つくばリポジトリ SR 8 1 137

0
1
7
11 months ago
Preview
Full text
Response speed cont r ol of hel i ci t y i nver si on based on a “r egul at or y enzyme” l i ke st r at egy 著者 j our nal or publ i cat i on t i t l e vol ume page r ange year 権利 URL Sai r enj i Shi ho, Aki ne Shi gehi sa, Nabeshi ma Tat suya Sci ent i f i c r epor t s 8 137 2018- 01 (C) The Aut hor (s) 2017 Thi s ar t i cl e i s l i censed under a Cr eat i ve Commons At t r i but i on 4. 0 I nt er nat i onal Li cense, whi ch per mi t s use, shar i ng, adapt at i on, di st r i but i on and r epr oduct i on i n any medi um or f or mat ,as l ong as you gi ve appr opr i at e cr edi t t o t he or i gi nal aut hor (s) and t he sour ce, pr ovi de a l i nk t o t he Cr eat i ve Commons l i cense, and i ndi cat e i f changes wer e made. The i mages or ot her t hi r d par t y mat er i al i n t hi s ar t i cl e ar e i ncl uded i n t he ar t i cl e’ s Cr eat i ve Commons l i cense, unl ess i ndi cat ed ot her wi se i n a cr edi t l i ne t o t he mat er i al .I f mat er i al i s not i ncl uded i n t he ar t i cl e’ s Cr eat i ve Commons l i cense and your i nt ended use i s not per -mi t t ed by st at ut or y r egul at i on or exceeds t he per mi t t ed use, you wi l l need t o obt ai n per mi ssi on di r ect l y f r om t he copyr i ght hol der .To vi ew a copy of t hi s .ht t p: hdl .handl e. net /2241/ 00150983 doi: 10.1038/s41598-017-16503-1 Cr eat i ve Commons :表示 ht t p: cr eat i vecommons. or g/ l i censes/ by/ 3. 0/ deed. j a www.nature.com/scientificreports OPEN Received: 5 October 2017 Response speed control of helicity inversion based on a “regulatory enzyme”-like strategy Shiho Sairenji1, Shigehisa Akine 2 Tatsuya Nabeshima 1 Accepted: 14 November 2017 Published: xx xx xxxx In biological systems, there are many signal transduction cascades in which a chemical signal is transferred as a series of chemical events. Such successive reaction systems are advantageous because the eiciency of the functions can be inely controlled by regulatory enzymes at an earlier stage. However, most of artiicial responsive molecules developed so far rely on single-step conversion, whose response speeds have been diicult to be controlled by external stimuli. In this context, developing artiicial conversion systems that have a regulation step similar to the regulatory enzymes has been anticipated. Here we report a novel artiicial two-step structural conversion system in which the response speed can be controlled based on a regulatory enzyme-like strategy. In this system, addition of luoride ion caused desilylation of the siloxycarboxylate ion attached to a helical complex, resulting in the subsequent helicity inversion. The response speeds of the helicity inversion depended on the reactivity of the siloxycarboxylate ions; when a less-reactive siloxycarboxylate ion was used, the helicity inversion rate was governed by the desilylation rate. This is the irst artiicial responsive molecule in which the overall response speed can be controlled at the regulation step separated from the function step. In responsive molecules using a chemical stimulus, binding with a chemical species causes a structural change that leads to responsive functions (Fig. 1a).Representative examples in biological systems are allosteric enzymes1,2, which undergo a structural change upon binding with an efector, resulting in a responsive function. here are also many artiicial responsive molecules using chemical species as the trigger3–8, and some of them are used to drive molecular machines9–11. In these systems, the response speeds are determined by the intrinsic reaction rates of the structural conversion, which are usually diicult to change without changing the reaction conditions. In biological systems, there are cascade systems in which a chemical signal is transferred as a series of chemical events prior to the structural changes leading to their functions (Fig. 1b)12–21. A signiicant feature of such successive reactions is that they have a regulatory enzyme (or a rate-limiting enzyme) that controls the eiciency of the functions not at the inal function step, but at an earlier stage. his preceding step is important for ine-tuning of the overall activity. In artiicial functional systems, however, there are rare examples of such signal transduction cascades whose functions are controlled at a prior stage in a series of two or more successive chemical events. Nevertheless, such a cascade system is advantageous, because a regulation step, which could control the overall response speed and/or time proiles of the functions, can be separated from the inal function step (Fig. 1b).his would enable not only to switch on and of the functions, but also to set the activity at any level. In addition, the unique time-programmable features would be introduced in discrete functional molecular systems; such a time-programmable material, which has recently attracted increasing attention, has been achieved only in supramolecular aggregate systems22. In this context, developing artiicial conversion systems that have a regulation step similar to the regulatory enzymes found in biomolecules has been anticipated. hus, we designed a novel simpliied artiicial system for a signal transduction cascade that enables a two-step conversion using luoride ion as the signal input. he luoride ion causes desilylation of a chiral siloxycarboxylate ion during the irst step and this conversion controls the response speeds of the helicity inversion of dynamic helical complex LZn3La23–25 during the inal step (Fig. 1c).Helicity inversion is one of the basic and important structural conversions26–34, because helical structures35–39 are ubiquitous structural motifs in various types of Faculty of Pure and Applied Sciences, University of Tsukuba, Tennodai, Tsukuba, Ibaraki, Japan. Graduate School of Natural Science and Technology /Nano Life Science Institute (WPI-NanoLSI),Kanazawa University, Kakuma-machi, Kanazawa, Japan. Correspondence and requests for materials should be addressed to S.A. email: akine@se.kanazawa-u.ac.jp) or T.N. email: nabesima@chem.tsukuba.ac.jp) SCIENTIFIC REPORTS |2018) 8:137 |DOI: s 1 www.nature.com/scientificreports/ a One-step structural conversion for responsive functions structural conversion binding or reaction c flow of stimulus transducer unit O F Si structural conversion controllable reaction rate intrinsic reaction rate regulation step function step HO R O O flow of chemical signal HO R O O structure conversion (helicity inversion) function step Control of response speed functions structural conversion R O structure conversion (desilylation) regulation step b Signal transduction cascade for responsive functions binding or reaction Si O F– stimulus chemical signal response speed =intrinsic reaction rate stimulus transducer unit functions 3+ NO O Zn N O O O N O O O N Zn O La Me Me O O O N Zn N O O (M)-form LZn3La left-handed 3+ N OMeO ZnO N La O O Zn N O N O Me O (P)-form LZn3La right-handed O N O O N ZnO Easy to control the overall response speed Figure 1. Concept and design of responsive functional systems based on a regulatory enzyme-like strategy. a) One-step structural conversion for responsive function. b) Multi-step structural conversion for responsive functions. he function activity (reaction rates) may be controlled at an earlier step called the regulation step. c) Design of a new artiicial system for helicity inversion mediated by desilylation of the coordinating siloxycarboxylate ions at the regulation step. R =Ph (H2–)HO +20 R =Me (H1–)O R Si O O Si O CD/mdeg 0 HO –20 O S1·H HO O S2·H 40 Si O R HO O O HO R =Me (S1–)60 R =Ph (S2–)HO O H1·H 80 250 300 350 wavelength/nm 400 HO O H2·H 450 Figure 2. CD spectra of LZn3La (0.20 mM, acetonitrile/chloroform, 9:1, path length 1 mm, 295 K) in the presence of 3 equiv of chiral carboxylic acids (S1·H, S2·H, H1·H, and H2·H) and 3 equiv of DABCO. substances. In the present LZn3La system, the helicity is sensitively afected by structural diferences in the chiral carboxylate ions40,41, whereas the helicity inversion rate is not signiicantly afected (thus called the intrinsic helix inversion rate, hereater).hese facts inspired us to design a system in which helicity inversion is driven by a slow chemical transformation in the coordinating carboxylate ions. In fact, there have been several helical metal complexes that can change their helix inversion rates23,42,43 by replacing the central metal ion. he time-programming in these systems needs to change the intrinsic helix inversion rates, whereas the helix inversion rates of the present system can be controlled at the regulation step without changing the intrinsic helix inversion rates. We now report this new type of two-step structural conversion in which the response speed of the helicity inversion at the inal function step was efectively controlled at the regulation step using siloxycarboxylate ions with diferent reactivities. Results and Discussion Requirements for the F−-triggered helicity inversion in this system is that the carboxylate ions before and ater the desilylation should induce opposite helicities of the LZn3La. hus, we investigated the CD spectra of LZn3La in the presence of several chiral carboxylic acids (S1·H, S2·H, H1·H, and H2·H) Fig. 2).DABCO (1,4-diazabicyclo[2.2.2]octane) was used to deprotonate these carboxylic acids. We have already demonstrated that chiral carboxylate ions such as H1− and H2− eiciently shit the P/M equilibrium of the LZn3La helix and that two molecules of these carboxylate ions can interact with LZn3La from the CD spectroscopic titration experiments40,41. When the siloxycarboxylate ion, S1− or S2−,was present, a negative Cotton efect was observed at 350 nm, which is indicative of the (M)-helicity of LZn3La based on a comparison with related complexes44–47. In contrast, a positive Cotton efect was observed at 350 nm when the hydroxycarboxylate ion, H1− or H2−,was present under the same conditions. he observed diferences in the signs of the Cotton efect should be attributed to the opposite preference of the (M)-and (P)-forms. Consequently, the-hydroxycarboxylate ions and the corresponding siloxy derivatives induced opposite helicities although they have the same stereoconiguration. SCIENTIFIC REPORTS |2018) 8:137 |DOI: s 2 www.nature.com/scientificreports/ a (i) ii) 40 +20 0 CD/mdeg CD/mdeg 0 After 650 min CD at 352 nm/mdeg After 560 min 20 b 20 After 2 min 40 –60 Before addition 80 250 300 350 wavelength/nm 400 20 –40 After 2 min 60 80 450 250 Before addition 300 350 wavelength/nm 400 450 i) R =Me (S1–)20 0 –20 ii) R =Ph (S2–)40 –60 –80 0 200 400 time/min 600 Figure 3. CD spectral observation of helicity inversion triggered by F– addition. a) CD spectral changes of LZn3La (0.20 mM, acetonitrile/chloroform, 9:1, path length 1 mm, 295 K) in the presence of siloxycarboxylic acid (3 equiv) and DABCO (3 equiv) ater the addition of tetrabutylammonium luoride (i, 3 equiv for S1·H; ii, 4 equiv for S2·H).b) Time course of the CD intensity changes (352 nm).herefore, we expected that, if the silyl group in S1− and S2− is removed by the reaction with luoride ion, a responsive helicity inversion should take place. Indeed, the addition of luoride ion caused signiicant changes in the CD spectra. While the siloxycarboxylate ion S1− induced a negative Cotton efect at 350 nm attributable to the (M)-helicity of LZn3La (Fig. 3a,i),the Cotton efect started to immediately decrease ater the addition of 3 equiv of luoride ion. he intensity decreased with approximate irst-order kinetics and turned positive ater 30 min. he spectral changes were almost completed ater 100 min (Fig. 3b,i) to result in a CD spectrum similar to that of the (P)-helical LZn3La in the presence of H1·H and DABCO (Fig. 2).his suggested that the siloxycarboxylate ion S1− coordinating to LZn3La was converted into the desilylated derivative H1−.his was clearly evidenced by the ESI-MS peak (m/z =611.0 for [LZn3La +H1]2+)observed in the solution ater reaction with the luoride ion (Supplementary Fig. S3).Interestingly, the structures of the siloxycarboxylate ions signiicantly afected the response speeds of the helicity inversion. We similarly prepared the (M)-helical LZn3La complex by using the mandelate-based siloxycarboxylate ion S2− in place of the lactate-based S1−.his helical complex, LZn3La with S2−,also showed a gradual decrease in the CD intensity ater the addition of 3 equiv of luoride ion, but the reaction was so slow that the CD signal did not turn positive even ater 720 min (Supplementary Fig. S5).When the amount of luoride ion was increased from 3 equiv to 4 equiv (Fig. 3a,ii),the helicity was inverted as observed for LZn3La with S1−.However, the reaction was still signiicantly slow compared to the LZn3La–S1− system; the CD signal turned positive ater 120 min, but it took 650 min to complete the reaction (Fig. 3b,ii).he resultant CD spectrum (23.9 mdeg at 350 nm, Fig. 3a,ii) was very similar to that of LZn3La in the presence of H2·H and DABCO (23.7 mdeg at 350 nm, Fig. 2).his indicated that the siloxycarboxylate ion S2− coordinating to LZn3La underwent desilylation to give the hydroxycarboxylate H2−.his was conirmed by the ESI-MS peak ater the reaction (m/z 641.9 for [LZn3La +H2]2+,Supplementary Fig. S6).As already described, it is clear that the helicity inversion of LZn3La was triggered by the luoride ion via the desilylation of S1− or S2− coordinating to the LZn3La helical complex. However, the LZn3La–S1− system showed signiicantly faster response than the LZn3La–S2− system. his diference should mainly arise from the diferent reactivity of the silyl groups in the carboxylate ions S1− and S2− toward the luoride ion. In the case of the lactate-based S1−,the silyl group was completely removed within 3 min (Supplementary Fig. S4),which was evidenced by the 1H NMR analysis. Since the observed half-life of the CD intensity changes (t1/2 ≈20 min) was much longer than that of the desilylation (t1/2

RECENT ACTIVITIES

Tags

つくばリポジトリ Sr つくばリポジトリ Jdi つくばリポジトリ Tjsai 32 1 D G つくばリポジトリ Prc つくばリポジトリ Ck つくばリポジトリ Tjlp つくばリポジトリ Uttac つくばリポジトリ Tcs つくばリポジトリ 24241053Seika
Show more

Document relate

計算機にまつわる宗教戦争 TA小話
0
7
9
「指定訪問看護の事業の人員及び運営に関する基準について」の一部改正について(平成24年3月26日保発0326第6号)
1
4
3
1年男子シングルス結果pdf 最近の更新履歴 熊本県中学テニス連盟
0
45
2
授業提案例 デジ読評価プロジェクト@東京学芸大学 1②新聞を使おう1指導案
0
1
1
緒言(1ページ) 分子研リポート2013 | 分子科学研究所
0
0
1
帰国後登録について 1
0
1
2
別紙様式13「登録試験機関 登録事項変更届」(規則第8条の21関係) 消費者安全法の改正(平成26年6月)|消費者庁
0
0
1
iPS細胞関連技術及びヒトES細胞関連技術に関する特許出願・論文発表の状況について
0
1
6
別表1 法別番号及び制度の略称表、別表2 都道府県番号表
0
27
4
1 2016阻止ネット政策提言docx
0
0
20
BRMoma tate v1 1 最近の更新履歴 Randonneurs MIYAGI BRMoma tate v1 1
0
0
16
○ 介護サービス事業者の指導監査等について | 函館市
0
1
19
平成21年度集計結果 「節電して☆クオカード☆をもらおう!」節電チャレンジモニター募集について | 函館市
0
0
3
施設を利用した啓発等について(案) 函館市廃棄物処理施設整備基本計画検討委員会 | 函館市
0
0
1
PDF 建物清掃業務における総合評価落札方式について | 函館市
0
0
10
Show more