The Stability of Angiotensin I Formed at Room Temperature in the Presence of Ethylenediaminetetraacetate to Subsequent Incubation at 37 °C

SummaryAn attempt was made to obtain Ac-globulin from bovine plasma. The concentrates contain mostly protein, and phosphorus is also present. The stability characteristics vary from one preparation to another, but in general there was no loss before 1 month in a deep freeze or before 1 week in an icebox, or before 5 hours at room temperature. Reducing agents destroy the activity rapidly. S-acetylmercaptosuccinic anhydride is an effective stabilizing agent. Greatest stability was at pH 6.0.In the purification bovine plasma is adsorbed with barium carbonate and diluted 6-fold with water. Protein is removed at pH 6.0 and the Ac-globulin is precipitated at pH 5.0. Rivanol and alcohol fractionation is followed by chromatography on Amberlite IRC-50 or DEAE-cellulose. The final product is obtained by isoelectric precipitation.

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Tyrosine-Selective Bioconjugation with Iminoxyl Radicals

10.26434/chemrxiv.12278717 ◽

2020 ◽

Author(s):

Katsuya Maruyama ◽

Takashi Ishiyama ◽

Yohei Seki ◽

Kounosuke Oisaki ◽

Motomu Kanai

Keyword(s):

Reaction Time ◽

Steric Hindrance ◽

Room Temperature ◽

Water Soluble ◽

Light Irradiation ◽

Sodium Ascorbate ◽

Iminoxyl Radical ◽

Short Reaction Time ◽

Modified Peptides ◽

The Stability

A novel Tyr-selective protein bioconjugation using the water-soluble persistent iminoxyl radical is described. The conjugation proceeded with high Tyr-selectivity and short reaction time under biocompatible conditions (room temperature in buffered media under air). The stability of the conjugates was tunable depending on the steric hindrance of iminoxyl. The presence of sodium ascorbate and/or light irradiation promoted traceless deconjugation, restoring the native Tyr structure. The method is applied to the synthesis of a protein-dye conjugate and further derivatization to azobenzene-modified peptides.

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Circular dichroism and infrared study of β-turn formation in repeat peptides of elastin

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19871356 ◽

1987 ◽

Vol 52 (5) ◽

pp. 1356-1361

Author(s):

S. Abdel Rahman ◽

M. Elsafty ◽

A. Hattaba

Keyword(s):

Circular Dichroism ◽

Solid State ◽

Ir Spectra ◽

Chain Length ◽

Room Temperature ◽

Infrared Study ◽

Feature Characteristic ◽

C 50 ◽

The Stability ◽

Circular Dichroïsm

The conformation of elastin-like peptides Boc-Ala-Pro-Gly-Val-APEGM, Boc-Ala-Pro-Gly-Val-Gly-Val-APEGM, Boc-Ala-Pro-Gly-Val-Ala-Pro-Gly-Val-Gly-Val-APEGM, Boc-Ala-Pro-Gly-Val-Gly-Val-Ala-Pro-Gly-Val-Gly-Val-APEGM were examined in solution using circular dichroism at 30 °C, 50 °C, and 70 °C and in solid state by IR at room temperature. The studies show that the β-turn is a significant conformational feature for peptides under investigation in solution at 30 °C and 50 °C, but at 70 °C the tetra, hexa, and decapeptides show the CD feature characteristic of the β-structure while the dodecapeptide spectra show the presence of β-turn which indicates the stability of the β-turn at this chain length. The IR spectra show that in the solid state at room temperature all investigated peptides assume essentially a β-turn except the tetrapeptide which present evidence of antiparallel β-structure. The β-turn contribution in the IR spectra increases with the increase of the chain length of the peptide.

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Cholesterol in Serum and Lipoprotein Fractions

Clinical Chemistry ◽

10.1093/clinchem/2.3.145 ◽

1956 ◽

Vol 2 (3) ◽

pp. 145-159 ◽

Cited By ~ 187

Author(s):

Joseph T Anderson ◽

Ancel Keys

Keyword(s):

Human Serum ◽

Total Cholesterol ◽

Filter Paper ◽

Room Temperature ◽

Paper Electrophoresis ◽

Cholesterol Content ◽

Intraindividual Variability ◽

Detailed Data ◽

The Stability ◽

Source Of Error

Abstract 1. Methods are described for the separation, by paper electrophoresis and by cold ethanol, of α- and β-lipoproteins in 0.1 ml. of serum, with subsequent analysis of cholesterol in the separated portions. 2. It is shown that both methods of separation yield separated fractions containing substantially the same amounts of cholesterol. 3. Detailed data are given on the errors of measurement for total cholesterol and for cholesterol in the separated lipoprotein fractions. 4. Studies are reported on the stability of cholesterol in stored serum and on paper electrophoresis strips. It is shown that simple drying on filter paper causes no change in cholesterol content and yields a product that is stable for many weeks at ordinary room temperature. 5. The sources of variability in human serum cholesterol values are examined and it is shown that spontaneous intraindividual variability is a much greater source of error than the errors of measurement with these methods.

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Pressure dependent ultrasonic properties of hcp hafnium metal

Zeitschrift für Naturforschung A ◽

10.1515/zna-2021-0013 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Ramanshu P. Singh ◽

Shakti Yadav ◽

Giridhar Mishra ◽

Devraj Singh

Keyword(s):

Elastic Constants ◽

Pressure Range ◽

Room Temperature ◽

Ultrasonic Attenuation ◽

Coupling Constants ◽

Ultrasonic Properties ◽

Acoustic Coupling ◽

Third Order Elastic Constants ◽

The Stability ◽

The Given

Abstract The elastic and ultrasonic properties have been evaluated at room temperature between the pressure 0.6 and 10.4 GPa for hexagonal closed packed (hcp) hafnium (Hf) metal. The Lennard-Jones potential model has been used to compute the second and third order elastic constants for Hf. The elastic constants have been utilized to calculate the mechanical constants such as Young’s modulus, bulk modulus, shear modulus, Poisson’s ratio, and Zener anisotropy factor for finding the stability and durability of hcp hafnium metal within the chosen pressure range. The second order elastic constants were also used to compute the ultrasonic velocities along unique axis at different angles for the given pressure range. Further thermophysical properties such as specific heat per unit volume and energy density have been estimated at different pressures. Additionally, ultrasonic Grüneisen parameters and acoustic coupling constants have been found out at room temperature. Finally, the ultrasonic attenuation due to phonon–phonon interaction and thermoelastic mechanisms has been investigated for the chosen hafnium metal. The obtained results have been discussed in correlation with available findings for similar types of hcp metals.

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Non-adhesive lotus and other hydrophobic materials

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2007.2171 ◽

2008 ◽

Vol 366 (1870) ◽

pp. 1539-1556 ◽

Cited By ~ 116

Author(s):

David Quéré ◽

Mathilde Reyssat

Keyword(s):

Solid Surface ◽

Room Temperature ◽

Water Repellency ◽

Short Review ◽

Water Repellent ◽

Practical Applications ◽

Hydrophobic Materials ◽

Volatile Liquid ◽

Air Cushion ◽

The Stability

Superhydrophobic materials recently attracted a lot of attention, owing to the potential practical applications of such surfaces—they literally repel water, which hardly sticks to them, bounces off after an impact and slips on them. In this short review, we describe how water repellency arises from the presence of hydrophobic microstructures at the solid surface. A drop deposited on such a substrate can float above the textures, mimicking at room temperature what happens on very hot plates; then, a vapour layer comes between the solid and the volatile liquid, as described long ago by Leidenfrost. We present several examples of superhydrophobic materials (either natural or synthetic), and stress more particularly the stability of the air cushion—the liquid could also penetrate the textures, inducing a very different wetting state, much more sticky, due to the possibility of pinning on the numerous defects. This description allows us to discuss (in quite a preliminary way) the optimal design to be given to a solid surface to make it robustly water repellent.

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Longevity of Raw and Lyophilized Crude Urease Extracts

Sustainable Chemistry ◽

10.3390/suschem2020018 ◽

2021 ◽

Vol 2 (2) ◽

pp. 325-334

Author(s):

Neda Javadi ◽

Hamed Khodadadi Tirkolaei ◽

Nasser Hamdan ◽

Edward Kavazanjian

Keyword(s):

Crude Extract ◽

Room Temperature ◽

Low Cost ◽

Extraction Process ◽

Crude Extracts ◽

Simple Extraction ◽

Commercial Applications ◽

Stable Source ◽

The Stability ◽

The Cost

The stability (longevity of activity) of three crude urease extracts was evaluated in a laboratory study as part of an effort to reduce the cost of urease for applications that do not require high purity enzyme. A low-cost, stable source of urease will greatly facilitate engineering applications of urease such as biocementation of soil. Inexpensive crude extracts of urease have been shown to be effective at hydrolyzing urea for carbonate precipitation. However, some studies have suggested that the activity of a crude extract may decrease with time, limiting the potential for its mass production for commercial applications. The stability of crude urease extracts shown to be effective for biocementation was studied. The crude extracts were obtained from jack beans via a simple extraction process, stored at room temperature and at 4 ℃, and periodically tested to evaluate their stability. To facilitate storage and transportation of the extracted enzyme, the longevity of the enzyme following freeze drying (lyophilization) to reduce the crude extract to a powder and subsequent re-hydration into an aqueous solution was evaluated. In an attempt to improve the shelf life of the lyophilized extract, dextran and sucrose were added during lyophilization. The stability of purified commercial urease following rehydration was also investigated. Results of the laboratory tests showed that the lyophilized crude extract maintained its activity during storage more effectively than either the crude extract solution or the rehydrated commercial urease. While incorporating 2% dextran (w/v) prior to lyophilization of the crude extract increased the overall enzymatic activity, it did not enhance the stability of the urease during storage.

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Facile Organometallic Synthesis of Fe-Based Nanomaterials by Hot Injection Reaction

Nanomaterials ◽

10.3390/nano11051141 ◽

2021 ◽

Vol 11 (5) ◽

pp. 1141

Author(s):

Georgia Basina ◽

Hafsa Khurshid ◽

Nikolaos Tzitzios ◽

George Hadjipanayis ◽

Vasileios Tzitzios

Keyword(s):

Room Temperature ◽

Colloidal Particles ◽

Iron Pentacarbonyl ◽

Vibrating Sample Magnetometer ◽

X Ray Diffraction ◽

Organometallic Synthesis ◽

X Ray ◽

Transmission Electron ◽

Hot Injection ◽

The Stability

Fe-based colloids with a core/shell structure consisting of metallic iron and iron oxide were synthesized by a facile hot injection reaction of iron pentacarbonyl in a multi-surfactant mixture. The size of the colloidal particles was affected by the reaction temperature and the results demonstrated that their stability against complete oxidation related to their size. The crystal structure and the morphology were identified by powder X-ray diffraction and transmission electron microscopy, while the magnetic properties were studied at room temperature with a vibrating sample magnetometer. The injection temperature plays a very crucial role and higher temperatures enhance the stability and the resistance against oxidation. For the case of injection at 315 °C, the nanoparticles had around a 10 nm mean diameter and revealed 132 emu/g. Remarkably, a stable dispersion was created due to the colloids’ surface functionalization in a nonpolar solvent.

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The Formation of Chitosan-Coated Rhamnolipid Liposomes Containing Curcumin: Stability and In Vitro Digestion

Molecules ◽

10.3390/molecules26030560 ◽

2021 ◽

Vol 26 (3) ◽

pp. 560

Author(s):

Wei Zhou ◽

Ce Cheng ◽

Li Ma ◽

Liqiang Zou ◽

Wei Liu ◽

...

Keyword(s):

Room Temperature ◽

Functional Foods ◽

Positive Charge ◽

Physical Stability ◽

In Vitro Digestion ◽

Salt Addition ◽

High Transformation ◽

Liposomal Delivery ◽

The Stability

There is growing interest in developing biomaterial-coated liposome delivery systems to improve the stability and bioavailability of curcumin, which is a hydrophobic nutraceutical claimed to have several health benefits. The curcumin-loaded rhamnolipid liposomes (Cur-RL-Lips) were fabricated from rhamnolipid and phospholipids, and then chitosan (CS) covered the surface of Cur-RL-Lips by electrostatic interaction to form CS-coated Cur-RL-Lips. The influence of CS concentration on the physical stability and digestion of the liposomes was investigated. The CS-coated Cur-RL-Lips with RL:CS = 1:1 have a relatively small size (412.9 nm) and positive charge (19.7 mV). The CS-coated Cur-RL-Lips remained stable from pH 2 to 5 at room temperature and can effectively slow the degradation of curcumin at 80 °C; however, they were highly unstable to salt addition. In addition, compared with Cur-RL-Lips, the bioavailability of curcumin in CS-coated Cur-RL-Lips was relatively high due to its high transformation in gastrointestinal tract. These results may facilitate the design of a more efficacious liposomal delivery system that enhances the stability and bioavailability of curcumin in nutraceutical-loaded functional foods and beverages.

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Stability of dronabinol capsules when stored frozen, refrigerated, or at room temperature

American Journal of Health-System Pharmacy ◽

10.2146/ajhp150501 ◽

2016 ◽

Vol 73 (14) ◽

pp. 1088-1092 ◽

Cited By ~ 3

Author(s):

Michael F. Wempe ◽

Alan Oldland ◽

Nancy Stolpman ◽

Tyree H. Kiser

Keyword(s):

High Performance ◽

Room Temperature ◽

Oxidative Degradation ◽

Storage Condition ◽

Sesame Oil ◽

Forced Degradation ◽

Product Packaging ◽

Time Points ◽

The Stability ◽

Minimal Reduction

Abstract Purpose Results of a study to determine the 90-day stability of dronabinol capsules stored under various temperature conditions are reported. Methods High-performance liquid chromatography (HPLC) with ultraviolet (UV) detection was used to assess the stability of dronabinol capsules (synthetic delta-9-tetrahydrocannabinol [Δ9-THC] mixed with high-grade sesame oil and other inactive ingredients and encapsulated as soft gelatin capsules) that were frozen, refrigerated, or kept at room temperature for three months. The dronabinol capsules remained in the original foil-sealed blister packs until preparation for HPLC–UV assessment. The primary endpoint was the percentage of the initial Δ9-THC concentration remaining at multiple designated time points. The secondary aim was to perform forced-degradation studies under acidic conditions to demonstrate that the HPLC–UV method used was stability indicating. Results The appearance of the dronabinol capsules remained unaltered during frozen, cold, or room-temperature storage. Regardless of storage condition, the percentage of the initial Δ9-THC content remaining was greater than 97% for all evaluated samples at all time points over the three-month study. These experimental data indicate that the product packaging and the sesame oil used to formulate dronabinol capsules efficiently protect Δ9-THC from oxidative degradation to cannabinol; this suggests that pharmacies can store dronabinol capsules in nonrefrigerated automated dispensing systems, with a capsule expiration date of 90 days after removal from the refrigerator. Conclusion Dronabinol capsules may be stored at room temperature in their original packaging for up to three months without compromising capsule appearance and with minimal reduction in Δ9-THC concentration.

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