Shojiro Maki

Fluorescent properties of model chromophores of tyrosine-66 substituted mutants of Aequorea green fluorescent protein (GEP)

Abstract In an ethanol-glass marix at 77 K, model compounds of the chromophores of recombinant GFP-Y66F, GFP-Y66W, and GEP-Y66H exhibited fluorescence properties close to those of the corresponding mutant proteins.

A luciferin analogue generating near-infrared bioluminescence achieves highly sensitive deep-tissue imaging

In preclinical cancer research, bioluminescence imaging with firefly luciferase and D-luciferin has become a standard to monitor biological processes both in vitro and in vivo. However, the emission maximum (λmax) of bioluminescence produced by D-luciferin is 562 nm where light is not highly penetrable in biological tissues. This emphasizes a need for developing a red-shifted bioluminescence imaging system to improve detection sensitivity of targets in deep tissue. Here we characterize the bioluminescent properties of the newly synthesized luciferin analogue, AkaLumine-HCl. The bioluminescence produced by AkaLumine-HCl in reactions with native firefly luciferase is in the near-infrared wavelength ranges (λmax=677 nm), and yields significantly increased target-detection sensitivity from deep tissues with maximal signals attained at very low concentrations, as compared with D-luciferin and emerging synthetic luciferin CycLuc1. These characteristics offer a more sensitive and accurate method for non-invasive bioluminescence imaging with native firefly luciferase in various animal models.

Bioluminescent properties of fluorinated semi-synthetic aequorins

Abstract Bioluminescent properties of semi-synthetic aequorins containing coelenterazine analogues possessing fluoro group(s) on the 6-(4-hydroxyphenyl) group match the fluorescent behavior of the phenolate anions of the corresponding fluorinated coelenteramide analogues, indicating that the phenolate anion of coelenteramide is the light-emitter in aequorin bioluminescence.

Fluorescence properties of phenolate anions of coelenteramide analogues: the light-emitter structure in aequorin bioluminescence

Abstract To elucidate the ionic structure of the excited state of light-emitter coelenteramide in aequorin bioluminescence, the fluorescent properties of phenolate anions of coelenteramide analogues were investigated. Fluorescence of phenolate anion in non-polar solvents was observed by electronic excitation of a 1:1 hydrogen-bonded complex of a coelenteramide analogue with a hydrogen-bond donor molecule such as n -butylamine. In polar solvents, the phenolate anion was directly generated using a base, and its fluorescence was studied. These results confirm that the singlet-excited state of phenolate anion of coelenteramide has an intramolecular CT character, and that its fluorescence emission wavelength changes depending upon solvent polarity. The fluoro-substituent effect on the fluorescent property of phenolate anions was also clarified to help in explaining the bioluminescent property of fluorinated semi-synthetic aequorin. These results consistently support the assignment that the phenolate anion is the ionic structure of the excited light-emitter in BFP during AQ bioluminescence.

Synthesis of (±)-pentalenene using electrochemical method as a key step

Abstract (±)-Pentalenene has been synthesized from 6-acetoxymethyl-2-methyl-9-methoxytdcycio[5.3.1.0 1,5 ]undec-9-en-8,11-dione which has been produced efficiently by means of electrochemical method.

Bioluminescence characteristics of the fruiting body of Mycena chlorophos.

Bioluminescent fungi are widely distributed on land and most belong to the class Basidomycetes. Light of about 530 nm wavelength maximum is emitted continuously. The molecular basis for the light-emitting process remains unclear. We investigated the characteristics of the bioluminescence using cultivated fruiting bodies of M. chlorophos. Only fresh fruiting bodies exhibited long-lasting light emission; rapid decay of light emission was observed with frozen and freeze-dried samples. Freeze-dried samples can be stored at room temperature under dry conditions and may be useful for the isolation of luciferin. The light emission of the fresh fruiting bodies was maintained in various buffers at varying pH; it could be stopped with pH 4 acetate buffer and could be recovered at pH 6. The isolation of luciferin from the fresh fruiting bodies might be possible by the control of buffer pH. The effect of temperature on the light emission of fruiting bodies indicated that bioluminescence in M. chlorophos may involve enzymatic reaction(s). The solubilization of bioluminescent components from the fruiting bodies could not be achieved with various surfactants.

Spectroscopic studies of the color modulation mechanism of firefly (beetle) bioluminescence with amino-analogs of luciferin and oxyluciferin.

Spectroscopic properties of amino-analogs of luciferin and oxyluciferin were investigated to confirm the color modulation mechanism of firefly (beetle) bioluminescence. Fluorescence solvatochromic character of aminooxyluciferin analogs indicates that the bioluminescence of aminoluciferin is useful for evaluating the polarity of a luciferase active site.

Facile syntheses of some trans-hydroazulenes by means of electrochemical methodology coupled with base-catalyzed fragmentation reaction

Abstract Some phenols with an olefinic side chain have been electrolyzed under various conditions to afford tricyclo[5.3.1.0 1,5 ]undec-9-en-8,11-diones. These products were treated with potassium carbonate in methanol to give rise to the corresponding trans-hydroazulenes which are regarded as a promising synthetic intermediate of bioactive sesqui- and diterpenoids.

Pd black deposited on polypropylene sheet as a highly selective catalyst for hydrogenation of alkenes

A catalyst deposited on a polypropylene sheet having an activity of almost the same level as commercially available Pd black and capable of promoting hydrogenolysis-free hydrogenation was developed.

Effect of solvent and hydrogen during selective hydrogenation

Abstract Described is the solvent effect for the chemoselective hydrogenation of alkenes having a benzyloxy group (Bn-O-) using a hydrogenation system employing atomic hydrogen permeating through a Pd sheet electrode.