Palladium‐Mediated Cleavage of Proteins with Thiazolidine‐Modified Backbone in Live Cells

Chemical protein synthesis and biorthogonal modification chemistries allow production of unique proteins for a range of biological studies. Bond‐forming reactions for site‐selective protein labeling are commonly used in these endeavors. Selective bond‐cleavage reactions, however, are much less explored and still pose a great challenge. In addition, most of studies with modified proteins prepared by either total synthesis or semisynthesis have been applied mainly for in vitro experiments with very limited extension to live cells. Reported here is an approach for studying uniquely modified proteins containing a traceless cell delivery unit and palladium‐based cleavable element for chemical activation, and monitoring the effect of these proteins in live cells. This approach is demonstrated for the synthesis of a caged ubiquitin‐aldehyde, which was decaged for the inhibition of deubiquitinases in live cells.     

胆红素的间接分光光度分析研究

胆红素在浓Ｈ２ＳＯ４与冰醋酸的混合酸介质中，可被Ｈ２Ｏ２氧化为稳定的绿色产物，该溶液稀释后变成深蓝色，在５９０ｎｍ波长处有最大吸收，其吸收值与胆红素浓度在１×１０－６～２×１０－５ｍｏｌ／Ｌ范围内成线性关系。可用于间接测定感冒通片中胆红素的含量。     

胆红素的间接极谱测定

在Hg~(2+)(或Hg~+)-EDTA-磷酸钠缓冲溶液中,胆红素可被迅速氧化成浅绿色产物。该产物可在-0.83V(vs.SCE)左右产生一灵敏的极谱波,其导数波高与胆红素浓度在4×10~(-7)～6×10~(-6)mol/L范围内呈线性关系,因此该波可用于胆红素的间接测试。本文对胆红素的氧化机制和极谱波的性质进行了研究。发现胆红素被氧化成了胆绿素,而所产生的极谱波为一催化波。     

胆红素的间接光度测定

本文研究了在ｐＨ１０的氨－氯化铵溶液中铜对胆红素的催化氧化作用及其氧化产物胆绿素与铜形成络合物的性质。该络合物在３４０ｎｍ波长处有最大吸收，可用于对胆红素的间接光度测定。其线性范围为１．２×１０＾－６～３．０×１０＾－５ｍｏｌ／Ｌ。     

Transient Incomplete Separation Facilitates Finding Accurate Equilibrium Dissociation Constant of Protein–Small Molecule Complex

Current practical methods for finding the equilibrium dissociation constant, K_d, of protein–small molecule complexes have inherent sources of inaccuracy. Introduced here is “accurate constant via transient incomplete separation” (ACTIS), which appears to be free of inherent sources of inaccuracy. Conceptually, a short plug of the pre‐equilibrated protein–small molecule mixture is pressure‐propagated in a capillary, causing fast transient incomplete separation of the complex from the unbound small molecule. A superposition of signals from these two components is measured near the capillary exit and used to calculate a fraction of unbound small molecule, which, in turn, is used to calculate K_d. Herein the validity of ACTIS is proven theoretically, its accuracy is verified by computer simulation, and its practical use is demonstrated. ACTIS has the potential to become a reference‐standard method for determining K_d values of protein–small molecule complexes.     

血液灌流治疗高胆红素血症的研究进展

胆红素是血红素的分解产物，由于它的毒性，去除胆红素一直是人工肝支持装置研究的热门课题，本文综述了包括ＮＫ－１１０，ＢＲ－６０１，ＡＲ－１，ＭＲ等在内的十几种用于治疗高胆红素血症的高效吸附剂。     

胆红素单二元醇酯的合成及其在溶液中的结构

利用二元醇的单甲苯磺酸酯同胆红素的四丁基氢氧化铵盐反应，合成出胆红素单葡萄醛酸酯的模型化合物－２个胆红素单乙二醇酯和２个胆红素单丙二醇酯，通过＾１Ｈ ＮＭＲ对它们在溶液中的结构进行了研究。     

Derivative Spectrophotometry: Determination of Bilirubin in Amniotic Fluid

Abstract

Spectrophotometric analysis presents very often the disadvantage of interferences by substances which can absorb near the substance of interest. The use of derivative spectra allows to overcome this difficulty. In this paper we describe a method for determination of bilirubin in amniotic fluid based on use of derivative spectrophotometry. This method presents some advantages of accuracy and quickness in comparison with the ones normally used.     

胆红素定量分析的研究进展

在临床应用和实验研究中,胆红素的定量分析方法已经取得了长足的发展,有多种方法可以定量分析胆红素的浓度。本文对胆红素定量分析方法及理论依据作一综述。     

On the Conformation of Bilirubin Ditaurate

Summary.  The first optically active taurine conjugate of a bilirubin was prepared by reaction of taurine sodium salt with the mixed anhydride formed from reaction of (βS,β′S)-dimethylmesobilirubin-XIIIα with isobutyl chloroformate. Analysis of the circular dichroism spectra of the conjugate in water and chloroform indicate a conformational preference for the (M)-helical ridge-tile conformation, thus providing the first spectroscopic evidence on the conformation of ditaurobilirubins. Corresponding author. E-mail: lightner@scs.unr.edu Received July 5, 2002; accepted July 15, 2002     

新型交联甲壳糖吸附树脂对胆红素的吸附性能研究

以天然甲壳素为原料合成了珠状高分子吸附剂，研究了吸附剂在磷酸二氢钠和磷酸氢二钠缓冲溶液中对非结合型胆红素的吸附性能，实验结果表明：交联甲壳糖吸附树脂对非结合型胆红素很好的吸附效果。     

胆红素和胆绿素的电化学行为初探

本文用电化学方法和光谱方法对胆红素和胆绿素在磷酸钠溶液（ｐＨ１１．５）中的电化学行为进行了研究。发现胆红素在磷酸钠溶液中可在－０．２５Ｖ、－１．３２Ｖ和－１．４７Ｖ（ｖｓ．ＳＣＥ）左右产生三个阴极化波，在－０．２５Ｖ左右产生一阳极化波，其中－０．２５Ｖ左右处的一对波被证实为可逆波，由胆红素与汞（Ⅱ）配合物的氧化还原引起，而另外二波均为不可逆波，由胆红素内吡咯环的氧化还原产生。胆绿素可在－０．３４Ｖ和０．９８Ｖ左右产生极谱波，－０．３４Ｖ处波为胆绿素与汞（Ⅲ）配合物的氧化还原所致，－０．９８Ｖ处波为一催化波。胆红素和胆绿素产生的这些波均具有吸附波特性，可用于它们的分析测试。