Several derivatives of d
-
mannitol were used in the Ritter reaction with adamantan-1-ol. The reaction with (2
S
,3
S
,4
S
,5
S
)-2,3,4,5-tetraacetoxy-1,6-(cyanosulfanyl)hexane resulted in the ...exclusive isolation of 1,4-di(adamantan-yl) benzene. The reaction of (4
S
,5
S
,6
S
,7
S
)-4,7-bis(cyanosulfanyl)methyl-5,6-dibenzoyloxy-1,3-dioxepane with adamantan-1-ol in sulfuric acid gave (1
S
,2
S
)-1,2-bis(5
S
)-2-(adamantan-ylimino)-1,3-oxathiolan-5-ylethane-1,2-diyl dibenzoate.
Ethyl 2-(4-methyl-6-oxo-1,6-dihydropyrimidin-2-yl)sulfanylacetate reacted with aliphatic amines to give the corresponding acetamides, whereas its reactions with hydrazine hydrate and aniline afforded ...2-hydrazinyl- and 2-anilino-6-methylpyrimidin-4(3
H
)-ones, respectively.
Zika virus (ZIKV) serine protease, indispensable for viral polyprotein processing and replication, is composed of the membrane-anchored NS2B polypeptide and the N-terminal domain of the NS3 ...polypeptide (NS3pro). The C-terminal domain of the NS3 polypeptide (NS3hel) is necessary for helicase activity and contains an ATP-binding site. We discovered that ZIKV NS2B-NS3pro binds single-stranded RNA with a Kd of ~0.3 μM, suggesting a novel function. We tested various structural modifications of NS2B-NS3pro and observed that constructs stabilized in the recently discovered "super-open" conformation do not bind RNA. Likewise, stabilizing NS2B-NS3pro in the "closed" (proteolytically active) conformation using substrate inhibitors abolished RNA binding. We posit that RNA binding occurs when ZIKV NS2B-NS3pro adopts the "open" conformation, which we modeled using highly homologous dengue NS2B-NS3pro crystallized in the open conformation. We identified two positively charged fork-like structures present only in the open conformation of NS3pro. These forks are conserved across Flaviviridae family and could be aligned with the positively charged grove on NS3hel, providing a contiguous binding surface for the negative RNA strand exiting helicase. We propose a "reverse inchworm" model for a tightly intertwined NS2B-NS3 helicase-protease machinery, which suggests that NS2B-NS3pro cycles between open and super-open conformations to bind and release RNA enabling long-range NS3hel processivity. The transition to the closed conformation, likely induced by the substrate, enables the classical protease activity of NS2B-NS3pro.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The recent re-emergence of Zika virus (ZIKV)1, a member of the Flaviviridae family, has become a global emergency. Currently, there are no effective methods of preventing or treating ZIKV infection, ...which causes severe neuroimmunopathology and is particularly harmful to the developing fetuses of infected pregnant women. However, the pathology induced by ZIKV is unique among flaviviruses, and knowledge of the biology of other family members cannot easily be extrapolated to ZIKV. Thus, structure-function studies of ZIKV proteins are urgently needed to facilitate the development of effective preventative and therapeutic agents. Like other flaviviruses, ZIKV expresses an NS2B-NS3 protease, which consists of the NS2B cofactor and the NS3 protease domain and is essential for cleavage of the ZIKV polyprotein precursor and generation of fully functional viral proteins. Here, we report the enzymatic characterization of ZIKV protease, and we identify structural scaffolds for allosteric small-molecule inhibitors of this protease. Molecular modeling of the protease-inhibitor complexes suggests that these compounds bind to the druggable cavity in the NS2B-NS3 protease interface and affect productive interactions of the protease domain with its cofactor. The most potent compound demonstrated efficient inhibition of ZIKV propagation in vitro in human fetal neural progenitor cells and in vivo in SJL mice. The inhibitory scaffolds could be further developed into valuable research reagents and, ultimately, provide a roadmap for the selection of efficient inhibitors of ZIKV infection.
•We report the enzymatic characterization of ZIKV NS2B-NS3 protease.•We identify structural scaffolds for allosteric small-molecule inhibitors of NS2B-NS3.•Inhibitors bind to the druggable cavity in the NS2B-NS3 protease interface.•Inhibitors affect interactions of the protease domain with its cofactor.•The best compound inhibits ZIKV propagation in vitro in human neural progenitors and in vivo in SJL mice.
S
-(2-Thiocyanatopropyl)
N
-alkyl-
N
-methylcarbamothioates were synthesized from
N
-alkyl-1,3-oxathiolan-2-imines by reaction with potassium thiocyanate, and their reactions with alcohols under the ...Ritter conditions afforded 4-substituted
N
-alkyl-1,3-dithiolan-2-imines.
•Immediately after the laser texturing both Cu2O and CuO are present on the surface.•Immediately after fabrication the laser textured surface is hydrophilic.•Laser fluence affects the nanotexture of ...fabricated surface.
Nowadays the problem of design of durable ecologically friendly superhydrophobic surfaces is of great importance for science and technology. A recent paper in Applied Surface Science reports the method of fabricating the superhydrophobic metallic surfaces by infrared nanosecond laser surface texturing without using hydrophobic agents. Since this method of surface texturing can be considered as one of the most suitable for various industrial applications, the nature of superhydrophobic state of surfaces produced by laser texturing in the abovementioned paper deserves to be analyzed in detail. Authors of the commented paper attributed the change in wettability to the partial deoxidation of CuO into Cu2O on the surface during storage in atmosphere. However, such interpretation of the results contradicts to the basic notions in the theory of wetting and to more accurate and detailed data. In our Comment we discuss these contradictions point by point.
—
The surface oscillations of a two-layer drop of an ideal liquid are analyzed. It is shown that two different oscillation frequencies of the taken mode can exist. The effect of the main parameters ...of the liquids that compose the drop on the mode oscillation eigenfrequencies is analyzed. It is found that a relative decrease in the outer liquid layer thickness leads to a decrease in the eigenfrequencies of both in-phase and out-of-phase oscillations. An increase in the difference between the surface tension coefficients leads to an increase in the eigenfrequencies. Relative increase in the inner liquid density increases the eigenfrequencies of the in-phase mode and affects only slightly the eigenfrequencies of the out-of-phase mode. Simplified expressions for the dependences of the eigenfrequencies of oscillating free surface of a compound drop on parameters are obtained.
Myelinating Schwann cells (mSCs) form myelin in the peripheral nervous system. Because of the works by us and others, matrix metalloproteinase-9 (MMP-9) has recently emerged as an essential component ...of the Schwann cell signaling network during sciatic nerve regeneration.
In the present study, using the genome-wide transcriptional profiling of normal and injured sciatic nerves in mice followed by extensive bioinformatics analyses of the data, we determined that an endogenous, specific MMP-9 inhibitor tissue inhibitor of metalloproteinases (TIMP)-1 was a top up-regulated gene in the injured nerve. MMP-9 capture followed by gelatin zymography and Western blotting of the isolated samples revealed the presence of the MMP-9/TIMP-1 heterodimers and the activated MMP-9 enzyme in the injured nerve within the first 24 h post-injury. MMP-9 and TIMP-1 co-localized in mSCs. Knockout of the MMP-9 gene in mice resulted in elevated numbers of de-differentiated/immature mSCs in the damaged nerve. Our comparative studies using MMP-9 knockout and wild-type mice documented an aberrantly enhanced proliferative activity and, accordingly, an increased number of post-mitotic Schwann cells, short internodes and additional nodal abnormalities in remyelinated nerves of MMP-9 knockout mice. These data imply that during the first days post-injury MMP-9 exhibits a functionally important anti-mitogenic activity in the wild-type mice. Pharmacological inhibition of MMP activity suppressed the expression of Na(v)1.7/1.8 channels in the crushed nerves.
Collectively, our data established an essential role of the MMP-9/TIMP-1 axis in guiding the mSC differentiation and the molecular assembly of myelin domains in the course of the nerve repair process. Our findings of the MMP-dependent regulation of Na(v) channels, which we document here for the first time, provide a basis for therapeutic intervention in sensorimotor pathologies and pain.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Ultrafine 5 nm ceria isotropic nanoparticles were prepared using the rapid chemical precipitation approach from cerium(III) nitrate and ammonium hydroxide aqueous solutions. The as-prepared ...nanoparticles were shown to contain predominantly Ce(IV) species. The solubility of nanocrystalline CeO2 at several pH values was determined using ICP-MS and radioactive tracer methods. Phase composition of the ceria samples remained unchanged upon partial dissolution, while the shape of the particles changed dramatically, yielding nanorods under neutral pH conditions. According to X-ray absorption spectroscopy investigation of the supernatant, Ce(III) was the main cerium species in solution at pH < 4. Based on the results obtained, a reductive dissolution model was used for data interpretation. According to this model, the solubility product for ceria nanoparticles was determined to be log K sp = −59.3 ± 0.3 in 0.01 M NaClO4. Taken together, our results show that the pH dependence of ceria anti- and pro-oxidant activity can be related to the dissolution of CeO2 in aqueous media.
A strategy for rational design of synergetic hybrid materials exploiting stabilization of intercalated layered matrices via coordination bonding is described. A new hybrid material is assembled ...through subsequent intercalation of the surface‐anchored metal–organic framework (SURMOF) components, zinc acetate and 5,10,15,20‐tetrakis(4‐carboxyphenyl)‐porphyrin‐zinc(II) (ZnTCPP), into the layered europium(III) hydroxychloride (LEuH). The formation of the SURMOF clusters intercalated in LEuH is confirmed by X‐ray diffraction, FTIR and Raman spectroscopy, and BET nitrogen absorption methods. The catalytic function of the SURMOF/LEuH hybrid and its components in the model reaction of hydrolysis of bis(4‐nitrophenyl) phosphate in the acidic solution is studied by UV–vis and MALDI‐TOF spectroscopy. Both the non‐intercalated matrix and the MOF powder are inactive and unstable in the substrate solution. Unlike its components, the SURMOF/LEuH hybrid exhibits synergetic catalytic activity increasing with the amount of the intercalated compounds because of the mutual stabilization of the components through coordination interactions. The results provide a basis for symbimetic (mimicking the symbiotic behavior in biological systems) hybrid materials, in which stabilization of functional units in the intercalated structure translates into a synergy of useful properties.
A novel approach to create functional intercalated materials exploits stabilizing coordination bonding between porphyrin‐based surface‐anchored metal–organic framework and layered Eu(III) hydroxide. Due to this mutual protection, the layered symbimetic hybrid mimics the behavior of biological symbiotic organisms capable of catalytic “digesting” of potentially harmful organic substrates and surviving in aggressive acidic environments.
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