One hundred years of peptide chemistry

Emil Fischer is considered to be the founding father of the field of peptide chemistry and originator of the term peptide. In the beginning of the 20th century, Fischer had a clear vision to foresee the day when a protein would be synthesized. Subsequent to this brilliant beginning, progress however was slow for the next 50 years. In 1953, the chemical synthesis of oxytocin by duVigneaud was a landmark achievement. The subsequent decades witnessed the discovery of a vast number of biologically active peptides. The last two decades of the 20th century was filled with hopes of multiple simultaneous synthesis, peptide libraries and peptide vaccines. This article is a concise account of the types of family of peptides discovered and their biological role.     

One hundred years of peptide chemistry

Emil Fischer is considered to be the founding father of the field of peptide chemistry and originator of the term peptide. In the beginning of the 20th century, Fischer had a clear vision to foresee the day when a protein would be synthesized. Subsequent to this brilliant beginning, progress however was slow for the next 50 years. In 1953, the chemical synthesis of oxytocin by duVigneaud was a landmark achievement. The subsequent decades witnessed the discovery of a vast number of biologically active peptides. The last three decades saw development of multiple simultaneous syntheses, peptide libraries and peptide vaccines. This article is a concise account of the types of peptides discovered and their biological role.     

Preparation of protein samples for gel electrophoresis by sequential extraction

Since preparation and solubilization of protein samples are crucial factors in proteome research, the authors established a sequential extraction technique to prepare protein samples from the body wall of the 5th instar larvae of silkworm,Bombyx mori. Two kinds of protein samples were obtained from the body wall using the method. Between the two types of samples only about 15% proteins were identical; the majority were different, indicating that more species of proteins could be obtained with the sequential extraction method; which will be useful for preparation of protein samples for proteome study.     

Allosteric regulation of proteins

Allostery is a mechanism by which the activity of a large number of proteins is regulated. It is manifested as a change in the activity, either ligand binding or catalysis of one site of a protein due to a ligand binding to another distinct site of the protein. The allosteric effect is transduced by a change in the structural properties of the protein. It has been traditionally understood using either the concerted MWC (Monod, Wyman and Changeux) model, or the sequential KNF (Koshland, Nemethy and Filmer) model of structural changes. However, allostery is fundamentally a thermodynamic process and requires an alteration in the enthalpy or entropy associated with the process.     

化学二氧化锰研究进展

目的展望化学二氧化锰（CMD）工业的发展趋势,方法综述CMD的制备、改性等方面的研究进展情况,介绍几种常见的CMD合成法,结果随着研究的深入,新的化学工艺不断出现,化学二氧化锰的性能会越来越好,并将接近或超越电解二氧化锰（EMD）,结论CMD研究仍将是化学领域的热点之一.     

Structures of argumentative discourse: Effects of type of referential space

Written argumentative texts were collected from 7 to 14 year-old-children in two situations: one in which a scientific-like issue was to be debated (formal discourse: FD) and one in which an opinion was to be defended (natural discourse: ND). The structure of the supporting arguments advanced in the individual protocols were analyzed. Various structural indices were defined and calculated for each protocol, and then input into a factorial correspondence analysis. In both the FD and ND conditions, the main factorial axis opposes long protocols to short ones. This finding held true even though the other indices were weighted to compensate for protocol length. The length variable thus appears to be a discourse characteristic as such. Furthermore, long FD protocols were associated with embedded structures and a substantial amount of rewording. Long ND protocols had a low degree of embedding, and contained many accumulated arguments and thematic breaks. The second axis opposes sequential chaining of arguments to argument coordination in FD. In ND, it opposes the absence of structure and many rewordings to a variety of more or less highly organized structures, but without sequential chaining. These analyses revealed some interesting differences between formal and natural discourse: the key role played by sequential chaining in FD versus the insignificance of this type of structure in ND, and the important but different role of rewording in FD and ND. Protocol length was found to be strongly linked to subject age: older subjects have more arguments at their disposal. But in addition to acquiring the ability to write longer texts, older children are able to use different structures for argumentation, depending on the type of referential space involved.     

固相微萃取法与水蒸气蒸馏法提取白胡椒挥发油成分的比较

采用固相微萃取法和水蒸气蒸馏法提取白胡椒中挥发性化学成分,用气相色谱．质谱法确定挥发性化学成分结构及各化学成分在挥发油中的质量分数．分别鉴定出22种和24种化学成分．两种方法提取白胡椒挥发油中蒎烯、蒈烯、3,7-二甲基1,6-辛3-醇和石竹烯的含量均较高．     

Teaching Genetics in Secondary Classrooms: a Linguistic Analysis of Teachers’ Talk About Proteins

This study investigates Swedish biology teachers’ inclusion of proteins when teaching genetics in grade nine (students 15–16 years old). For some years, there has been a call to give attention to proteins when teaching genetics as a means of linking the concepts ‘gene’ and ‘trait’. Students are known to have problems with this relation because the concepts belong to different organizational levels. However, we know little about how the topic is taught and therefore this case study focuses on how teachers talk about proteins while teaching genetics and if they use proteins as a link between the micro and macro level. Four teachers were recorded during entire genetics teaching sequences, 45 lessons in total. The teachers’ verbal communication was then analyzed using thematic pattern analysis, which is based in systemic functional linguistics. The linguistic analysis of teachers’ talk in action revealed great variations in both the extent to which they used proteins in explanations of genetics and the ways they included proteins in linking genes and traits. Two of the teachers used protein as a link between gene and trait, while two did not. Three of the four teachers included instruction about protein synthesis. The common message from all teachers was that proteins are built, but none of the teachers talked about genes as exclusively encoding proteins. Our results suggest that students’ common lack of understanding of proteins as an intermediate link between gene and trait could be explained by limitations in the way the subject is taught.     

Network Structure Expert System and Operation Optimization

It is propsed that double level programming technique may be adopted in synthesis strategy ,Optimi-zation of heat exchanger network sturctural configuration (the master problem )may be solved at the upper level ,leaving the rest operaing conditions (the slave problem)being optimized at the lower level ,With the uniqueness in mind,an HEN synthesis expert system may be employed to address both the logical constraints and the global operation parameters‘ optimization using enhanced sequential number optimization theory,Case studies demonstrate that the synthesis strategy proposed can effectively simplify both the problem-solving and the synthesis process,The validity of the strategy recommended is evidenced by case studies‘ results compared.     

EFFECT OF OVARIAN STIMULATION WITH OR WITHOUT GnRH AGONIST ON HAMSTER ENDOMETRIAL SECRETION

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Effect of ovarian stimulation with or without GnRH agonist on hamster endometrial secretion

The present study was undertaken to evaluate the endometrial secretion and synthesis of proteins in hamsters that were subjected to ovarian stimulation with or without GnRH agonist (Leuprolide Acetate, LA). The results of protein resolution revealed that the molecular weight of the proteins increased from 31D to 66D, while the intensities of photographed protein bands in the hamsters treated with LA and pregnant mare’ s serum gonadotropin (PMSG) were less than that in those treated with PMSG alone. The amounts of low and medium weights (31kD and 45kD) proteins newly synthesized in LA+PMSG group and saline group (control) were significantly higher than that in PMSG group. The synthesized and secreted proteins in groups LA and control were similar. The data suggested that a physiologic endometrial protein secretory and synthetic change with GnRH agonist regarcded as a possible cause of the higher pregnancy rate in in vitro fertilization. The degree of endometrial secretion and synthesis varied considerably with the type of ovarian stimulation used. Project supported by China Medical Board of New York Inc., USA     

Adult word recognition and visual sequential memory

Two experiments were conducted investigating the role of visual sequential memory skill in the word recognition efficiency of undergraduate university students. Word recognition was assessed in a lexical decision task using regularly and strangely spelt words, and nonwords that were either standard orthographically legal strings or items made from words with internal transposed letters. Symbol memory was evaluated in a recognition procedure in which sequences of three to five unfamiliar complex symbols were presented, each followed by a subsequent array containing the symbols either in the same order or with an order transposition. In Experiment 1, there was no independent contribution of symbol memory to either word or nonword processing independently of the ability to discriminate the symbols from one another. In Experiment 2, although symbol memory made a significant contribution to word recognition independently of symbol discrimination and letter identification for two conditions??long strangely spelt words and short transposed-letter items, the effects were extremely small. It was concluded that non-verbal visual sequential memory skill does not play a central role in underpinning efficiency of word recognition in experienced adult readers.     

核糖体RNA的转录与调控

核糖体是细胞生长所需的蛋白质合成的动力工厂,每一个核糖体的大小为4兆而顿,有18S、5.8S、28S和5S四种RNA及80S等蛋白质组成,细胞中约有50%的RNA是核糖体RNA,这些RNA直接或间接地参与形成数百万的核糖体,因此,核糖体RNA基因的转录调控机制一直是细胞生长和细胞周期调控研究的热点,细胞通过进化已经形成一套完整的配合RNA聚合酶共同完成的核糖体RNA转录调控机制。本文从核糖体RNA基因结构出发,就染色质重塑、组蛋白乙酰化及细胞周期三个方面探讨核糖体RNA转录调控机制。     

Reading Strategies in Children with Cerebral Visual Impairment caused by Periventricular Leukomalacia

Four children with cerebral visual impairment caused by periventricular leukomalacia were followed in an ethnographic clinical case study for two years during their process of learning to read in mainstream classes. When compared to children with ocular visual impairment, children with cerebral visual impairment often exhibit an uneven cognitive profile with visuo-spatial deficits but good verbal capacities. One main problem for children with deficits due to periventricular leukomalacia is decreased visual acuity with crowding, that is, an inability to identify symbols in a line, while single symbols of the same size may be identified. A question addressed in the study is what kind of strategies does the child with "crowding" problems develop in reading long words in print. Could Braille, as a sequential reading medium, be an alternative for the child with simultaneous visual problems? Two children were offered both Braille and print reading as reading media, one of whom preferred Braille after two years of training. The other two children read ordinary print without any special teaching. After two years, considerable differences in reading acquisition and reading strategies could be detected among the four children. No single factor seemed to account for the differences. Individual factors as well as teaching methods could be reasons for the differences.     

Emerging role of protein modification in inflammatory bowel disease

The onset of inflammatory bowel disease (IBD) involves many factors, including environmental parameters, microorganisms, and the immune system. Although research on IBD continues to expand, the specific pathogenesis mechanism is still unclear. Protein modification refers to chemical modification after protein biosynthesis, also known as post-translational modification (PTM), which causes changes in the properties and functions of proteins. Since proteins can be modified in different ways, such as acetylation, methylation, and phosphorylation, the functions of proteins in different modified states will also be different. Transitions between different states of protein or changes in modification sites can regulate protein properties and functions. Such modifications like neddylation, sumoylation, glycosylation, and acetylation can activate or inhibit various signaling pathways (e.g., nuclear factor-κB (NF-κB), extracellular signal-regulated kinase (ERK), and protein kinase B (AKT)) by changing the intestinal flora, regulating immune cells, modulating the release of cytokines such as interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and interferon-γ (IFN-γ), and ultimately leading to the maintenance of the stability of the intestinal epithelial barrier. In this review, we focus on the current understanding of PTM and describe its regulatory role in the pathogenesis of IBD.

     

液滴微流控研究重要进展

芯片上生成的微流控液滴具有尺寸均一、体积小、生成速率快等特点,在化学和生物学上有广阔的应用前景．近年来液滴的质谱分析、液滴梯度的生成、双重液滴的生成与应用、液滴的基因筛选和蛋白质合成等取得了较大突破．液滴微流控正在发展成为化学、生命科学及医学等领域的重要研究平台．     

核糖体RNA的转录与调控

核糖体是细胞生长所需的蛋白质合成的动力工厂,每一个核糖体的大小为4兆而顿,有18S、5．8S、28S和5S四种RNA及80S等蛋白质组成,细胞中约有50％的RNA是核糖体RNA,这些RNA直接或间接地参与形成数百万的核糖体,因此,核糖体RNA基因的转录调控机制一直是细胞生长和细胞周期调控研究的热点,细胞通过进化已经形成一套完整的配合RNA聚合酶共同完成的核糖体RNA转录调控机制。本文从核糖体RNA基因结构出发,就染色质重塑、组蛋白乙酰化及细胞周期三个方面探讨核糖体RNA转录调控机制。     

氨基磺酸法合成十二烷基硫酸钠综合实验

十二烷基硫酸钠是阴离子硫酸酯类表面活性剂的典型代表,具有广泛的用途。十二烷基硫酸钠的合成制备是常见的化工专业实验,但存在合成时间长、产率低、产品稳定性差的缺点。该文对氨基磺酸法合成十二烷基硫酸钠专业实验进行了研究,在保证产率的基础上有效缩短了实验时间,并结合产品的提纯、分析和表征提高实验的综合性。     

Improvement in the Orthogonal Protein Degradation in Escherichia coli by Truncated mf-ssrA Tag

SsrA peptide tag from Mycoplasma florum has been developed as a versatile biotechnology tool to control orthogonal degradation of tagged proteins in Escherichia coli. Here, using the systematic deletion mutants of mf-ssrA tag, we demonstrated that the residues in two separate regions have different functions in mf-Lon-mediated specific orthogonal target protein degradation in E. coli. The deletion of multiple residues, up to six amino acids, did not fatally abolish its specific degradation activity, instead of being able to improve the stability of the tagged protein in the presence of endogenous proteases before mf-Lon expression in E. coli. Except for previously identified essential residues, the region adjacent to the C-terminal of the mf-ssrA tag was involved in mf-Lon and endogenous protease-mediated degradation. Moreover, the deletion of specific residues made the mf-ssrA tag more effective and compact. The mf-ssrA tag can be implemented in synthetic biology and bioengineering for development of synthetic circuits.