Bioluminescence photoproteins, aequorin

The earliest simultaneous measurements of [Ca +Jj and force in smooth muscle were made in strips loaded by microinjection or reversible permeabiliza-tion with the bioluminescent photoprotein aequorin (Neering and Morgan, 1980 Morgan and Morgan,... 

Johnson, F. H., and Shimomura, O. (1978). Introduction to the bioluminescence of medusae, with special reference to the photoprotein aequorin. Method. Enzymol. 57 271-291. 

Kurose, K., Inouye, S., Sakaki, Y., and Tsuji, F. I. (1989). Bioluminescence of the calcium-binding photoprotein aequorin after cysteine modification. Proc. Natl. Acad. Sci. USA 86 80-84. 

It was a common belief that all phenomena of bioluminescence were caused by the luciferin-luciferase reaction until the biolumines-cent protein aequorin was discovered in 1962 (Shimomura et al., 1962). When the terms luciferin and luciferase were found to be unsuitable for categorizing the two bioluminescent proteins, aequorin and another from the tubeworm Chaetopterus, a new term photoprotein was introduced to supplement the term luciferin (Shimomura and Johnson, 1966). Further explanations for the terms luciferin and photoprotein are given below. 

Obelin is a Ca2+-activated bioluminescent photoprotein that has been isolated from the marine polyp Obelia longissima. Binding of calcium ions determines a luminescent emission. The protein consists of 195 amino acid residues [264] and is composed of apoobelin, coelenterazine, and oxygen. As aequorin, it contains three EF-hand Ca2+-binding sites and the luminescent reaction may be the result of coelenterazine oxidation by way of an intramolecular reaction that produces coelenteramide, C02, and blue light. As for aequorin, the luminescent reaction of obelin is sensitive to calcium and the protein was used in the past as an intracellular Ca2+ indicator. More recently, the cloning of cDNA for apoobelin led to the use of recombinant obelin as a label in different analytical systems. 

Mori K, Maki S, Niwa H, Ikeda H, Hirano T. Real light emitter in the bioluminescence of the calcium-activated photoproteins aequorin and obelin light emission from the singlet-excited state of coelenteramide phenolate anion in a contact ion pair. Tetrahedron 2006 62 6272-88. 

Coelenterazine. C26H21N3O3, Mr 423.47. Prosthetic group with the imidazopyrazine structure of the photoprotein aequorin from bioluminescent jelly fish species of the genus Aequorea. A blue luminescence is observed in the presence of traces of Ca ions. Natural aequorin does not need oxygen for bioluminescence, thus it is assumed to exist in the form of a per-... 

S Lizano, S Ramanathan, A Feltus, A Witkowski, S Daunert. Bioluminescence competitive assays for biotin based on photoprotein aequorin. Methods Enzymol 279 296-303, 1997. 

The bioluminescent system of Aequorea is called a photoprotein (aequorin) [64]. The luciferin is bound to the luciferase as a peroxide so that molecular oxygen is not required. The addition of calcium ions triggers the luminescence by means of a conformational change of the protein. 

ImmunO lSS iy. Chemiluminescence compounds (eg, acridinium esters and sulfonamides, isoluminol), luciferases (eg, firefly, marine bacterial, Benilla and Varela luciferase), photoproteins (eg, aequorin, Benilld), and components of bioluminescence reactions have been tested as replacements for radioactive labels in both competitive and sandwich-type immunoassays. Acridinium ester labels are used extensively in routine clinical immunoassay analysis designed to detect a wide range of hormones, cancer markers, specific antibodies, specific proteins, and therapeutic dmgs. An acridinium ester label produces a flash of light when it reacts with an alkaline solution of hydrogen peroxide. The detection limit for the label is 0.5 amol. 

Effect of pH. The light emission from most bioluminescence systems is affected by the pH of the medium, and some luciferases and photoproteins can be made inactive at certain pH ranges without resulting in permanent inactivation. For example, the luminescence of euphausiids can be quenched at pH 6, the luminescence of aequorin can be suppressed at pH 4.2-4A, and the luciferase of the decapod shrimp Oplophorus becomes inactive at about pH 4. In the case of Cypridina luminescence, however, the acidification of an extract to below pH 5 results in an irreversible inactivation of the luciferase. 

If a bioluminescence system is not inhibited by anaerobic conditions, the luminescence system probably does not require oxygen. In such a case, the luminescence system might require hydrogen peroxide, or it might involve an aequorin-like photoprotein that does not require oxygen for luminescence. 

Quantula (Dyakia), 180, 334 Quantum yield, xvi, 361, 362 aequorin, 104, 106, 110 aldehydes in bacterial bioluminescence, 36, 41 Chaetopterus photoprotein, 224 coelenterazine, 85, 143, 149 Cypridina luciferin, 69-71 definition, xvi, 361 Diplocardia bioluminescence, 242 firefly luciferin, 12 fluorescent compound F, 73 Latia luciferin, 190 pholasin, 197 PMs, 286... 

Today, bioluminescence reactions are used as indispensable analytical tools in various fields of science and technology. For example, the firefly bioluminescence system is universally used as a method of measuring ATP (adenosine triphosphate), a vital substance in living cells Ca2+-sensitive photoproteins, such as aequorin from a jellyfish, are widely utilized in monitoring the intracellular Ca2+ that regulates various important biological processes and certain analogues... 

Bioluminescence is a special form of chemiluminescence found in biological systems. In bioluminescence, an enzyme or a photoprotein increases the efficiency of the luminescence reaction. Luciferase and aequorin are two examples of these biological catalysts. The quantum yield (e.g., total photons emitted per total molecules reacting) is approximately 0.1% to 10% for chemiluminescence and 10% to 30% for bioluminescence. 

Chemiluminescence and bioluminescence are defined as processes in which light is generated during chemical or biological reactions, i.e., exothermic reactions in which part of the reaction energy is converted into photons. In chemiluminescence, an educt molecule is converted to the final stable product upon decay of an unstable chemical intermediate that only exists in an excited electronic state [160, 161]. Bioluminescence includes reactions of photoproteins such as aequorin and of enzymes such as the luciferases (see below). 

We have developed a highly sensitive simultaneous bioluminescent assay of firefly luciferase and aequorin. Firefly luciferin-luciferase reaction is specific and sensitive for the determination of ATP, and this reaction has been widely used, e.g. for hygiene monitoring. Aequorin bounds specifically to Ca and then emits blue light, thus aequorin is useful to study intercellular We thought that these photoproteins... 

Aequorin is a photoprotein isolated from the bioluminescent jellyfish Ae-quorea victoria. Upon addition of calcium ions (Ca2+) and coelenterazine, a reaction occurs whose end result is the generation of blue light in the 460-470 nm range. 

Hori K, Anderson JM, Ward WW, Cormier MJ. Renilla luciferin as the substrate for calcium induced photoprotein bioluminescence. Assignment of luciferin tautomers in aequorin and mnemiopsin. Biochemistry 1975 14 2371-2376. 

Aequorin Aequorea aequorea (Cnidaria) Photoprotein Indicator of bioluminescence (microdetermination of calcium) 224/1 mg... 

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