共查询到20条相似文献，搜索用时 46 毫秒
1.
建立了聚合度2～10的壳寡糖的薄层层析分析(TLC)方法,在异丙醇∶水∶氨水=60∶30∶4的展开体系中,各壳寡糖可以得到很好的分离,各单体间比移值(Rf)差异明显,无拖尾现象。通过对比TLC法与高效液相色谱(HPLC)法分析壳寡糖单体的效果,得出TLC法具有快速、有效、方便的优点,可以作为定性分析壳寡糖单体纯度的方法。采用本实验室制备的壳聚糖酶对3种不同脱乙酰度的壳聚糖和DP2～6的壳寡糖进行水解,采用TLC法对水解产物进行分析。实验结果表明,随着壳聚糖脱乙酰度的降低,其酶水解产物的糖链延长。该壳聚糖酶不能水解DP2～4的壳寡糖,对DP5～6的壳寡糖水解速率缓慢。通过对该壳聚糖酶作用特点分析,表明该酶可作用于GlcN-GlcN糖苷键,而不能水解Glc-NAc-GlcNAc糖苷键。 相似文献
2.
壳聚糖酶的分离纯化及性质研究 总被引：4，自引：0，他引：4
以本实验室分离的产壳聚糖酶YJ02菌株出发,制备壳聚糖酶发酵液,经离心、(NH4)2SO4分级盐析、Q-SepharoseFast Flow阴离子交换、Sephacry S-100凝胶过滤分离纯化步骤,SDS-PAGE显示为一条带,壳聚糖酶纯化了28.9倍,收率为47.6%。该酶的性质研究表明,该酶的分子量为66.2KD,最适反应温度为50℃,最适反应pH为6.0;Mn2 对酶活力有明显的促进作用,Cu2 ,Fe3 ,Hg2 对酶活力有抑制作用;小分子有机物EDTA和SDS对酶活力有抑制作用,而IAA和β-巯基乙醇对酶活力稍有促进作用。该壳聚糖酶对高脱乙酰度壳聚糖底物水解作用强,酶解位点可能为NGlc-NGlc,酶最大反应速度Vmax=4.1μmol/min,常数Km为64mmol/L。此壳聚糖酶水解壳聚糖制备的壳寡糖数均分子量为2 400Da。 相似文献
3.
不结球白菜叶片壳聚糖酶的理化特性研究 总被引：3，自引：0，他引：3
通过不结球白菜叶片壳聚糖酶对壳聚糖的降解,研究了温度、pH、时间及金属离子等对此壳聚糖酶的影响。结果表明,壳聚糖酶的最适温度为45℃,最适pH为5.5,酶促反应速度在6 h内达到最大值;Mn2 和Cu2 对壳聚糖酶促反应分别起到促进和抑制的作用。经薄板层析分析证实,壳聚糖酶降解壳聚糖为低聚物。 相似文献
4.
5.
壳聚糖酶基因在解脂耶氏酵母中的表达及重组酶性质研究 总被引：1，自引：0，他引：1
为构建高效表达壳聚糖酶工程菌株,以Microbacteriumsp.基因组为模板扩增壳聚糖酶基因,目的基因与表达载体pINA1317连接构建重组质粒,重组质粒NotⅠ酶切线性化后转化解脂耶氏酵母Y.liPolytica Po1h。所得结果为PCR扩增得到约1000bp的特异性片段,序列分析表明含有壳聚糖酶全长基因,开放阅读框801bp,编码266个氨基酸残基。转化子酶活力为10.4U/mL,是原菌株酶活力的3.15倍。重组蛋白经DEAE-Sepharose FF分离纯化,达到电泳纯,SDS-PAGE显示单一条带,分子量约41kDa。重组酶反应最适温度为45℃,最适pH为5.6,Km和Vmax分别是0.926mg/mL和6.15U/mL。质谱分析酶解产物主要为三糖和五糖。实现了壳聚糖酶在解脂耶氏酵母中的分泌表达,为壳聚糖酶的工业化生产奠定了理论基础。 相似文献
6.
高产壳聚糖酶菌株的筛选和发酵产酶条件研究 总被引：13，自引：1，他引：12
为探讨专一性地降解甲壳质或壳聚糖的甲壳质酶或壳聚糖酶 ,从采集的土样中分离到 4株产壳聚糖酶能力较强的菌株 ,经摇瓶复筛 ,菌株YJ0 2产酶能力最强。对其发酵产酶条件的研究结果表明其产酶最适培养基组分为 (% ,w/v) :粉末壳聚糖 2 .0 ,葡萄糖 0 .1,NH4NO3 1.0 ,酵母提取物 0 .5 ,K2 HPO40 .0 7,KH2 PO40 .0 3 ,NaCl0 .5 ,MgSO4·7H2 O 0 .0 5 ,起始 pH 6.0。最适产酶培养条件是 :5 0 0mL三角烧瓶装瓶量为 15 0mL ,2 .0 % (v/v)接种量 ,3 0℃ ,15 0r/min培养 72h。在最适产酶培养条件下 ,72h时菌株YJ0 2发酵液中壳聚糖酶活力可达到 17.0 4U/mL。 相似文献
7.
烟曲霉产壳聚糖酶液体发酵条件研究 总被引：6，自引：0，他引：6
以烟曲霉(Aspergillus fumigatus)为出发菌,通过选择适合的培养条件,筛选出产壳聚糖酶的菌株。实验结果表明,烟曲霉是良好的产壳聚糖酶出发菌。烟曲霉液体发酵产壳聚糖酶最适培养基组成为:壳聚糖1%,KH2PO40.06%,尿素0.2%,(NH4)2SO40.1%,MgSO40.012%,20%土豆汁3%,NaCl 0.05%。在pH 5.0、温度28℃、摇床转速120 r/min培养条件下振荡培养3 d,烟曲霉产壳聚糖酶的能力最强,达25.1 U/mL。 相似文献
8.
海洋生物体内蕴含着丰富的天然活性物质,许多都具有抑菌活性,据此研制新型海洋生物源抑菌药物,是海洋生物产业中的一个新领域,也是新型抑菌药物研发的重要途径。壳聚糖是来自海洋中虾蟹等甲壳类动物外壳的甲壳素的脱乙酰产物,壳寡糖是壳聚糖的降解产物,具有比壳聚糖更好的水溶性和生物活性,在食品和生物医药等领域具有更广阔的应用前景。为了提高壳寡糖的抑菌活性,本研究以壳寡糖和烟酸为原料、N, N-羰基二咪唑为催化剂合成了壳寡糖烟酸接枝衍生物,并与不同链长的溴代烷烃亲核反应得到其阳离子化衍生物。壳寡糖及其衍生物的化学结构通过红外光谱(FTIR)和核磁共振波谱(NMR)进行分析表征,壳寡糖及其衍生物对2种海洋致病细菌和3种植物致病真菌的体外抑菌能力分别采用肉汤稀释法和菌丝生长速率法进行研究和评估。结果表明,与壳寡糖相比,合成的终产物对致病菌的抑制能力得到了极大增强,其中含有己基的烟酰化壳寡糖季铵盐表现出最强的抑制海洋致病细菌活性(MIC=0.125mg/mL、MBC=0.25mg/mL),并且该化合物表现出较强的抗真菌活性,在1.0 mg/mL时,对灰葡萄孢菌和围小丛壳的抑制率分别为65.7%和51.5%。... 相似文献
9.
探讨了壳寡糖及全乙酰壳寡糖的制备方法,通过正交实验考察了原料、温度、时间对降解产物的影响.制备了八种寡糖（八乙酰壳二糖、十一乙酰壳三糖、十四乙酰壳四糖和十七乙酰壳五糖,以及N,N′-二乙酰壳二糖、N,N′,N″-三乙酰壳三糖、N,N′,N″,N′′′四乙酰壳四糖和N,N′,N″,N′′′,N′′′′-五乙酰壳五糖）,并通过IR、NMR及MS等确定了其化学结构. 相似文献
10.
采用氧化降解和酶降解两种方法制备壳寡糖.并对降解产物的氨基质量分数变化,平均分子质量进行了分析和测定.结果表明,氧化降解法降解速率快,降解产物的平均分子质量都低于2 ku,但降解产物的氨基质量分数均有部分损失;酶法降解产物的氨基含量基本没有损失,但酶法降解的时间较长,得到的产物平均分子质量较高.分别采用木瓜蛋白酶和纤维素酶时壳聚糖进行降解,经过24 h降解,平均分子质量从630 ku分别降至43 ku和25 ku左右,表明纤维素酶的水解能力强于木瓜蛋白酶. 相似文献
11.
Chandralata Raghukumar G. Sheelu P. A. Loka Bharathi Shanta Nair C. Mohandass 《Marine Georesources & Geotechnology》2001,19(1):1-16
In order to assess the impact of deep-sea mining on the in situ benthic life, we measured the microbial standing stock and concentration of organic nutrients in the deep-sea sediments of the Central Indian Ocean Basin in the Indian pioneer area. Sediments were collected using box core and grab samples during September 1996. The total bacterial numbers ranged from 10 10 -10 11 cells per g -1 dry weight sediment. There was a marginal decrease in the number of bacteria from surface to 30 cm depth, though the subsurface section registered a higher number than did the surface. The highest numbers were encountered at depths of 4-8 cm. The retrievable number of bacteria were two orders less in comparison with the direct total counts of bacteria. An almost homogeneous distribution of bacteria, total organic carbon, living biomass, and lipids throughout the depth of cores indicates active microbial and benthic processes in the deep sea sediments. On the other hand, a uniform distribution of total counts of bacteria, carbohydrates, and total organic carbon in all the cores indicates their stable nature and suggests that they can serve as useful parameters for long-term monitoring of the area after the benthic disturbance. Further studies on temporal variability in this region would not only verify the observed norms of distribution of these variables but would also help to understand restabilization processes after the simulated benthic disturbance. 相似文献
12.
Arne Schnack-Friedrichsen Angela M. Davis Jim D. Bennell Dei G. Huws 《Marine Georesources & Geotechnology》2001,19(4):221-243
The interdependence between the seismo-acoustic properties of a marine sediment and its geotechnical/physical parameters has been known for many years, and it has been postulated that this should allow the extraction of geotechnical information from seismic data. Though in the literature many correlations have been published for the surficial layer, there is a lack of information for greater sediment depths. In this article, a desktop study on a synthetic seafloor model illustrates how the application of published near-surface prediction equations to subsurface sediments (up to several tens of meters burial depth) can lead to spurious predictions. To test this further, acoustic and geotechnical properties were measured on a number of sediment core samples, some of which were subjected to loading in acoustically-equipped consolidation cells (oedometers) to simulate greater burial depth conditions. For low effective pressures (representing small burial depths extending to around 10 meters subsurface), the general applicability of established relationships was confirmed: the prediction of porosity, bulk density, and mean grain size from acoustic velocity and impedance appears generally possible for the investigated sedimentary environments. As effective pressure increases through, the observed relationships deviate more and more from the established ones for the near-surface area. For the samples tested in this study, in some instances increasing pressure even resulted in decreasing velocities. There are several possible explanations for this abnormal behavior, including the presence of gas, overconsolidation, or bimodal grain size distribution. The results indicate that an appropriate depth correction must be introduced into the published prediction equations in order to obtain reliable estimates of physical sediment properties for greater subsurface depths. 相似文献
13.
Geoacoustic Inversion via Genetic Algorithm and Its Application to Manganese Sediment Identification
An acoustic inversion method using a wide-band signal and two near field receivers is proposed and applied to multiple layered seabed models including a manganese sediment. The inversion problem can be formulated into a probabilistic model comprised of signals, a forward model, and additive noise. The forward model simulates wide-band signals, such as chirp signals, and is chosen to be the source-waveletconvolution plane wave modeling method. The wavelet matching technique, using weighted least-squares fitting, estimates the sediment sound-speed and thickness on which determination of the possible numerical ranges for a priori uniform distribution is based. The genetic algorithm is applied to a global optimization problem to find a maximum a posteriori solution for determined a priori search space. Here the object function is defined by an L 2 norm of the difference between measured and modeled signals. Not only the marginal pdf but also its statistics are calculated by numerical evaluation of integrals using the samples selected during importance sampling process of the genetic algorithm. 相似文献
14.
海上大直径钢管桩打桩过程中,桩周土体受到强烈扰动而发生强度弱化,掌握桩周土体强度弱化规律对于准确预测打桩过程、保证工程安全具有重要意义。为研究土体强度弱化规律,开展了环剪试验模拟打桩对桩周土体的扰动,测试土体强度随剪切速率的变化规律,建立了描述土体强度弱化规律的拟合公式,引入到打桩分析软件中。研究结果表明：土体的强度折减程度不仅与土体本身的性质有关还受到土体的埋深和剪切速率的影响,埋深越深土体强度折减程度越低,剪切速率越高土体强度折减越高,在打桩分析中可采用这里推荐的线性折减方法来模拟不同深度处土体强度的折减规律。 相似文献
15.
Shigehisa Nakamura 《Marine Geodesy》2000,23(1):55-61
Specific properties of the interannual sea level variations and annual tides in the Northwestern Pacific were studied. Several tide stations were monitored. The monthly mean sea level for the year of 1995 was analyzed at each tide station. A seismic event in 1995, some tectonic activity around the subject area, and the Kuroshio (the oceanic western boundary current) may possibly contaminate results which would have occurred from the astronomical annual tide alone. 相似文献
16.
The effect of different fixation and storage protocols on the flow cytometric (FCM) simultaneous analysis of bacterioplankton and phytoplankton in coastal seawater samples (Mediterranean coastal lagoons) was investigated. FCM measurements (cell number, fluorescence and scatter characteristics) were obtained through DAPI staining. Three fixatives [glutaraldehyde (GA), formaldehyde (FA) and paraformaldehyde (PFA)] and two storage (3 months duration) methods (5 °C and −196 °C) were tested. Two dominant populations were detected in studied samples: bacteria and eukaryotic picophytoplankton. Adding fixatives (2% final concentration) appears necessary to obtain FCM exhaustive counts of all the bacteria and phytoplanktonic cells. This was related to the permeation effect of fixatives which allowed a better DAPI staining of the cells. Maximum fluorescence, i.e. optimal staining of the cells was obtained with FA or PFA, and significant lower fluorescences with GA. Fixed samples stored at 5 °C induced rapid cell loss. Only storage in liquid nitrogen of samples fixed with FA or PFA, allows mid-term (≥4 months) preservation of bacteria or picophytoplankton cell numbers, and limited evolution of DAPI-induced fluorescence and scatter characteristics. 相似文献
17.
18.
19.
《海洋学报(英文版)》2014,(9):F0003-F0003
<正>Acta Oceanologica Sinica(AOS)is a comprehensive academic journal edited by the Editorial Committee of Acta Oceanologica Sinica and is designed to provide a forum for important research papers of the marine scientific community which reflect the information on a worldwide basis.The journal publishes scholarly papers on marine science and technology,including physics,chemistry,biology, 相似文献
20.
Oedometer tests have been carried out on 70 undisturbed surficial clays (at approximately 250 mm below the mudline), mostly collected by free-fall corers from sites widely scattered throughout the deep-sea North Atlantic. Acoustic measurements were also made, initially on contiguous samples and ultimately on the same sample using a geophysically instrumented oedometer which also collected electrical resistivity data. Apart from those quiescent areas below the carbonate compensation depth, such as north of the West Indies where very fine clays exist, most of the samples are silty clays whose geotechnical-geophysical properties are dependent on the type of clay minerals present (and their ability to take in moisture), the sand-size fraction, and the quantity of carbonate present. Thus the pure clays have high compressibilities which decrease on the addition of coarse particles, while the converse is true for the acoustic parameters, these increasing with the sand fraction. Using the notion of the intrinsic compression line for all samples, and comparison to it of the measured compression curves, it is clear that, contrary to some previously held ideas, most deep-sea clays are normally consolidated; the addition of carbonate has the effect of creating an open, stronger sediment skeleton. Interestingly, where information is available, the variation with depth of a sample's acoustic velocity follows the void ratio pressure relationship of the compression curve. This allows the construction of an in-situ sediment compression curve using the in-situ geophysical observations. 相似文献