Combinatorial Chemistry & High Throughput Screening - Volume 18, Issue 10, 2015

Bioluminescent proteins have been intensively used as high sensitive reporters in all kinds of binding assays (immuno-, nucleic acid hybridization assays, etc.) and in bioimaging. But natural luciferases do not always meet the requirements set for them as the assay reporters: thermostabitity, definite bioluminescence spectral and kinetics characteristics, stability to chemical modifications, etc. Luciferases with different appropriate characteristics as well as various luciferin derivatives were obtained using mutagenesis and chemical synthesis. Thanks to rigorous efforts of many researchers bioluminescencebased analytical techniques offer a great potential for solving analytical tasks in the field of biotechnology, biomedicine, pharmacology, etc.

Multiplex simultaneous genotyping technique was developed for four polymorphisms in genes coding for blood coagulation factors and homocysteine metabolism which are considered as thrombophilia related mutations: FV Leiden, FII G20210A, MTHFR C677T, and FVII G10976A. It is based on primer extension reaction with the following bioluminescent solid-phase microassay. At that, two different in bioluminescence obelin mutants were applied to simultaneous detection of two gene allelic variants. The assay is carried out in microtiter plate format and provides fast and reliable genotyping of four single nucleotide polymorphisms in four different genes within 2.5 hours. A large number of clinical samples were analyzed and the obtained results were found to be in complete correlation with those obtained by using conventional RT-PCR techniques.

Multicolor luciferase reporter assays are powerful tools for simultaneously monitoring the expression of several genes. Dual-color luciferase reporter assays were established in 2004 and have been used in broad range of application from basic researches to applications in clinical research, e.g., drug screening and alternative toxicological tests. The advantage of this method is that it can be used to simultaneously monitor sequential and complex changes in the expression of multiple genes from the single-cell level to the tissue level. In this review, I focus on the simultaneous analysis of multiple genes using multicolor beetle luciferases.

Bioanalytical systems based on the Bioluminescence Resonance Energy Transfer (BRET) are widely used in fundamental biochemical studies, as well as for screening and analysis of biologically active compounds. The Renilla luciferase is the most often used energy donor in this system despite the fact that it has low bioluminescence quantum yield and demonstrates not so stable luminescence in time as the firefly luciferase. Moreover, the bioluminescence λmax is observed in the green region of the spectrum, which complicates signal recording in tissues during in vivo experiments. The firefly luciferases do not have such drawbacks and show great promise for applications in BRET systems. Different versions of BRET systems based on firefly luciferases and the methods for increasing their efficiency are considered in this review; examples of the use of BRET systems based on the firefly luciferases for highly sensitive determination of proteases and for homogeneous immunoassays are presented.

This review describes the principle and applications of bioluminescent enzymatic toxicity bioassays. This type of assays uses bacterial coupled enzyme systems: NADH:FMN-oxidoreductase and luciferase to replace living organisms in developing cost-competitive biosensors for environmental, medical and industrial applications. These biosensors instantly signal chemical and biological hazards and allow for detecting a great amount of toxic compounds with advantages associated with fast results, high sensitivity, simplicity, low cost and safety of the procedure.

A series of benzo[a]pyrano[2,3-c]phenazine derivatives with a wide range of substitutions at ring C of the benzophenazine were designed and synthesized using the one-pot, four-component domino reactions. The targeted compounds were evaluated for their antitumor activities against HCT116, MCF7, HepG2 and A549 cancer cell lines in vitro. The most active compound 6{1,2,1,9} featured the CN and p-dimethylamino phenyl substituents on γ-pyran structure on ring C. Significantly, compound 6{1,2,1,9} was found to have the highest growth inhibitory activity against the HepG2 cell line with IC50 values of 6.71 µM, which was 1.6-fold more potent than positive control anticancer drug Hydroxycamptothecine (HCPT). Furthermore, structure-activity relationship (SAR) studies on the substitutions at ring C were discussed in details.

Pyruvate ferredoxin oxidoreductase is the crucial enzyme that involves in bioethanol synthesis pathway of Clostridium thermocellum. It is an ethanologenic organism but has been investigated less on its enzyme structure. The amino acid sequence of Pyruvate ferredoxin oxidoreductase was derived from UNIPROT and the screened crystal structure was taken as the template for homology modeling using MODELLER 9V11. The model was loop refined and was validated using RMSD, ProSA and PROCHECK. The docking and per residue interaction studies were carried out to elucidate the interaction energies of amino acid residues with pyruvate. To enhance the binding of pyruvate with the enzyme, mutation studies were carried out by replacing Thr31 as it had a less interaction energy. Out of 10 mutants, T31N, T31Q and T31G were selected using potential energy and the residual energy calculations. Five nanoseconds explicit MD simulations were run for apo, wild type and mutants T31N, T31Q and T31G using Desmond. RMSD, RMSF, distance plots and H-bonds analysis proved T31G to be a favorable mutant for binding of pyruvate. Thus, modeling PFOR would help in profound understanding of its structural clefts and mutation studies would aid in improving the enzyme efficiency.

(7S, 14S, 16R)- dialkyl 6-oxo-6,7,13,14-tetrahydro-7,14-methanobenzo[d]chromeno[3,4- h][1,6,3]oxathiazo-nine-14,16-dicarboxylates 4 and (S)-methyl 2-(2-methoxy-2-oxoethyl)-2,3- dihydrobenzo[d]thiazole-2-carboxylates 5 were readily synthesized in a ratio 3:1 and moderated yield by multicomponent reactions of 4-hydroxycoumarin and acetylenic esters with benzothiazole without using a catalyst. Also, The GIAO/DFT approach at the B3LYP/6-31G** level of theory was used to calculate the 1H, 15N, 17O and 13C NMR chemical shifts of product 4b. These computations are performed on the basis of X-ray structural data which are collected at 120(2) K temperature. In order to take into account intermolecular hydrogen bonds and the van der Waals effects, two different sizes of clusters (two model of trimeric and pentameric clusters) have been considered. A comparison between the experimental (Exp.) and calculated (Cal.) 1H and 13C NMR chemical shifts may reveal that the solution contains monomer, trimer1, trimer2, and pentamer models.