Reversal in the kinetics of the M state decay of D96N bacteriorhodopsin: probing of enzyme catalyzed reactions

Bacteriorhodopsin as a Photochromic Retinal Protein for Optical Memories

“…Some of these proposals shall be mentioned here briefly. The largest group in this section describes the effects of anesthetics on the BR photocycle and its potential uses, − Also biosensors for monitoring, for example, pesticides , and enzymic reactions where BR acts as an indicator are described. Even for the detection of high-energy radiation BR seems to be applicable.…”

Bio-doped Nanocomposite Polymers: Sol−Gel Bioencapsulates

“…Spectroscopic investigations of myoglobin, hemoglobin, cytochrome c , cytochrome c peroxidase, catalase, monellin, oncomodulin, glutamate dehydrogenase, glucose oxidase, and nitrobenzoxadiazole- and acryloidan-labeled bovine and human albumins entrapped in silica and siloxane hydrogels and xerogels indicate that the proteins are sequestered within 3−10-nm hydrated pockets wherein they substantially retain nanosecond and sub-nano-second dynamics and at least aspects of global mobility, akin to the dissolved biomolecules. − Indeed, fluorescence studies of silica-entrapped glucose oxidase indicate that the rotational mobility of the enzyme is approximately 50% of that in solution, that the folding kinetics of the flavin moiety are greatly reduced, but that the local motions of the active site pocket are similar to those in solution. , Similarly, the silica-entrapped photoactive proton-pump bacteriorhodopsin shows a decrease in the rate of decay of its excited M state, but retains enough global mobility to change its conformational state and therefore function. − …”

“…Although optical and amperometric configurations are readily constructed for chromoproteins and oxidoreductases, other proteins can also be applied, providing that the substrate/product can be monitored optically/electrochemically. Thus, the sol−gel-entrapped hydrolases cholinesterase, acetylcholinesterase, butyrylcholinesterase, phosphodiesterase, urease, and penicillinase have been used as direct and inhibition-based biosensors for the optical and potentiometric monitoring of acetylcholine, organophosphate pesticides, penicillin, and urea (Table ). − Particularly interesting is the construction of coupled optical sensors employing bacteriorhodopsin together with urease, acetylcholine esterase, or penicillinasethe action of the hydrolase alters the pH and thus the protonation state of and hence the rate of decay of the photoactive M-state of bacteriorhodopsin 4 Examples of Sol−Gel Optical, Electrochemical, and Immunochemical Biosensors Using Hydrolase, Ligand-Binding, and Photoactive Proteins a a Abbreviations: 3-HEAGS, 3-(1‘-hydroxy-2‘-(2‘ ‘-hydroxyethylamino)ethoxy)propyl-glyceroxysiloxane; PGS, poly(glyceryl silicate); TMOS, tetramethoxysilane.…”

Films based on bacteriorhodopsin in sol-gel matrices

“…The chemical environment of bR also influences the photocycle parameters 5 . For example, humidity 6,7 , solutions of local anaesthetics 8 , organic vapours 9 , ammonium ions and amines 10,11 , and ammonia 12 all have demonstrable effects on the spectral and kinetic parameters. The effect of pH has also been studied 13 .…”

“…Hydrolysis and condensation of tetra-alkoxysilanes during the sol-gel process help to form a solid silicate around the sensing molecule, which is dissolved in the liquid phase 16 . bR retains its optical properties when entrapped in silicate glass by the sol-gel process 18,19 , and could therefore be used for the envisaged biosensor application 10 . The preparation of dry films based on bR of high optical quality will considerably enhance the area of bR applications as sensitive elements of integrated optic and fibre-optic sensors.…”