Semisynthetic Aequorins

The core cavity of the aequorin molecule can accommodate various synthetic analogues of coelenterazine in place of coelenterazine. The replacement of the coelenterazine moiety of aequorin can be 

(Prefix) Structural Modification of Coelenterazine3 Luminescence Max. (nm) Relative Total Light Amountb Relative Intensity in 10 6 or 10 7M Ca2+C Half-total Light Time (s)d 

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Table 4.1.3 Properties of Semisynthetic Aequorins prepared from a single batch of Natural Aequorin measured at 23-25°C (Shimomura, 1991a)... 

Table 4.1.4 Semisynthetic Aequorins derived from Recombinant Aequorin (Shimomura et al., 1993a)... 

Fig. 4.1.14 Relationship between Ca2+ concentration and the initial light intensity of various recombinant semisynthetic aequorins and w-aequorin J (a semisynthetic natural aequorin made from isoform J). The curve number corresponds to the number of semisynthetic aequorin used in Table 4.1.4. A sample aequorin (3 (Ag) was in 3 ml of calcium-buffer solution containing 1 mM total EGTA, 100 mM KC1,1 mM Mg2+ and 1 mM MOPS (pH 7.0), at 23-24°C. From Shimomura etal., 1993a, with permission from Elsevier.

Preparation of semisynthetic aequorins. The best yield of semisynthetic aequorins can be obtained by using the apoaequorin prepared from aequorin immediately before use. Apoaequorin stored, even for 2-3 days, or recombinant apoaequorin isolated from a bacterial culture will give a significantly lower yield due to their somewhat unfolded molecular conformation. Fresh apoaequorin prepared by the Ca2+-triggered luminescence reaction appears to have the conformation best suited for regeneration. 

Hirano, T., et al. (1998). Bioluminescent properties of fluorinated semisynthetic aequorins. Tetrahedron Lett. 39 5541-5544. 

Shimomura, O. (1995d). Cause of spectral variation in the luminescence of semisynthetic aequorins. Biochem. J. 306 537-543. 

Shimomura, O. Musicki, B. Kishi, Y. Semisynthetic aequorin. An improved tool for the measurement of calcium ion concentration. Biochem. J. 1988, 251, 405 10. 

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