Inhibition or initiation of a radical polymerization reaction by an ultraviolet-induced enzymatic process.
ABSTRACT alpha-Chymotrypsin was modified to a light-controllable enzyme derivative by acylating active serine 195 residue with a cinnamoyl group or analogue. Upon UV irradiation the acylgroup could be isomerized, leading to release of the inhibiting group. Enzymatic activity could thus be regulated by means of UV light. A full 100% inhibition of the enzymatic activity could not be reached by the cinnamoyl derivative. Only posttreatment with diisopropylfluorophosphate yields a fully inactive enzyme derivative. The shelf-life of the inhibited enzyme was rather poor. Only freeze-dried samples could be used for several months without significant recovery of activity. Adapting the sensitivity of the system to visible light seems limited to the size of an enzyme's active site. Combination of the enzymatic system producing an inhibitor or an initiator with a polymerization reaction can result in a photographic process with a higher amplification factor.
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ABSTRACT: Levels of acetylcholinesterase activity can be made to vary in response to the presence or absence of sunlight in a system that can be considered as a model for photoperiodic processes found in nature. The enzyme is rendered photosensitive by the presence of a photochromic inhibitor, N-p-phenylazophenylcarbamyl choline, which changes from a trans to a cis isomer under the influence of the light of the sun and reverts back to the trans isomer in the dark. The two isomers differ in their ability acetylcholinesterase, thus rendering the enzyme system responsive to sunlight. The relationship of this system to photoresponsive processes in nature is discussed, and a possible role in photoregulation is suggested for naturally occurring carotenoids.Proceedings of the National Academy of Sciences 08/1970; 66(3):850-4. · 9.74 Impact Factor
- Journal of Biological Chemistry 06/1949; 179(1):189-99. · 4.65 Impact Factor
- FEBS letters 07/1971; 15(2):118-120. · 3.54 Impact Factor