Reversible conformational changes induced by light in poly(L-glutamic acid) with photochromic side chains

Pieroni, Osvaldo; Houben, Julien L.; Fissi, Adriano; Costantino, Paolo; Ciardelli, Francesco

doi:10.1021/ja00538a039

Cited by 95 publications

(41 citation statements)

References 2 publications

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“…The strong geometrical difference between the extended trans form and the compact cis form in the gas phase and in solution may provide important details on the distribution and the dynamics of the azobenzene guest into hosts such as cyclodextrins 6 and crown ethers 7 or on the conformational changes of polypeptide chains. 8 The mechanism by which the Z-E isomerization takes place is not unequivocally established since two opposing pathways have been proposed: the reaction may proceed either by rotation about the N=N double bond or by flip-flop inversion of one of the nitrogen atoms. 9 The rotation and inversion pathways are competitive, but one may be favored over the other, depending of the electronic nature of the substituents covalently bonded to one or both the phenyl rings and of the polarity of the reaction medium.…”

Section: Introductionmentioning

confidence: 99%

Kinetics of the Z-E isomerization of monosubstituted azobenzenes in polar organic and aqueous micellar solvents

Maria¹,

Fontana²,

Gasbarri³

et al. 2008

Arkivoc

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The rates of Z-E isomerization of azobenzene and seven 4-substituted derivatives (CH3, CF3, OCH3, n-Butyl, Ot-Butyl, Br, F) have been investigated at 25 °C in ethanol, in methanol, in methanol/water mixtures and in aqueous solutions of ionic and non-ionic micelles by recording in the dark the spectral changes observed after exposure to UV light of the samples. The competitive contributions of the rotation vs. inversion mechanisms by which the isomerization of azobenzenes can occur have emerged from V-shaped Hammett plots. The obtained rate constants can be used as polarity indicators of the different micro-heterogeneous media with two main advantages with respect to other probes. Firstly they are not affected by hydrogen bonding between the substrate and the environment, as in the case of push-pull azobenzenes. Secondly, the derived substrate-independent Hammett  values allow to separate the effects of orientation of the probe from the polarity of the supramolecular aggregate.

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Section: Introductionmentioning

confidence: 99%

Kinetics of the Z-E isomerization of monosubstituted azobenzenes in polar organic and aqueous micellar solvents

Maria¹,

Fontana²,

Gasbarri³

et al. 2008

Arkivoc

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“…In general, there are two fundamental classes of photoswitchable biomolecules that have been developed (5): single-cycle and multicycle photoswitches. Single-cycle photoswitches are activated by the removal of protective groups on photoirradiation (6)(7)(8)(9). Multicycle photoswitches have also been reported for controlling enzyme activities and ligand binding activities through direct photoisomerization of chromophores, indirect control of chromophore binding and unbinding, and by control of substrate access to immobilized enzymes in responsive hydrogels (10)(11)(12)(13)(14)(15)(16).…”

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confidence: 99%

Photoresponsive polymer–enzyme switches

Shimoboji

Larenas²,

Fowler³

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

314

240

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The ability to photoregulate enzyme activities could provide important new opportunities for development of diagnostic assays, sequential bioprocessing, and lab assays in both traditional and microfluidic formats. We show here that the photoinduced changes in the size and hydration of a ''smart'' polymer chain coil can be used to regulate substrate access and enzyme activity when conjugated to the enzyme at a specific point just outside the active site. The photoresponsive polymers thus serve jointly as antennae and actuators that reversibly respond to distinct optical signals to switch the polymer-enzyme conjugates on and off, and work when the conjugate is free in solution or when immobilized on magnetic beads. smart polymer ͉ photoswitch ͉ biotechnology ͉ bioMEMs ͉ bioconjugates

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“…Photoregulation of polypeptide structure has been an active area of research (Ciardelli and Pieroni, 2001), with the azobenzenes making significant contributions. Azo-modified poly (L-alanine) (Sisido et al, 1991a,b), poly(L-glutamic acid) (Houben et al, 1983;Pieroni et al, 1980), and poly(L-lysine) (Malcolm and Pieroni, 1990), among others, have been prepared. Depending on the system, photoisomerization may cause no change (Houben et al, 1983) or can induce a substantial conformational change, including transitions from ordered chiral helix to disordered achiral chain Yamamoto and Nishida, 1991;Montagnoli et al, 1983), changes in the a-helix content, or even reversible a-helix to b-sheet conversions (Fissi et al, 1987).…”

Section: Photobiological Experimentsmentioning

confidence: 99%