全细胞脂肪酶研究进展

脂肪酶是一类重要的工业用酶,广泛应用于诸多工业领域。与游离脂肪酶、物理或化学固定化脂肪酶相比,全细胞脂肪酶具有制备简单、无需蛋白质提取纯化、天然固定化、稳定性及抗逆性更好、制备及设备成本较低等优点,因此以全细胞形式利用脂肪酶被誉为是最有前景的降低生物转化成本的方法之一,关于全细胞脂肪酶的研究一直是脂肪酶领域的热点。就全细胞脂肪酶的研究进展进行归纳和述评,包括野生型全细胞脂肪酶和基因工程全细胞脂肪酶,并对其未来研究方向做出展望,以期为后续研究提供有益参考。     

假单胞菌属脂肪酶的分子生物学研究进展

微生物脂肪酶是商品化脂肪酶的主要来源,并广泛应用于诸多工业领域。与其他微生物脂肪酶相比,细菌脂肪酶催化反应的类型更多、活性更高、稳定性更好,其中又以假单胞菌属(Pseudomonas)脂肪酶的性能最为优越。作为性能最为优越、应用最为广泛的一类脂肪酶,假单胞菌属脂肪酶研究一直是脂肪酶领域的热点。就假单胞菌属脂肪酶的分子生物学研究进展进行归纳和述评,包括基因资源挖掘及克隆、基因表达调控及分泌机制、活性过表达策略、蛋白质结晶及3D结构解析、蛋白质工程,并对其未来研究方向做出展望,以期为后续研究提供有益参考。     

Recent Advances in the Understanding of Acupuncture

The controversy about acupuncture is familiar to us since its recent reintroduction into this country. Much of its philosophical concepts were taken at their face values as the bases for condemnation. Since I last reviewed these antiquated concepts in the light of modern medicine, much has developed. It seems that if the effects of acupuncture were transmitted along the peripheral nerves to the central nervous system, it would be more effective if applied segmentally to the site of noxious stimulation. Disruption of extralamniscal pathways would abolish its analgesic effect. The distant and nonsegmentally located acupuncture points exert their influences through the integrative efforts of the reticular formation and the thalamus. The demonstration of transmissibility of acupuncture analgesia through blood and cerebrospinal fluid in animals implicates the involvement of humoral factors. Since such an effect can be suppressed by naloxone or by hypophysectomy, endorphins are thought to be involved. Such laboratory evidences indeed begin to shed some light on a possible neurohumoral mechanism of acupuncture. The differences between acupuncture and hypnosis are discussed. Acupuncture points were compared with referred pain, trigger points and motor points of the skeletal muscles. Its possible uses for other than pain, such as drug addiction, alcoholism, etc. are also reviewed.     

Recent Advances in Understanding Biofilms of Mucosae

Extensive information on biofilm formation on different mucosal surfaces, particularly those of bacteria, have been accumulated. Different body sites such as body cavities, organs and tracts can become colonized by a variety of microbial species, but which are specific for the location. Biofilms of mucosae can aid colonization and contribute to pathogenesis, and are produced by microbial persistence on artificial abiotic surfaces which are implanted or by direct biofilm formation on biotic surfaces of tissues or organs. Such aspects of biofilms are discussed in this review.     

Recent Advances in the use of Immobilized Lipases Directed Toward the Asymmetric Syntheses of Complex Molecules

Water-insoluble compounds can be substrates for enzymatic reactions when lipases are immobilized properly and suitable organic solvents are used. In this review, three type of lipase immobilization method and their application to the asymmetric syntheses of complex molecules are described. Lipases immobilized with Celite or synthetic prepolymers such as urethane prepolymer and photo-crosslinkable resin prepolymer have been applied for the kinetic resolution of many kinds of water-insoluble substrate.

Phospholipid-lipase aggregates with ether linkages are novel and have been found to function effectively as immobilized lipases in asymmetric hydrolysis or esterification reactions in water-saturated organic solvent. The phospholipid-lipase aggregates are considered to have a stacked bilayer based on X-ray diffraction analysis structure of the lipid in the crystalline phase.     

Lipases in lipophilization reactions

Lipases are used in various sectors, as pharmaceutical, food or detergency industry. Their advantage versus classical chemical catalysts is that they exhibit a better selectivity and operate in milder reaction conditions. Theses enzymes can also be used in lipophilization reactions corresponding to the grafting of a lipophilic moiety to a hydrophilic one such as sugar, amino acids and proteins, or phenolic compounds. The major difficulty to overcome in such enzyme-catalyzed reaction resides in the fact that the two involved substrates greatly differ in term of polarity and solvent affinity. Therefore, several key parameters are to be considered in order to achieve the reaction in satisfactory kinetics and yields. The present review discusses the nature of such parameters (eg solvent nature, water activity, chemical modification of substrates) and illustrates their effect with examples of lipase-catalyzed lipophilization reactions of various sugar, amino acids or phenolic derivatives.     

Lipases for biotechnology

Lipases constitute the most important group of biocatalysts for biotechnological applications. The high-level production of microbial lipases requires not only the efficient overexpression of the corresponding genes but also a detailed understanding of the molecular mechanisms governing their folding and secretion. The optimisation of industrially relevant lipase properties can be achieved by directed evolution. Furthermore, novel biotechnological applications have been successfully established using lipases for the synthesis of biopolymers and biodiesel, the production of enantiopure pharmaceuticals, agrochemicals, and flavour compounds.     

Advances in the Understanding and Treatment of Head Injury

The author describes his personal involvement in head injury prevention and management over the past 40 years. He reviews the evolution of knowledge concerning the role of increased intracranial pressure, and considers the importance of cerebral vasoparalysis in the production of signs and symptoms following head injury, and the development of methods of recording intracranial pressure continuously, over hours and days.The development of an experimental compression model has led to a fuller understanding of edema of the brain and has provided a means of studying, by light and electron microscopy, the histological changes that result from edema. More recently, analyses of biochemical changes and disturbed membrane function have opened up a new avenue of potential treatment. Moreover, it is now clear that cerebral vascular dilatation and abrupt pressure increase can be produced in the monkey, in over 50% of cases, by lesions in the dorsomedial nucleus of the hypothalamus. Similar lesions may occur in the human and this suggests other therapeutic approaches. There is, then, a genuine hope of a breakthrough in the management of head injuries.     

深部脑刺激作用机制的研究进展

深部脑刺激(deep brain stimulation,DBS)已在临床上广泛用于治疗帕金森病等疾病引起的运动障碍,它在难治性癫痫、顽固性强迫症等其他脑中枢神经系统疾病的治疗上也展现出良好的应用前景.经过30多年的临床应用、动物实验和计算模型仿真等多方面的研究,DBS的机制也逐渐明朗.虽然尚无定论,但已取得许多重要进展.本文从电生理角度分析和总结了有关DBS机制的发展历程.从早期的抑制论和兴奋论到目前主导的调控论;从关注刺激位点的神经元活动,到发现神经元胞体与轴突活动的去耦合,再到高频刺激诱导的间歇性轴突阻滞,以及由此轴突活动可能导致的投射区神经元群体的去同步活动.这一系列研究进展表明DBS具有复杂的神经网络调控机制.了解DBS的作用机制对于提高其疗效、开发新刺激模式以及扩大临床应用的范围都具有重要意义.     

微生物脂肪酶蛋白质工程*

微生物脂肪酶催化的化学反应具有严格的立体选择性、位点选择性等专一性,催化活性高而副反应少,催化反应不需要辅助因子等特点,因此广泛应用于工农业生产中的诸多领域。利用蛋白质工程技术,提高微生物脂肪酶的特异性、活性和稳定性,对提高微生物脂肪酶制剂产品的市场竞争能力,扩大微生物脂肪酶的应用领域,具有重要的意义。综述了蛋白质工程技术在微生物脂肪酶改性方面的应用现状、存在问题及前景。     

Studies on Mucor Lipases

Mucor lipolyticus Aac-0102, a new species of Mucor, accumulated lipase in culture fluid when grown in a medium composed of soluble starch, soy bean meal, (NH₄)₂SO₄, and K₂HPO₄. This strain was the most lipolytic of the genus Mucor surveyed.

The culture fluid of this strain hydrolyzed various kinds of fatty acid esters, such as glycerides, Tweens or Spans and optimum activity for the hydrolysis of olive oil occurred at pH 8.0. This pH optimum was common to the lipases of the type cultures Mucor tested. The lipase of Mucor species may be different from that of Rhizopus species or other molds, since their pH optima are not the same.     

Lipases as practical biocatalysts

Lipases are the most used enzymes in synthetic organic chemistry, catalyzing the hydrolysis of carboxylic acid esters in aqueous medium or the reverse reaction in organic solvents. Recent methodological advancements regarding practical factors affecting lipase activity and enantioselectivity are reviewed. Select practical examples concerning the use of lipases in the production of chiral intermediates are also highlighted.     

Studies on Mucor Lipases

Lipases produced by Mucor lipolyticus Aac-0102 were separated into three different fractions (F-1, F-2 and F-3) by CM-Sephadex column chromatography.

Molecular weights of them were estimated to be higher in the order of F-1, F-2, and F-3 by gel filtration on a Sephadex G-100 column. F-1 and F-2 could hydrolyze water soluble substrate such as Tweens. F-3 showed a strong hydrolytic activity toward triglycerides but the activity toward Tweens was almost negligible.

Sodium lauryl sulfate inhibited the olive oil hydrolyzing activity of F-3. However, Tween hydrolyzing activity of F-2 was not affected with it. These results suggested that they are different with each other with respect to their molecular weights, substrate specificities and sensitivities to some inhibitors.     

石杉碱甲结构改造的研究进展

石杉碱甲是高效、高选择性的可逆性乙酰胆碱酯酶抑制剂,是治疗早老性痴呆症的一个有前景的药物.本文概述了石杉碱甲的性质、结构和构效关系,从结构简化、C10、吡啶酮环、脂桥环、环外双键和桥头氨基等方面综述了石杉碱甲结构改造的研究进展,并描述了所得的新型石杉碱甲类似物的抗乙酰胆碱酯酶的生物活性.在已合成的大量的石杉碱甲类似物中,部分类似物的活性优于天然石杉碱甲,石杉碱甲结构改造的研究取得了可喜的进展.     

Lipases in autolysed cultures of filamentous fungi

Fifty-one fungi from different genera and strains were checked in plate to determine lipase activity in protein precipitates from their autolysed cultures. Each of them was then analysed at 3·5, 6·5 and 9·2 pH units and, as a consequence, basic lipases with high activity at 9·2 pH were found after 1 h of incubation. Only 25% of the studied fungi showed this lipase activity, among them the best producers were fungi from genus Fusarium (47% of fungi had lipase activity). In addition to lipase activity, Fusaria showed a low hydrolytic activity on cutin and suberin. The genus Aspergillus produced lipase and cutinase activity to a similar extent. Aspergillus nidulans 2544 also showed suberinase activity in a considerable amount. Penicillium species had very low activities. Other species and strains from genus Trichoderma , order Mucorales and class Basidiomycetes, did not show lipase activity in their degradative processes.     

Lipases in catalytic reactions of organic chemistry

Aspects of enzymatic catalysis in lipase-catalyzed reactions of organic synthesis are discussed in the review. The data on modern methods of protein engineering and enzyme modification allowing a broader range of used substrates are briefly summarized. The application of lipase in the preparation of pharmaceuticals and agrochemicals containing no inactive enantiomers and in the synthesis of secondary alcohol enantiomers and optically active amides is demonstrated. The subject of lipase involvement in the C-C bond formation in the Michael reaction is discussed. Data on the enzymatic synthesis of construction materials—polyesters, siloxanes, etc.—are presented. Examples demonstrating the application of lipase enzymatic catalysis in industry are given.     

Lipases from psychrotropic antarctic bacteria

Abstract Properties of lipases excreted by 4 psychrotropic Moraxella strains from antarctic sea water have investigated. Despite an optimal cell generation time at 25°C, maximal lipase excretion essentially occurs at low temperatures. These enzymes are characterized by a shift of the apparent optimal activity towards low temperatures, by a reduction of the activation energy value and by a decrease in heat stability. These lipases are associated with lipopolysaccharides, forming high molecular weight complexes. One of the selected strain is able to express the antibiotic resistances carried by RP4, at both 4 and 25°C.