Synthesis of two Hofmann type and Hofmann-type-like compounds in crystal form from 4-aminopyridine and their characterizations by various methods

A detailed understanding of the mechanism of protein synthesis will ultimately depend on knowledge of the native structure of the ribosome. Towards this end we have investigated the low resolution structure of the eukaryotic ribosome embedded in frozen buffer, making use of a system in which the ribosomes crystallize naturally.The ribosomes in the cells of early chicken embryos form crystalline arrays when the embryos are cooled at 4°C. We have developed methods to isolate the stable unit of these arrays, the ribosome tetramer, and have determined conditions for the growth of two-dimensional crystals in vitro, Analysis of the proteins in the crystals by 2-D gel electrophoresis demonstrates the presence of all ribosomal proteins normally found in polysomes. There are in addition, four proteins which may facilitate crystallization. The crystals are built from two oppositely facing P4 layers and the predominant crystal form, accounting for >80% of the crystals, has the tetragonal space group P4212, X-ray diffraction of crystal pellets demonstrates that crystalline order extends to ~ 60Å.

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A Possible Basis for Nondestructive Characterization of Ropes of Nylon 6

MRS Proceedings ◽

10.1557/proc-503-243 ◽

1997 ◽

Vol 503 ◽

Author(s):

H. Jiang ◽

M. K. Davis ◽

R. K. Eby ◽

P. Arsenovic

Keyword(s):

Tensile Strength ◽

Service Life ◽

Fiber Diameter ◽

Structural Parameters ◽

Crystal Form ◽

Nylon 6 ◽

Remaining Service Life ◽

Nondestructive Characterization ◽

Fractional Content

ABSTRACTPhysical properties and structural parameters have been measured for ropes of nylon 6 as a function of the number of use operations. The fractional content of the α crystal form, sound velocity, birefringence, tensile strength and length all increase systematically and significantly with increasing the number of use operations. The fractional content of the γ crystal form and fiber diameter decrease with use. These trends indicate that the measurement of such properties and structural parameters, especially the length, provide a possible basis for establishing a reliable, rapid, and convenient nondestructive characterization method to predict the remaining service life of nylon 6 ropes.

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Functional characterization and structural modelling of peptidoglycan degrading β-N-acetyl-glucosaminidase from a dental isolate of Serratia marcescens

Combinatorial Chemistry & High Throughput Screening ◽

10.2174/1386207323999201103204234 ◽

2020 ◽

Vol 23 ◽

Author(s):

Aditi Rathee ◽

Anil Panwar ◽

Seema Kumari ◽

Sanjay Chhibber ◽

Ashok Kumar

Keyword(s):

Functional Characterization ◽

Major Change ◽

Crystal Form ◽

Bound State ◽

Dynamics Simulation ◽

Gram Positive ◽

Structural Cell ◽

Stability Structure ◽

Arginine Residues ◽

The Stability

Introduction:: Enzymatic degradation of peptidoglycan, a structural cell wall component of Gram-positive bacteria, has attracted considerable attention being a specific target for many known antibiotics. Methods:: Peptidoglycan hydrolases are involved in bacterial lysis through peptidoglycan degradation. β-N-acetylglucosaminidase, a peptidoglycan hydrolase, acts on O-glycosidic bonds formed by N-acetylglucosamine and N-acetyl muramic acid residues of peptidoglycan. Aim of present study was to study the action of β-N-acetylglucosaminidase, on methicillin- resistant Staphylococcus aureus (MRSA) and other Gram-negative bacteria. Results:: We investigated its dynamic behaviour using molecular dynamics simulation and observed that serine and alanine residues are involved in catalytic reaction in addition to aspartic acid, histidine, lysine and arginine residues. When simulated in its bound state, the RMSD values were found lesser than crystal form in the time stamp of 1000 picoseconds revealing its stability. Structure remained stably folded over 1000 picoseconds without undergoing any major change further confirming the stability of complex. Conclusion:: It can be concluded that enzymes belonging to this category can serve as a tool in eradicating Gram-positive pathogens and associated infections.

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Effects of Sources and Forms of Vitamin K3 on Its Storage Stability in Vitamin Premixes or Vitamin Trace Mineral Premixes

Animals ◽

10.3390/ani11041140 ◽

2021 ◽

Vol 11 (4) ◽

pp. 1140

Author(s):

Huakai Wang ◽

Pan Yang ◽

Longxian Li ◽

Nan Zhang ◽

Yongxi Ma ◽

...

Keyword(s):

Relative Humidity ◽

Storage Time ◽

Storage Stability ◽

Choline Chloride ◽

Crystal Form ◽

Negative Effects ◽

Trace Mineral ◽

Vitamin K3 ◽

Choline Group ◽

Micro Sphere

Six types of vitamin K3 (VK3); two sources (menadione sodium bisulfite, MSB; menadione nicotinamide bisulfite, MNB), and three different forms (crystal, micro-capsule, and micro-sphere) were used to determine the retention of VK3 in vitamin premixes (Experiment 1) or vitamin trace mineral (VTM) premixes (Experiment 2) after 1, 2, 3, and 6 months of storage. The retention of VK3 in vitamin premixes was evaluated at 25 °C/60% relative humidity or 40 °C/75% relative humidity in an incubator in Experiment 1 and in VTM premixes (choline chloride: 0 vs. 16,000 mg/kg) stored at room temperature in Experiment 2. The VK3 retention in vitamin premix or VTM premix decreased significantly with the extension of storage time (p < 0.05). In Experiment 1, the VK3 retention was higher in the 25 °C/60% incubator (56%) than in the 40 °C/75% incubator (28%). The MNB retention (52%) was higher than MSB retention (32%). The retention of VK3 in micro-capsules (43%) or micro-spheres (48%) was higher than the crystal form (35%) after six months of storage. In Experiment 2, there was no difference between the retention of MSB (49%) or MNB (47%). The retention of VK3 of micro-capsule (51%) or micro-sphere (54%) was higher than that of crystal form (40%). The VK3 retention was higher in the choline-free group (51%) than in the choline group (47%) after six months of storage. Finally, the predicted equations of VK3 retention with storage time in vitamin premixes or VTM premixes were established. The R2 of the prediction equations was ≥0.9005, indicating that time is an important factor in predicting VK3 retention. In conclusion, the higher temperature-relative humidity, choline had negative effects on VK3 retention during premix storage. MNB retention was higher than MSB during storage of vitamin premix. The encapsulated forms of VK3, micro-capsules and micro-spheres, could improve VK3 storage stability in vitamin premix and VTM premix.

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Applications of Supercritical Anti-Solvent Process in Preparation of Solid Multicomponent Systems

Pharmaceutics ◽

10.3390/pharmaceutics13040475 ◽

2021 ◽

Vol 13 (4) ◽

pp. 475

Author(s):

Guijin Liu ◽

Junjian Li ◽

Shiming Deng

Keyword(s):

Solid State ◽

Solid Dispersions ◽

Crystal Form ◽

Great Promise ◽

Computational Techniques ◽

Large Contribution ◽

Continuous Manufacturing ◽

Multicomponent Systems ◽

On Line ◽

Underlying Mechanisms

Solid multicomponent systems (SMS) are gaining an increasingly important role in the pharmaceutical industry, to improve the physicochemical properties of active pharmaceutical ingredients (APIs). In recent years, various processes have been employed for SMS manufacturing. Control of the particle solid-state properties, such as size, morphology, and crystal form is required to optimize the SMS formulation. By utilizing the unique and tunable properties of supercritical fluids, supercritical anti-solvent (SAS) process holds great promise for the manipulation of the solid-state properties of APIs. The SAS techniques have been developed from batch to continuous mode. Their applications in SMS preparation are summarized in this review. Many pharmaceutical co-crystals and solid dispersions have been successfully produced via the SAS process, where the solid-state properties of APIs can be well designed by controlling the operating parameters. The underlying mechanisms on the manipulation of solid-state properties are discussed, with the help of on-line monitoring and computational techniques. With continuous researching, SAS process will give a large contribution to the scalable and continuous manufacturing of desired SMS in the near future.

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Tunable photoluminescence properties of microcrystalline cellulose with gradually changing crystallinity and crystal form

Macromolecular Rapid Communications ◽

10.1002/marc.202100321 ◽

2021 ◽

pp. 2100321

Author(s):

Jiantang Jiang ◽

Shijia Lu ◽

Man Liu ◽

Chuchu Li ◽

Yuanchao Zhang ◽

...

Keyword(s):

Microcrystalline Cellulose ◽

Crystal Form ◽

Photoluminescence Properties

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Interfacial Compatibility on the Crystal Transformation of Isotactic Poly (1-Butene)/Herb Residue Composite

Polymers ◽

10.3390/polym13101654 ◽

2021 ◽

Vol 13 (10) ◽

pp. 1654

Author(s):

Bo Wang ◽

Shuangdan Mao ◽

Fuhua Lin ◽

Mi Zhang ◽

Yuying Zhao ◽

...

Keyword(s):

Beneficial Effect ◽

Crystal Form ◽

Spontaneous Transformation ◽

Water Contact ◽

Crystal Transformation ◽

Transformation Time ◽

Organic Functional Groups ◽

Silane Coupling ◽

Interfacial Compatibility ◽

Thermal Stability Of

Isotactic poly (1-butene) (iPB) has excellent properties which are recognized as a green and energy saving product. However, the most stable and valuable crystal form I had a spontaneous transformation that took as long as seven days to complete. As a special solid waste, the herb residue (HR) is rich in cellulose which has great potential to accelerate the crystal transformation of the iPB. However, the polarity of HR results in the interface compatibility with non-polar iPB. In this study, the HR was modified by silane coupling agent (KH570) to obtain KHR and the iPB/HR composite was prepared. The FTIR spectrum was indicated that the organic functional groups of KH570 successfully graft onto the surface of HR and the water contact angle test was indicated that the hydrophilicity of the KHR was greatly decreased. The complete crystal transformation time is 7 days for iPB, 6 days for iPB+5% HR but only 3 days for iPB+5% KHR. The addition of the HR and KHR improve the thermal stability of the composite and this beneficial effect is more obvious for KHR. After annealing for 5 days, the physical properties value include tensile strength, flexural strength, and HDT of iPB+5% HR reach that of pure iPB after annealing for 7 days, but only 3 days for iPB+5% KHR. The TG analysis and SEM photographs give clear evidence that the beneficial effect of KH570 modified HR on improving the interface compatibility with iPB.

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Single-crystalline epitaxial TiO film: A metal and superconductor, similar to Ti metal

Science Advances ◽

10.1126/sciadv.abd4248 ◽

2021 ◽

Vol 7 (2) ◽

pp. eabd4248

Author(s):

Fengmiao Li ◽

Yuting Zou ◽

Myung-Geun Han ◽

Kateryna Foyevtsova ◽

Hyungki Shin ◽

...

Keyword(s):

Transition Metal ◽

Density Functional ◽

Tight Binding ◽

Crystal Form ◽

Titanium Monoxide ◽

Binding Model ◽

Functional Theory ◽

Single Crystalline ◽

First Time ◽

Lattice Matched

Titanium monoxide (TiO), an important member of the rock salt 3d transition-metal monoxides, has not been studied in the stoichiometric single-crystal form. It has been challenging to prepare stoichiometric TiO due to the highly reactive Ti2+. We adapt a closely lattice-matched MgO(001) substrate and report the successful growth of single-crystalline TiO(001) film using molecular beam epitaxy. This enables a first-time study of stoichiometric TiO thin films, showing that TiO is metal but in proximity to Mott insulating state. We observe a transition to the superconducting phase below 0.5 K close to that of Ti metal. Density functional theory (DFT) and a DFT-based tight-binding model demonstrate the extreme importance of direct Ti–Ti bonding in TiO, suggesting that similar superconductivity exists in TiO and Ti metal. Our work introduces the new concept that TiO behaves more similar to its metal counterpart, distinguishing it from other 3d transition-metal monoxides.

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