含磷抗原及含硫抗原诱导的抗体水解活性的比较

以过渡态理论为基础,以羧肽酶A(CPA)的天然肽底物马脲酰-苯丙氨酸为模型,分别以磷原子和硫原子为四面体过渡态类似物的中心原子来设计和合成了半抗原和全抗原,将两类抗原用免疫方法诱导制备出抗体,然后对两类抗体水解肽键的活性进行比较。     

膦、胂叶立德的化学与应用(ⅩⅣ)——膦、胂叶立德和丙炔酸甲酯的反应及部分加合物的水解

本文研究了甲氧羰基亚甲基三苯基胂(1b)、苯甲酰基亚甲基三苯基膦(1b)、胂、乙酰基亚甲基三苯基膦、胂、氰基亚甲基三苯基膦、胂、对-硝基苯基亚甲基三苯基膦(1i)和1-甲基-2-乙氧羰基亚甲基三苯基膦等9个膦、胂叶立德与丙炔酸甲酯(2)的反应以及1b和2反应的加合产物1,3-二甲氧羰基亚烯丙基三苯基胂(3b)及1i和2反应的加合产物1-甲氧羰基-3-对硝基苯基亚烯丙基三苯基膦(3i)在含水甲醇中的水解。     

2-,3-和4-溴甲基吡啶的水解反应的动力学研究

用HPLC测定了2-、3-和4-溴甲基吡啶在60℃、离子强度μ为0.15、pH 0.9～9.9的缓冲溶液中水解成相应的羟甲基吡啶的反应速度.通过数学处理,求得溴甲基吡啶的一级和二级反应速度常数以及溴甲基吡啶共轭酸的一级反应速度常数.水解反应的可能机理是S_N1和S_N2.     

Synthese,Struktur und Hydrolyse von Tetrakis(tetrahydropyran)strontium-bis[bis(dimethylisopropylsilyl)phosphanid]

Synthesis, Structures, and Hydrolysis of Tetrakis(tetrahydropyran)strontium Bis[bis(dimethylisopropylsilyl)phosphanide] The metalation of bis(dimethylisopropylsilyl)phosphane in tetrahydropyran with strontium bis[bis(trimethylsilyl)amide] yields almost quantitatively tetrakis(tetrahydropyran)strontium bis[bis(dimethylisopropylsilyl)phosphanide], which crystallizes in the monoclinic space group C2/c (a = 2340.71(1), b = 1028.74(1), c = 2186.02(1) pm, β = 91.03(1)°, Z = 4, wR₂ = 0.0759). The phosphanide ligands are in trans-positions and the P–Sr–P bond angle is found to be 168.5°. Partial hydrolysis of this compound leads to the formation of bis(dimethylsilylisopropylsilyl)phosphane and Sr₄O[P(SiMePr)₂]₆ with a central oxygen atom surrounded tetrahedrally by four alkaline earth metal atoms (monoclinic, space group C2/c, C2/c, a = 2265.83(6), b = 1702.11(5), c = 2462.46(9) pm, β = 91.34(1)°, Z = 4, wR₂ = 0.1057). The edges of the strontium tetrahedron are bridged by phosphanide ligands. The metal atoms are coordinated trigonal planarily by three phosphanide groups.     

3. Acetate manufacturing,process and technology 3.1 Chemistry of cellulose acetylation

Nowadays Celluloseacetate is mainly produced with the acetic acid process. After an activation with acetic acid and sulfuric acid the acetylation of the cellulose starts by adding acetic anhydride. The temperature and the catalyst concentration play an important role for the reaction. Beneath acetylation also degradation of the cellulose chains occurs. In the first step of the process cellulosetriacetate is formed. In a second step, the hydrolysis, several acetyl groups are removed to achieve an average degree of substitution of 2,5. The water content in this step influences the acetyl distribution.     

Modulating Electronic Metal-Support Interactions to Boost Visible-Light-Driven Hydrolysis of Ammonia Borane: Nickel-Platinum Nanoparticles Supported on Phosphorus-Doped Titania

Ammonia borane (AB) is a promising material for chemical H₂ storage owing to its high H₂ density (up to 19.6 wt %). However, the development of an efficient catalyst for driving H₂ evolution through AB hydrolysis remains challenging. Therefore, a visible-light-driven strategy for generating H₂ through AB hydrolysis was implemented in this study using Ni−Pt nanoparticles supported on phosphorus-doped TiO₂ (Ni-Pt/P-TiO₂) as photocatalysts. Through surface engineering, P-TiO₂ was prepared by phytic-acid-assisted phosphorization and then employed as an ideal support for immobilizing Ni−Pt nanoparticles via a facile co-reduction strategy. Under visible-light irradiation at 283 K, Ni₄₀Pt₆₀/P-TiO₂ exhibited improved recyclability and a high turnover frequency of 967.8 mol mol_Pt⁻¹ min⁻¹. Characterization experiments and density functional theory calculations indicated that the enhanced performance of Ni₄₀Pt₆₀/P-TiO₂ originated from a combination of the Ni−Pt alloying effect, the Mott–Schottky junction at the metal-semiconductor interface, and strong metal-support interactions. These findings not only underscore the benefits of utilizing multipronged effects to construct highly active AB-hydrolyzing catalysts, but also pave a path toward designing high-performance catalysts by surface engineering to modulate the electronic metal-support interactions for other visible-light-induced reactions.     

CuCoO2 Nanoparticles as a Nanoprotease for Selective Proteolysis with High Efficiency at Room Temperature

Many nanoproteases contain tetravalent metal ions and catalyze peptide-bond hydrolysis only at high temperature (60 °C). Here, we report a new and effective strategy to explore nanoproteases from nanoparticles containing low valent metal ions. We found that flower-like CuCoO₂ nanoparticles (CuCoO₂ NPs) containing low valent Cu⁺ possessed excellent catalytic activity towards selective cleavage of peptide bonds with hydrophobic residues in bovine serum albumin (BSA) at room temperature. CuCoO₂ NPs exhibited excellent stability and had great reusability. CuCoO₂ NPs also hydrolyzed heat-denatured and surfactant-denatured BSA. Mechanism analysis revealed that the high Lewis acidity of Co³⁺ and the low valence of Cu⁺ were both essential for the high protease activity of CuCoO₂ NPs. The flower-like structure of CuCoO₂ NPs and the strong nucleophilicity of Cu⁺-bound hydroxyl endow them with excellent catalytic performance. The findings open a new way for the design and discovery of high-efficiency nanoproteases.