The scorpion toxin BeKm-1 is unique among a variety of known short scorpion toxins affecting potassium channels in its selective
action on ether-a-go-go-related gene (ERG)-type channels. BeKm-1 ...shares the common molecular scaffold with other short scorpion
toxins. The toxin spatial structure resolved by NMR consists of a short α-helix and a triple-stranded antiparallel β-sheet.
By toxin mutagenesis study we identified the residues that are important for the binding of BeKm-1 to the human ERG K + (HERG) channel. The most critical residues (Tyr-11, Lys-18, Arg-20, Lys-23) are located in the α-helix and following loop
whereas the âtraditionalâ functional site of other short scorpion toxins is formed by residues from the β-sheet. Thus the
unique location of the binding site of BeKm-1 provides its specificity toward the HERG channel.
The isolation of the peptide inhibitor of M-type K+ current, BeKm-1, from the venom of the Central Asian scorpion Buthus eupeus has been described previously (Fillipov A. K., Kozlov, S. A., ...Pluzhnikov, K. A., Grishin, E. V., and Brown, D. A. (1996) FEBS Lett. 384, 277–280). Here we report the cloning, expression, and selectivity of BeKm-1. A full-length cDNA of 365 nucleotides encoding the precursor of BeKm-1 was isolated using the rapid amplification of cDNA ends polymerase chain reaction technique from mRNA obtained from scorpion telsons. Sequence analysis of the cDNA revealed that the precursor contains a signal peptide of 21 amino acid residues. The mature toxin consists of 36 amino acid residues. BeKm-1 belongs to the family of scorpion venom potassium channel blockers and represents a new subgroup of these toxins. The recombinant BeKm-1 was produced as a Protein A fusion product in the periplasm of Escherichia coli. After cleavage and high performance liquid chromatography purification, recombinant BeKm-1 displayed the same properties as the native toxin. Three BeKm-1 mutants (R27K, F32K, and R27K/F32K) were generated, purified, and characterized. Recombinant wild-type BeKm-1 and the three mutants partly inhibited the native M-like current in NG108-15 at 100 nm. The effect of the recombinant BeKm-1 on different K+ channels was also studied. BeKm-1 inhibited hERG1 channels with an IC50 of 3.3 nm, but had no effect at 100 nm on hEAG, hSK1, rSK2, hIK, hBK, KCNQ1/KCNE1, KCNQ2/KCNQ3, KCNQ4 channels, and minimal effect on rELK1. Thus, BeKm-1 was shown to be a novel specific blocker of hERG1 potassium channels.
AF276623
Molecular modeling and subsequent synthesis of novel Syk-kinase inhibitors, 7H-pyrrolo2,3-dpyrimidine and 1,3,5-triazine derivatives, have been carried out. The best of the obtained compounds ...demonstrated to inhibit Syk-kinase activity at IC50 = 230±10 nM
A set of novel fragment-like catechol derivatives were identified as EphA2 inhibitors and were further profiled against a panel of 19 tyrosine kinases. In addition to EphA2, the recovered hits were ...active against EGFR, FGFR1, FGFR2, Abl and PDGFR-a, and according to molecular modelling studies catechol moiety was capable of forming two or more correlated hydrogen bonds with the kinase hinge region, suggesting prospects of its further optimization as an EphA2 inhibitor.
Novel rationally-designed Syk-kinase inhibitor MT-SYK-03 demonstrated equal potency with R406 (active metabolite of Fostamatinib, a phase III clinical trial candidate) in cellular models of ...autoimmunity and cancer with EC50 values in sub-micromolar range, while MT-SYK-322 was less active.
A 30-residue antimicrobial peptide Ar-AMP with six cysteine residues was isolated from the seeds of amaranth
Amaranthus retroflexus L. In spite of the fact that seeds were collected in 1967 and lost ...their germination capacity, Ar-AMP retained its biological activities.
A 30-residue antimicrobial peptide Ar-AMP was isolated from the seeds of amaranth
Amaranthus retroflexus L. essentially by a single step procedure using reversed-phase HPLC, and its in vitro biological activities were studied. The complete amino acid sequence of Ar-AMP was determined by Edman degradation in combination with mass spectrometric methods. In addition, the cDNA encoding Ar-AMP was obtained and sequenced. The cDNA encodes a precursor protein consisting of the N-terminal putative signal sequence of 25 amino acids, a mature peptide of 30 amino acids and a 34-residue long C-terminal region cleaved during post-translational processing. According to sequence similarity the Ar-AMP belongs to the hevein-like family of antimicrobial peptides with six cysteine residues. In spite of the fact that seeds were collected in 1967 and lost their germination capacity, Ar-AMP retained its biological activities. It effectively inhibited the growth of different fungi tested:
Fusarium culmorium (Smith) Sacc.,
Helminthosporium sativum Pammel., King et Bakke,
Alternaria consortiale Fr., and
Botrytis cinerea Pers., caused morphological changes in
Rhizoctonia solani Kühn at micromolar concentrations and protected barley seedlings from
H. sativum infection.
A potentially implantable biocathode with the function of charge accumulation based on a nanobiocomposite including multiwall carbon nanotubes, polyaniline, and bilirubin oxidase is developed. The ...regularities of the functioning of the obtained electrode are studied in air–saturated phosphate buffer solution, pH 7.4 (PB), and also in phosphate buffer solution containing redox–active blood components (BMB). The open circuit potential of the biocathode is 0.33 and 0.08 V vs. the saturated calomel electrode in PB and BMB, respectively; it is completely restored after at least three self-charge/discharge cycles with connection to resistors with different resistance. Bioelectrocatalytic current density of oxygen reduction is 0.50 and 0.42 mA cm
–2
with the residual activity of 78 and 60% of the initial value after 12 h of continuous operation in PB at 25°C and in BMB at 37°C, respectively.
We have developed and synthesized nanobiocomposite materials based on graphene, poly(3,4-ethylenedioxythiophene), and glucose oxidase immobilized on the surface of various nanomaterials (gold ...nanoparticles and multi-walled carbon nanotubes) of different sizes (carbon nanotubes of different diameters). Comparative studies of the possible influence of the nanomaterial's nature on the bioelectrocatalytic characteristics of glucose- oxidizing bioanodes in a neutral phosphate buffer solution demonstrated that the bioelectrocatalytic current densities of nanocomposite-based bioanodes are only weakly dependent on the size of the nanomaterial and are primarily defined by its nature. The developed nanobiocomposites are promising materials for new bioelectronic devices due to the ease in adjusting their capacitive and bioelectrocatalytic characteristics, which allows one to use them for the production of dual-function electrodes: i.e., electrodes which are capable of generating and storing electric power simultaneously.
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