BIOLUMINESCENCE FROM THE REACTION OF FMN, H2O2 AND LONG CHAIN ALDEHYDE WITH BACTERIAL LUCIFERASE

Abstract— The bioluminescent oxidation of reduced flavin mononucleotide by bacterial luciferase involves a long-lived flavoenzyme intermediate whose chromophore has been postulated to be the 4a-sub-stituted peroxy anion of reduced flavin. Reaction of long chain aldehyde with this intermediate results in light emission and formation of the corresponding acid. These experiments show that the typical aldehyde-dependent, luciferase-catalyzed bioluminescence can also be obtained starting with FMN and H₂O₂ instead of FMNH₂ and O₂. We postulate that the 4a-peroxy anion intermediate is formed directly by attack of H₂O₂ on FMN. The latter may be bound to luciferase. An enzyme bound intermediate is formed which by kinetic analysis, flavin specificity for luminescence, aldehyde dependence, and bioluminescent emission spectrum appears to be identical with the species generated by reaction of FMNH, and O₂ with luciferase. The quantum yield of the H₂O₂-_- and FMN-initiated biolumlnescence is low but can be enhanced by certain metal ions, which also stimulate a chemiluminescent reaction of oxidized flavin with H₂O₂. The peak of this chemiluminescence. however, appears to be at a shorter wavelength than that (490 nm) of the bioluminescence.     

The147Sm(n,α)144Nd Reaction on 2 keV neutrons

Through (p,2n) in-beam γ and e^? measurements the excitation of the 235 μs 9⁺ isomer in¹⁴⁶Eu has been determined to be 666.3 keV. High spin members of the πd ₅ ^2/?1 νf_7/2 and πg ₇ ^2/?1 νf_7/2 particle hole multiplets populated in the isomeric decay were located.     

A NEW REDUCING AGENT OF FLAVINS AND ITS APPLICATION TO THE ASSAY OF BACTERIAL LUCIFERASE

Copper(I) plus ethylenediaminetetraacetic acid, Cu(I)-EDTA, reduces flavins. Using Cu(I)-EDTA reduction of riboflavin 5'-phosphate, a new assay method for bacterial luciferase is established. In previous assay methods, flavin and aldehyde substrates for luciferase have been routinely added to luciferase at different times; the new assay permits aldehyde and Cu(I)-reduced flavin to be injected simultaneously into air-saturated buffer containing luciferase. In the new assay method using Cu(I), bovine serum albumin is not required, the initial emission intensity is more than twice and the overall yield is about twice of that in the so-called standard assay for luciferase.     

Further indication of a low quartz structure at the SiO2/Si interface from coincidence Doppler broadening spectroscopy

Results from coincidence Doppler broadening (CDB) measurements on various Si samples and Brazilian quartz having low quartz structure are presented with the aim to give further strong indication of the existence of a low quartz structure, but not of Si divacancies as frequently considered, at the SiO₂/Si interface.     

Kinetic study of the reaction of dimethyl carbonate with trialkylamines

Quaternary ammonium compounds are produced worldwide in hundreds of millions of pound volume annually for a plethora of end‐uses from fabric‐care formulations to asphalt emulsifiers, typically from nongreen alkylating reagents. The kinetics of a reaction employing dimethyl carbonate (DMC) as a green alkylating agent was investigated using three trialkylamines (tributylamine, trihexylamine, and trioctylamine) at several temperatures. Arrhenius and Eyring analysis of the data showed that values of E_a (79 kJ/mol), ΔH^? (75 kJ/mol), and ΔS^? (220 J/(mol K)) were the same for all three amine reactants, consistent with a report that E_a is independent of alkyl chain length when the chain length is greater than three carbons. Although rates are significantly slower with DMC than with other alkylating reagents, the resulting methyl carbonate anion has advantages for clean anion metathesis, which is important for some applications, especially those involving ionic liquids. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: 221–225, 2010