Ionization states of the complex formed between 2-benzyl-3-phosphonopropionic acid and carboxypeptidase A.

The binding to carboxypeptidase A of two phosphonic acid analogues of 2-benzylsuccinate, 2-DL-2-benzyl-3-phosphonopropionic acid (inhibitor I) and 2-DL-2-benzyl-3-(-O-ethylphosphono)propionic acid (inhibitor II) was studied by observing their 31P resonances when free and bound to the enzyme in the range of pH from 5 to 10. The binding of I by co-ordination to the active-site Zn(II) lowered the highest pKa of I from a value of 7.66(+/- 0.10) to a value of 6.71(+/- 0.17). No titration of any protons on II occurred over the pH range studied. The enzyme-bound inhibitor II also did not titrate over the pH range 6.17-7.60. The pH-dependencies of the apparent inhibition constants for I and II were also investigated by using N-(-2-(furanacryloyl)-L-phenylalanyl-L-phenylalanine as substrate. Two enzymic functional groups with pKa values of 5.90(+/- 0.06) and 9.79(+/- 0.14) must be protonated for binding of inhibitor I, and two groups with pKa values of 6.29(+/- 0.10) and 9.19(+/- 0.15) for binding of inhibitor II. Over the pH range from 6.71 to 7.66, inhibitor I binds to the enzyme in a complex of the enzyme in a more protonated form, and the inhibitor in a less protonated form than the predominant unligated forms at this pH. Mock & Tsay [(1986) Biochemistry 25, 2920-2927] made a similar finding for the binding of L-2-(1-carboxy-2-phenylethyl)-4-phenylazophenol over a pH range of nearly 4 units. The true inhibition constant for the dianionic form of inhibitor I (racemic) was calculated to be 54.0(+/- 5.9) nM and that of the trianionic form to be 5.92(+/- 0.65) nM. The true inhibition constant of the fully ionized II (racemic) was calculated to be 79.8(+/- 6.4) nM.     

Toxicity,of extracts of barley kernels inoculated withFusarium spp. toArtemia salina

Toxicity toA. salina, of the Fusarium metabolites: deoxynivalenol (DON), its acetylated derivatives (3- and 15-AcDON), zearalenone (ZON), neosolaniol (NEO), nivalenol (NIV), T-2, HT-2 toxins, has been examined and compared with toxicity of extracts of barley kernels (8 cultivars and 4 lines) inoculated withFusarium culmorum, F. graminearum andF. sporotrichioides respectively. Estimated LC₅₀ values were expressed as relative toxicity (RT) in mg DON/kg for samples inoculated withF. culmorum, F. graminearum or in mg T-2/kg forF. sporotrichioides inoculations. Toxicity of extracts of the same genotype/line kernels was compared among different pathogens used for inoculation and differences in Fusarium head blight susceptibility of different genotypes/lines inoculated with the sameFusarium strain were found. Significant correlation between toxicity of extracts (LC₅₀, RT) and toxic metabolites concentration was found ( $\bar r = 0.82$ ; P = 0.01). Bioassays withA. Salina offer a fast, easy and inexpensive method to examine cereal genotypes susceptibility to Fusarium head blight and mycotoxins accumulation in kernels.     

Biosynthesis,isolation, purification and seperation of Zearalenone,deoxynivalenol and 15-Acetyldeoxynivalenol

Fusarium graminearum KF-376 isolate was found to be able to form simultaneously three toxic metabolites: zearalenone (FF-2), deoxynivalenol (DON) and 15-acetyldeoxynivalenol (15-AcDON). Toxins were extracted with methanol — water 3:1 (v/v) and purified by liquid chromatography on charcoal — Kieselgel 60 column (preliminary) and Aluminiumoxid 90 column. Final separation of the metabolites was achived on Kieselgel 60 — Aluminiumoxid 90 column.     

Synthesis,characterization, in silico ADMET prediction,and protein binding analysis of a novel zinc(II) Schiff-base complex: Application of multi-spectroscopic and computational techniques

By reaction of 1,2-diaminocyclohexane with the 2,3-butanedione monoxime in the presence of ZnCl₂, a new Schiff base complex was obtained. This complex was characterized by elemental analyses, FT-IR, ¹H NMR, UV–Vis, and conductivity measurements. The reactivity of this complex to human serum albumin (HSA) under simulative physiological conditions was studied by spectroscopic and molecular docking analysis. Experimental results at various temperatures indicated that the intrinsic fluorescence of protein was quenched through a static quenching mechanism. The negative value of enthalpy change and positive value of entropy change indicated that both hydrogen bonding and hydrophobic forces played a major role in the binding of Zn(II) complex to HSA. FT-IR, three-dimensional fluorescence, and UV–Vis absorption results showed that the secondary structure of HSA changed after Zn(II) complex bound to protein. The binding distance was calculated to be 4.96 nm, according to fluorescence resonance energy transfer. Molecular docking results confirmed the spectroscopic results and showed that above complex is embedded into subdomain IIA of protein. All these experimental and computational results clarified that Zn(II) complex could bind with HSA effectively, which could be a useful guideline for efficient Schiff-base drug design.     

Heterobicyclic inhibitors of transforming growth factor beta receptor I (TGFβRI)

The TGFβ-TGFβR signaling pathway has been reported to play a protective role in the later stages of tumorigenesis via increasing immunosuppressive Treg cells and facilitating the epithelial to mesenchymal transition (EMT). Therefore, inhibition of TGFβR has the potential to enhance antitumor immunity. Herein we disclose the identification and optimization of novel heterobicyclic inhibitors of TGFβRI that demonstrate potent inhibition of SMAD phosphorylation. Application of structure-based drug design to the novel pyrrolotriazine chemotype resulted in improved binding affinity (Ki apparent?=?0.14?nM), long residence time (T_1/2?>?120?min) and significantly improved potency in the PSMAD cellular assay (IC₅₀?=?24?nM). Several analogs inhibited phosphorylation of SMAD both in vitro and in vivo. Additionally, inhibition of TGFβ-stimulated phospho-SMAD was observed in primary human T cells.     

Ig-like Domain in Endoglucanase Cel9A from <Emphasis Type="Italic">Alicyclobacillus acidocaldarius</Emphasis> Makes Dependent the Enzyme Stability on Calcium

Endoglucanase Cel9A from Alicyclobacillus acidocaldarius (AaCel9A) has an Ig-like domain and the enzyme stability is dependent to calcium. In this study the effect of calcium on the structure and stability of the wild-type enzyme and the truncated form (the wild-type enzyme without Ig-like domain, AaCel9AΔN) was investigated. Fluorescence quenching results indicated that calcium increased and decreased the rigidity of the wild-type and truncated enzymes, respectively. RMSF results indicated that AaCel9A has two flexible regions (regions A and B) and deleting the Ig-like domain increased the truncated enzyme stability by decreasing the flexibility of region B probably through increasing the hydrogen bonds. Calcium contact map analysis showed that deleting the Ig-like domain decreased the calcium contacting residues and their calcium binding affinities, especially, in region B which has a role in calcium binding site in AaCel9A. Metal depletion and activity recovering as well as stability results showed that the structure and stability of the wild-type and truncated enzymes are completely dependent on and independent of calcium, respectively. Finally, one can conclude that the deletion of Ig-like domain makes AaCel9AΔN independent of calcium via decreasing the flexibility of region B through increasing the hydrogen bonds. This suggests a new role for the Ig-like domain which makes AaCel9A structure dependent on calcium.     

Structural fingerprints,interactions, and signaling networks of RAS family proteins beyond RAS isoforms

Among the signaling molecules indirectly linked to many different cell surface receptors, RAS proteins essentially respond to a diverse range of extracellular cues. They control activities of multiple signaling pathways and consequently a wide array of cellular processes, including survival, growth, adhesion, migration, and differentiation. Any dysregulation of these pathway leads, thus, to cancer, developmental disorders, metabolic, and cardiovascular diseases. The biochemistry of RAS family proteins has become multifaceted since the discovery of the first members, more than 40 years ago. Substantial knowledge has been attained about molecular mechanisms underlying post-translational modification, membrane localization, regulation, and signal transduction through diverse effector molecules. However, the increasing complexity of the underlying signaling mechanisms is considerable, in part due to multiple effector pathways, crosstalks between them and eventually feedback mechanisms. Here, we take a broad view of regulatory and signaling networks of all RAS family proteins that extends beyond RAS paralogs. As described in this review, a lot is known but a lot has to be discovered yet.     

Prevalence of restless legs syndrome in pregnant women: a meta-analysis

Sleep and Biological Rhythms - Restless legs syndrome is a neuromotor problem which is more common among pregnant women. Several studies have reported different prevalences for this disorder....