Were Ancestral Proteins Less Specific?

Some have hypothesized that ancestral proteins were, on average, less specific than their descendants. If true, this would provide a universal axis along which to organize protein evolution and suggests that reconstructed ancestral proteins may be uniquely powerful tools for protein engineering. Ancestral sequence reconstruction studies are one line of evidence used to support this hypothesis. Previously, we performed such a study, investigating the evolution of peptide-binding specificity for the paralogs S100A5 and S100A6. The modern proteins appeared more specific than their last common ancestor (ancA5/A6), as each paralog bound a subset of the peptides bound by ancA5/A6. In this study, we revisit this transition, using quantitative phage display to measure the interactions of 30,533 random peptides with human S100A5, S100A6, and ancA5/A6. This unbiased screen reveals a different picture. While S100A5 and S100A6 do indeed bind to a subset of the peptides recognized by ancA5/A6, they also acquired new peptide partners outside of the set recognized by ancA5/A6. Our previous work showed that ancA5/A6 had lower specificity than its descendants when measured against biological targets; our new work shows that ancA5/A6 has similar specificity to the modern proteins when measured against a random set of peptide targets. This demonstrates that altered biological specificity does not necessarily indicate altered intrinsic specificity, and sounds a cautionary note for using ancestral reconstruction studies with biological targets as a means to infer global evolutionary trends in specificity.     

Information and Communication Technology‐Enabled Low Carbon Technologies

This article outlines the subsector of the information and communication technology (ICT) industry concerned with reducing the economy's environmental impact, dubbed ICT‐enabled low carbon technologies (ICTeLCTs). The article is based on a study funded by United Kingdom (UK) Trade and Investment, a division of the UK Department for Business, Innovation and Skills. ICTeLCTs can be segmented into specialist and generalist operators. Specialists focus on one or two ICT applications to monitor or reduce environmental issues, while generalists supply products and services enabling a firm or a private household to reduce the environmental impact of its activities. The subsector can be further segmented into green ICT, energy management, building management, carbon accounting, waste management, intelligent transport systems (ITSs), and water management. The main factors driving ICTeLCTs include legislation, voluntary environmental standards, corporate social responsibility (CSR) activities, customer demand, and competitive market factors. Policy makers should continue to drive the growth of ICTeLCTs with the introduction and refinement of environmental legislation regulating energy use and markets.     

Prize Crossword

This article describes four rapid tests for the viability of stored seeds. Since each test is easily applied, and does not require any apparatus other than a conductance bridge and a conductivity cell, it is suggested that the tests could be employed as a basis for class experiments, individual projects at sixth-form level, or for more advanced research work. Typical results are given and some possible applications of the tests are discussed.     

Application of partial restriction procedure in both shotgun and non-random strategies for nucleotide sequencing

Partial digestion of a target DNA fragment with 4-bp-recognition restriction enzymes followed by a forced ligation to an M13 vector was employed for the construction of a subfragment library. The library can be used for either shotgun or non-random nucleotide sequencing. Application of the partial digests generated with the 4-bp recognition restriction enzymes instead of DNase I in the improved non-random strategy for nucleotide sequencing (Li and Wu, 1987) made the procedure as easy as that of the random strategy. The library can also be used in shotgun nucleotide sequencing directly, and few self-ligated subfragments were found. The usefulness of this procedure was demonstrated by the sequencing of a goat 6.5-kb EcoRI fragment, which is located 5' to the globin gene.     

Improving the pharmacokinetic properties of biologics by fusion to an anti-HSA shark VNAR domain

Advances in recombinant antibody technology and protein engineering have provided the opportunity to reduce antibodies to their smallest binding domain components and have concomitantly driven the requirement for devising strategies to increase serum half-life to optimise drug exposure, thereby increasing therapeutic efficacy. In this study, we adopted an immunization route to raise picomolar affinity shark immunoglobulin new antigen receptors (IgNARs) to target human serum albumin (HSA). From our model shark species, Squalus acanthias, a phage display library encompassing the variable binding domain of IgNAR (VNAR) was constructed, screened against target, and positive clones were characterized for affinity and specificity. N-terminal and C-terminal molecular fusions of our lead hit in complex with a naïve VNAR domain were expressed, purified and exhibited the retention of high affinity binding to HSA, but also cross-selectivity to mouse, rat and monkey serum albumin both in vitro and in vivo. Furthermore, the naïve VNAR had enhanced pharmacokinetic (PK) characteristics in both N- and C-terminal orientations and when tested as a three domain construct with naïve VNAR flanking the HSA binding domain at both the N and C termini. Molecules derived from this platform technology also demonstrated the potential for clinical utility by being available via the subcutaneous route of delivery. This study thus demonstrates the first in vivo functional efficacy of a VNAR binding domain with the ability to enhance PK properties and support delivery of multifunctional therapies.     

以重组TACE胞外功能域从噬菌体随机肽库中筛选TACE的抑制肽

肿瘤坏死因子转换酶 (TACE)是加工裂解TNF-α前体的关键酶 ,参与了许多炎症的发生发展过程。为通过肽库筛选得到TACE的抑制肽 ,首先制备筛选靶分子 ,用RT PCR从人外周血单核细胞中分别扩增出TACE的催化区 (T800 )和整个胞外区 (T1300 ) ,然后分别克隆至pET-28a和pET-28c中 ,转化大肠杆菌BL2-1(DE3) ,经IPTG诱导表达出带有His-tag的目的蛋白 ,两者均为包涵体 ,变性复性后过Ni²⁺-NTA亲和层析柱得到纯度达90%的重组蛋白。以纯化的重组T800和T1300分别筛选噬菌体展示随机 15肽库 ,对筛选克隆进行ELISA检测、竞争抑制实验和序列分析。从两个独立的筛选过程中得到一个相同的阳性克隆序列“TRWLVYFSRPYLVAT” ,固相Fmoc法合成该短肽 ,观察其在LPS诱导人单核细胞产生sTNF-α中的作用。结果表明 ,筛选到的短肽可显著抑制TACE的活性 ,减少TNF-α的分泌 ,抑制率可达 60.3% ,为抗炎小分子药物的设计和改造提供线索和依据。     

分枝杆菌噬菌体生物学特性探讨

为了确定不同分枝杆菌噬菌体的宿主菌以及扩增方法和最佳保存方法,观察了七种分枝杆菌噬菌体对结核分枝杆菌、耻垢分枝杆菌的裂解情况,并分别于感染后 24、48小时采用离心 过滤、孵育 过滤方法收集噬菌体比较扩增效率,采用不同稳定剂对分枝杆菌噬菌体进行液体和冻干保存,在不同时间段采用琼脂双层法检测其效价。结果显示:①D29分枝杆菌噬菌体能同时较高效地裂解结核分枝杆菌和耻垢分枝杆菌;②感染 48小时后采用孵育 过滤方法收集的噬菌体效价高,方法简单;③液体 4℃保存的噬菌体稳定性好, 70℃液体保存和冻干后 4℃、室温、37℃保存依据不同稳定剂而相差较大。因此,在 48小时后采用孵育 过滤方法收集噬菌体具有高效率特性并且简单易行,噬菌体液体 4℃保存简单、有效,值得推荐。     

一种新的乙型肝炎病毒表面抗原结合蛋白的筛选、表达及其生物学活性的初步研究

为了研究乙肝病毒侵染肝细胞过程中的功能蛋白 ,通过印迹免疫分析技术从人肝cDNA噬菌体表达库中筛选出一株编码乙肝表面抗原结合蛋白 (hepatitisBsurfaceantigenbindingprotein ,HBsAg BP)的cDNA克隆 .基因测序结果表明 ,该cDNA具有独立的开放阅读框架 ,编码 1个由 344个氨基酸残基构成的可溶性蛋白分子 ,属于免疫球蛋白超家族成员 .将该基因克隆到原核表达载体pTriplEx后 ,在E .coliXL1 Blue菌株中获得 4 4kD的重组蛋白 .重组蛋白经Western印迹和ELISA实验证明具有与乙肝表面抗原特异性结合的能力 .进一步经流式细胞仪实验显示 ,在纯化的重组蛋白存在的情况下 ,天然的HBsAg与肝细胞株HepG2的亲和力显著增高 .结果显示 ,该乙肝表面抗原结合蛋白可能是介导乙肝病毒对肝细胞亲和侵染的可溶性辅助受体 .     

Innovation and technological knowledge in the Upper Paleolithic of Northern Eurasia

The technology of modern humans is unique in the animal kingdom with respect to its complexity and capacity for innovation. Evidence of technological complexity and creativity in the archeological record is broadly coincident with and presumably related to traces of creativity in art, music, ritual, and other forms of symbolism. The pattern of modern human technology is part of a larger package of behavior (sometimes referred to as “behavioral modernity”) that emerges with the appearance of industries in Eurasia classified as Upper Paleolithic, but has deeper roots in the African Middle Stone Age. 1 - 5 .     

应用体内诱导抗原技术筛选结核分枝杆菌体内表达基因

为寻找新型抗结核药物靶标 ,采用体内诱导抗原技术筛选结核分枝杆菌的体内诱导基因。首先构建了结核分枝杆菌基因组质粒表达文库 ,库容量为 1 0 2× 1 0 5CFU。再用经过结核分枝杆菌和大肠杆菌的裂解产物吸附过的结核病人血清 ,通过原位免疫印迹来筛选基因组表达文库 ,共获得 1 6个阳性克隆。对阳性克隆进行测序和生物信息学分析 ,发现该 1 6个阳性克隆可能包含 2 2个开放阅读框 (ORF)。按照功能将其分为 7类基因 :脂类代谢 2个、信号途径 5个、PE/PPE蛋白家族 2个、中间产物与能量代谢 6个、细胞壁与细胞处理 1个、假想蛋白 4个和与牛型分枝杆菌定向进化同源的 2个 ,其中部分基因可能与毒力相关 ,可以作为候选药物靶标