What are the properties and applications of 12-crown-4? Introduction 12-Crown-4, also known as 1,4,7,10-tetraoxacyclododecane, is a high-molecular-weight chemical raw material with a unique molecular structure. Its molecular formula is C?H??O?, consisting of a large ring structure composed of twelve atoms, including four oxygen atoms and eight carbon atoms. This unique structure gives 12-crown-4 distinctive physical and chemical properties, making it widely used in the fields of chemistry and materials science. It exhibits good stability at room temperature and pressure, but may react dangerously when in contact with oxidizing substances. Therefore, special attention should be paid to avoiding contact with oxidizing substances during storage and use. Properties of 12-crown-4 Preparation Methods The preparation of 12-crown-4 mainly relies on organic synthesis techniques. One common method involves constructing its macrocyclic structure through cyclization reactions. The specific steps include selecting appropriate precursor compounds, converting them into intermediate compounds with a macrocyclic structure through a series of chemical reactions, and finally obtaining the target product 12-crown-4 through further modification and purification. It is essential to strictly control reaction conditions and reaction time during the preparation process to ensure the purity and quality of the product. Additionally, attention should be paid to the by-products and impurities that may be generated during the reaction, and corresponding measures should be taken for separation and removal. Applications Complexing agents and phase transfer agents: 12-crown-4 can form stable complexes with metal ions, making it suitable for use as a complexing agent. Additionally, due to its unique molecular structure, it can also serve as a phase transfer agent, facilitating chemical reactions between different phases. Metal ion recognition: 12-crown-4 can be used as a recognition molecule in chemical sensors to detect the presence and concentration of specific metal ions. This recognition ability holds potential application value in environmental monitoring, biomedical, and other fields. Coordination chemistry: In coordination chemistry, 12-crown-4 can act as a ligand, forming stable complexes with metal ions. These complexes have significant application value in the separation, extraction, and detection of metal ions. References [1] Elvidge B R, Arndt S, Zeimentz P M, et al. Cationic Rare-Earth Metal Trimethylsilylmethyl Complexes Supported by THF and 12-Crown-4 Ligands: Synthesis and Structural Characterization. Inorganic Chemistry, 2005, 44(19): 6777-6788. [2] Rogers R D, Bond A H. Crown ether complexes of lead(II) nitrate. Crystal structures of the 12-crown-4, 15-crown-5, benzo-15-crown-5 and 18-crown-6 complexes. Inorganica Chimica Acta, 1992, 192(2): 163-171. [3] Takeda, Yasuyuki. The solvent extraction of alkali metal picrates by 12-crown-4. Bulletin of the Chemical Society of Japan, 1980, 53(8): 2393-2394. [4] Ma?gorzata Jó?wiak. The effect of properties of water–organic solvent mixtures on the solvation enthalpy of 12-crown-4, 15-crown-5, 18-crown-6 and benzo-15-crown-5 ethers at 298.15 K. Thermochimica Acta, 2004, 417(1): 31-41. 查看更多
Recombinant Rat Uteroglobin: What are its structural characteristics and biological activities? Introduction [1] Several decades ago, researchers Joseph Daniel Jr. from the United States and Henning Beier from Germany independently discovered and reported a new protein called blastokinin, induced by steroid hormones in the uterus of pregnant rabbits. This protein was later named Uteroglobin (UG). UG was found to be widely distributed, not only expressed in the uterus but also detected in the thyroid, respiratory tract, digestive tract, pancreas, prostate, mammary glands, pituitary gland, testes, as well as peripheral blood and urine. In previous studies, UG was also referred to as progesterone-binding protein. The conservation of Recombinant Rat Uteroglobin across species, including mice, rats, hamsters, rabbits, pigs, and humans, suggests its important physiological function. However, its exact physiological function remains unclear. Therefore, extensive in vitro and in vivo experiments have been conducted, including the generation of transgenic mice, to study the structure and function of UG. Surprisingly, although Recombinant Rat Uteroglobin is not expressed in the kidneys, mice with UG gene knockout exhibit significant renal damage, particularly resembling the clinical and pathological features of IgA nephropathy. Thus, Recombinant Rat Uteroglobin has become a new breakthrough in the study of the pathogenesis of kidney diseases. Structural Characteristics of Recombinant Rat Uteroglobin [2] X-ray diffraction techniques have revealed that Recombinant Rat Uteroglobin is a homodimeric protein consisting of two subunits linked by two disulfide bonds. One disulfide bond is between Cys-3 and Cys-69', and the other is between Cys-3' and Cys-69. The two subunits adopt a reverse equilibrium structure in space. Each subunit consists of 70 amino acids and contains four α-helices with a bend between α-helix 2 and α-helix 3. The dimer forms three cavities in its spatial conformation: C1, C2, and C3. C1 exists between the two subunits and is composed of hydrophobic amino acid residues except for Tyr-21 and Tyr-21'. C2 and C3 are located inside each subunit and are composed of α-helix 1, α-helix 2, and α-helix 3, which contain a large number of hydrophobic amino acids. The structural characteristics of Recombinant Rat Uteroglobin are highly similar among different species. Biological Activities of Recombinant Rat Uteroglobin [3] Initially, it was found that Recombinant Rat Uteroglobin binds to progesterone, polychlorinated biphenyls, and retinol. However, the significance of these bindings remains unclear. Recombinant Rat Uteroglobin may serve as a carrier for certain steroid hormones to reduce their toxic effects on early embryonic development. UG is considered to be a mediator of the immunosuppressive effects associated with progesterone during conception, making it a "natural immunosuppressant." Further research has demonstrated that Recombinant Rat Uteroglobin can protect embryos from maternal immune attacks, suggesting its immunoregulatory role. This immunoregulatory effect can be amplified by transaminases, and it has been found that UG is a substrate for transaminases in related experiments. Recombinant Rat Uteroglobin is primarily expressed in bronchial epithelium, which is exposed to a large number of environmental antigens. This indicates that Recombinant Rat Uteroglobin is a non-specific regulator of immune activity. References [1] Zhang Z, Kundu GC, Yuan CJ, et al. Science, 1997;276:1408-1412 [2] Mukherjee AB, Kundu GC, Mantile-Selvaggi G, et al. Cell Mol Life Sci, 1999;55:771-87 [3] Manjunath R, Chung SI, Mukherjee AB. Biochem Biophys Res Commun, 1984;121:400-407 查看更多
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