Three photochromic reagents were synthesized and examined for their ability to inactivate acetylcholinesterase. They are: N-p-phenylazophenyl-N-phenylcarbamyl chloride (PAPCl), N-p-phenylazophenyl-N-phenylcarbamyl fluoride (PAPF), and N-p-phenylazophenyl-V-methylcarbamyl chloride (PAMCC1). These photochromic compounds can exist as cis and trans isomers that are interconvertible under the influence of light of selected wavelengths. In the trans configuration, the azobenzene portion of the molecule is planar; this is not so for the cis isomers. As a result, the two isomeric forms of each of the reagents acylated the enzyme acetylcholinesterase at different rates; deacylation rates also differed. In all cases, the cis isomers acylated the enzyme at faster rates than the trans isomers. The reverse was true for the deacylation reaction. The most active reagent was PAMCC1. Kinetic constants were evaluated and some observations were made on the utility of photochromic reagents as probes of the topography of biological systems having the property of specificity
Title: Photoregulation of biological activity by photocromic reagents. II. Inhibitors of acetylcholinesterase Bieth J, Vratsanos SM, Wassermann N, Erlanger BF Ref: Proc Natl Acad Sci U S A, 64:1103, 1969 : PubMed
The enzymic activity of acetylcholinesterase can be photoregulated through the mediation of photochromic inhibitors of the enzyme. N-p-phenylazophenyl-N-phenylcarbamyl fluoride, an irreversible inhibitor of acetylcholinesterase, exists as two geometric isomers which are interconvertible through the action of light. The cis isomer, which predominates after exposure to light of 320 nm, is more active than the trans isomer, which results from exposure to light of 420 nm. It was possible, therefore, to use light energy to regulate the inactivation of the enzyme. Similarly, levels of acetylcholinesterase activity could be photo-regulated in a completely reversible manner by means of the photochromic reversible inhibitor p-phenylazophenyltrimethylammonium chloride. These experiments can serve as models for similar phenomena observed in nature, particularly in photoperiodic rhythms of higher animals.
Title: Photoregulation of an enzymic process by means of a light-sensitive ligand Kaufman H, Vratsanos SM, Erlanger BF Ref: Science, 162:1487, 1968 : PubMed
A specific inactivator of chymotrypsin, p-azophenyldiphenylcarbamyl chloride, exists as two geometric isomers, cis and trans, which are interconvertible by means of light. The cis-isomer is five times more reactive than the more stable trans-isomer, and is obtained by exposure of the latter to light of 320 nanometer wavelength. The trans-isomer can be regained by exposure of the cis-isomer to light of 420 nanometer wavelength. This interconversion can be made to occur in aqueous solution in the presence of the enzyme under conditions in which the trans-isomer reacts relatively slowly with chymotrypsin. Thus, it is possible to regulate the rate of inactivation of chymotrypsin by using light of the appropriate wavelength. This system is presented as a model for some of the light-sensitive metabolic systems present in living organisms.
2 lessTitle: Physiological and pharmacological manipulations with light flashes Lester HA, Nerbonne JM Ref: Annu Rev Biophys Bioeng, 11:151, 1982 : PubMed
Three photochromic reagents were synthesized and examined for their ability to inactivate acetylcholinesterase. They are: N-p-phenylazophenyl-N-phenylcarbamyl chloride (PAPCl), N-p-phenylazophenyl-N-phenylcarbamyl fluoride (PAPF), and N-p-phenylazophenyl-V-methylcarbamyl chloride (PAMCC1). These photochromic compounds can exist as cis and trans isomers that are interconvertible under the influence of light of selected wavelengths. In the trans configuration, the azobenzene portion of the molecule is planar; this is not so for the cis isomers. As a result, the two isomeric forms of each of the reagents acylated the enzyme acetylcholinesterase at different rates; deacylation rates also differed. In all cases, the cis isomers acylated the enzyme at faster rates than the trans isomers. The reverse was true for the deacylation reaction. The most active reagent was PAMCC1. Kinetic constants were evaluated and some observations were made on the utility of photochromic reagents as probes of the topography of biological systems having the property of specificity
Title: Photoregulation of biological activity by photocromic reagents. II. Inhibitors of acetylcholinesterase Bieth J, Vratsanos SM, Wassermann N, Erlanger BF Ref: Proc Natl Acad Sci U S A, 64:1103, 1969 : PubMed
The enzymic activity of acetylcholinesterase can be photoregulated through the mediation of photochromic inhibitors of the enzyme. N-p-phenylazophenyl-N-phenylcarbamyl fluoride, an irreversible inhibitor of acetylcholinesterase, exists as two geometric isomers which are interconvertible through the action of light. The cis isomer, which predominates after exposure to light of 320 nm, is more active than the trans isomer, which results from exposure to light of 420 nm. It was possible, therefore, to use light energy to regulate the inactivation of the enzyme. Similarly, levels of acetylcholinesterase activity could be photo-regulated in a completely reversible manner by means of the photochromic reversible inhibitor p-phenylazophenyltrimethylammonium chloride. These experiments can serve as models for similar phenomena observed in nature, particularly in photoperiodic rhythms of higher animals.
Title: Photoregulation of an enzymic process by means of a light-sensitive ligand Kaufman H, Vratsanos SM, Erlanger BF Ref: Science, 162:1487, 1968 : PubMed
A specific inactivator of chymotrypsin, p-azophenyldiphenylcarbamyl chloride, exists as two geometric isomers, cis and trans, which are interconvertible by means of light. The cis-isomer is five times more reactive than the more stable trans-isomer, and is obtained by exposure of the latter to light of 320 nanometer wavelength. The trans-isomer can be regained by exposure of the cis-isomer to light of 420 nanometer wavelength. This interconversion can be made to occur in aqueous solution in the presence of the enzyme under conditions in which the trans-isomer reacts relatively slowly with chymotrypsin. Thus, it is possible to regulate the rate of inactivation of chymotrypsin by using light of the appropriate wavelength. This system is presented as a model for some of the light-sensitive metabolic systems present in living organisms.
