for real world applications as colorimetric and fluorescent protein fusion tags for a host of in vivo applications. Our recent findings in this area will be presented.
問合せ先 根平達夫（総合科学研究科）
松尾光一（放射光科学研究センター）
