Photoregulation

Anderson, J.M. (1986). Photoregulation of the composition, function, and structure of thylakoid membranes. Annual Review of Plant Physiology, 37, 93-136. 

The third phase of carotenoid accumulation is explored by the observation of a sequential increase of carotenoids following photo-induction. Because synthesis of sterols is not increased after illumination, Bindel et al.12) concluded that the photoregulation takes place between farnesylpyrophosphate and the colored carotenoids, at least for Fusarium. 

Winner, S. Rubin, and A. Riklin, Photoregulation of papain activity through anchoring photochromic azo groups to the enzyme backbone, J. Am. Chem. Soc., 113, 3321-3325(1991). 

It is possible to attach photochromic molecules onto naturally occurring receptors and enzymes and by so doing be able to photoregulate their binding and catalytic activities. These materials have the potential to be used as chemotherapeutic agents and biosensors, and as bioelectronic materials. In most of this work to date spiropyrans have been used as the photochromic element in the system. 

Light is a major regulatory influence on carotenoid synthesis in many plant and microbial systems. A review of this photoregulation has been published. Other papers report the photoinduction of the biosynthesis of phytoene and other carotenoids in strains of Neurospora crassa. " ... 

The photoregulation of the catalytic adivity of 28-Ba2 in the ethanolysis of 29 is illustrated by an experiment (Figure 5.9) in which the catalyst is phototuned HIGH / LOW several times during the reaction by virtue of the complete interconvertibility of stationary states. 

In an interesting application of this result, a photoswitchable unit has been incorporated by covalent linkage into a protein molecule (92JA3150). This has resulted in the ability to photoregulate the binding properties of the protein by effecting minor perturbations in its conformations. 

Thus, a number of processes may take place within supramolecular systems, modulated by the arrangement of the components excitation energy migration, photoinduced charge separation by electron or proton transfer, perturbation of optical transitions and polarizabilities, modification of redox potentials in ground or excited states, photoregulation of binding properties, selective photochemical reactions, etc. 

Castresana, C., Garcia-Luque, I., Alonso, E., Malik, V.S. Cash-more, A.R. (1988). Both positive and negative regulatory elements mediate expression of a photoregulated CAB gene from Nicotiana plumbaginifolia. The EMBO Journal 7, 1929-36. 

Schindler, U. Cashmore, A.R. (1990). Photoregulated gene expression may involve ubiquitous DNA binding proteins. The EM BO Journal 9, 3415-27. 

Azobebzene undergoes trans-cis photoisomerization and this photoswitchable behavior can be used for the photoregulation of various molecular phenomena. A simple example is on-off photoregulation of ester hydrolysis by using an azoben-... 

Figure 3 Photoregulation of polymer-pseudomacrocycle interconversion in a 9(n = 3) + H3N+ — (CH2)6 — NH+ system the circle indicates benzo-18-crown-6.

To realize a photoregulated ion-binding system in calixarenes we introduced two anthracenes near the metal-binding site of calix[4]arene [37-40]. Compound 17 having a podand-type cavity showed poor ion affinity whereas the photochemically produced isomer 18 with a dimeric anthracene-cap showed much improved ion affinity and sharp Na+ selectivity [38,39], Interestingly, 17 immobilized in the PVC membrane plasticized with di(2-ethylhexyl)sebacate underwent ring closure to 18 when it was photoirradiated at 381 nm [40], The... 

Three general methodologies for photoregulating such activities of biomaterials as catalytic, binding, or recognition functions have been suggested (Scheme 2). One method involves the tethering of photoisomerizable units to a protein (Scheme 2(A)). In one photoisomer state, state A, the tertiary structure of the protein is... 

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