Spin Labeled Bovine Serum Albumin, Spin Labeled Bovine Serum Albumin Chelating Agents and Their Gadolinium Complexes. Potential Contrast Enhancing Agents for Magnetic Resonance Imaging
作者:George Sosnovsky、N. Uma Maheswara Rao、J. Lukszo、Robert C. Brasch
DOI:10.1515/znb-1986-0917
日期:1986.9.1
(BSA) was spinlabeled using the active esters 3 and 5 containing a nitroxyl radical to give the spinlabeled BSA derivatives 4 and 6. Spinlabeled C D TA , DTPA and TTHA chelating agents 10, 13 and 16 and the corresponding BSA derivatives 17, 18 and 19 and their gadolinium complexes 20, 21 and 22 were synthesized. All these BSA derivatives were evaluated as possible contrastenhancingagents for NMR
Certain maleimide-N-alkylenecarboxylate-ortho-nitrobenzenesulfonic acid
申请人:Cetus Corporation
公开号:US04954637A1
公开(公告)日:1990-09-04
Coupling of biological materials is disclosed via 4-hydroxy-3-nitrobenzene sulfonic acid sodium salt (HNSA) esters. The novel activated esters are structured so as to react at one end with an amine group of a selected biological or non-biological material, thereby releasing the spectroscopically monitorable HNSA dianion, and at the other end with, typically, a sulfhydryl group of a second material which may or may not be biological. The esters provide for a cross-linking reaction that may be easily controlled and monitored.
Coupling of biological materials is disclosed via 4-hydroxy-3-nitrobenzene sulfonic acid sodium salt (HNSA) esters. The novel activated esters are structured so as to react at one end with an amine group of a selected biological or non-biological material, thereby releasing the spectroscopically monitorable HNSA dianion, and at the other end with, typically, a sulfhydryl group of a second material which may or may not be biological. The esters provide for a cross-linking reaction that may be easily controlled and monitored.
Kinetics and Mechanism of Aminolysis of Phenyl Acetates in Aqueous Solutions of Poly(ethylenimine)
作者:Antonio Arcelli、Carlo Concilio
DOI:10.1021/jo9514681
日期:1996.1.1
Second-order rate constants (k(n)) for the aminolysis of some phenyl acetates with poly(ethylenimine) (PEI) were obtained in a pH range 4.36-11.20 at 25 degrees C in 1 M KCl. Linear Bronsted-type plots (log k(n) vs pK(N) of PEI) were found for less reactive esters 2-nitrophenyl acetate, 4-acetoxy-3-chlorobenzoic acid, and 4-acetoxybenzenesulfonate with slopes of 0.92, 0.99, and 0.82, respectively.
在pH范围4.36-11.20、25摄氏度,1 M KCl中,获得了一些乙酸苯酯与聚乙烯亚胺(PEI)进行氨解的二级速率常数(k(n))。发现具有较低反应性的酯2-硝基苯乙酸酯,4-乙酰氧基-3-氯苯甲酸和4-乙酰氧基苯磺酸酯的线性布朗斯台德图(PEI的log k(n)vs pK(N))的斜率分别为0.92、0.99,和0.82分别。获得3-乙酰氧基-2,6-二硝基苯甲酸和4-乙酰氧基-3-硝基苯磺酸的曲线图,其与逐步反应一致。最可能的机制涉及四面体中间体(T(+/-))的存在以及当多胺的碱度增加时从其分解到形成的速率决定步骤的变化。使用半经验方程式来计算曲线图的极限斜率值(0。曲线的曲率中心分别为9和0.1(酯类)和pK(N)(pK(N度)分别为7.94和9.02)。pK(N度)的值低于使用单单体胺对相同酯进行氨解的估计值(pK(n度)> 11),因为氨基时四面体的芳基氧化物离子具有更好