功率超声对酶促反应的影响

本文评述了功率超声在水溶液和有机中对酶促反应的影响,对固定化酶的影响,同时探讨了功率超声影响酶促反应的可能机理,并并评价功能超声作为一种工业生物化学反应促进手段的可能性。     

壳聚糖固定化脲酶活性的X射线微区分析

利用X射线微区分析方法,对壳聚糖固定化脲酶活性进行了定位分析。筛选出了能捕捉固定化脲酶活性部位的捕捉剂BaCl₂,以尿素作为底物,在Tris-HCl缓冲溶液中,底物经固定化脲酶催化产生NH₃和CO₂,后者和捕捉剂反应生成BaCO₃沉淀, 沉积在固定化脲酶的催化活性部位,借此确定其催化活性部位。结果表明BaCl₂可用做固定化脲酶活性定位的捕捉剂。同时得到了壳聚糖固定化脲酶活性定位的最佳实验条件。     

超声波对木瓜蛋白酶催化活性影响的机理研究

木瓜蛋白酶经适当参数的超声波处理后酶活力提高。超声处理后酶的米氏常数Km变小,最大反应速率Vm也减小。超声处理后酶的紫外吸收光谱不变,荧光发射光谱也不改变,而差示光谱出现明显的正峰和负峰。研究结果表明,超声波处理后,木瓜蛋白酶的构型没有改变,而构象发生了变化。本文讨论了超声波影响木瓜蛋白酶活性的可能机理。     

超声波对多聚糖结构特性的影响

本文以灵芝为主要对象研究了多糖结构和微晶束结构及其稳定性和抗解性，通过对加超声能量场，对结晶结构施加强烈的机构冲击，使稳定性和抗解性消弱。     

岩石特性对超声波传播速度的影响

通过声速测定实验仪及数字示波器等装置测量了超声波在岩石中的传播速度,并对岩石成分、孔隙度、吸水量以及岩石温度等参数对超声波传播速度的影响进行了分析.结果表明,岩石孔隙度对超声波传播速度影响较大.同时,超声波传播速度随着岩石吸水量和环境温度的升高,传播速度呈现增大趋势.     

固体隔声层对超声波传播的影响实验研究

本文对测量固体隔声层对超声波传播发生影响的实验装置进行了介绍 ,并进行了实际测量 ,理论和实验结果相符较好     

超声波对丰年虫卵孵化的影响

研究了固定频率和强度的超声波对饵料生物丰年虫卵（ｃｈｉｒｏｃｅｐｈａｌｕｓ）化的影响。实验结果表明,在适宜的超声波辐照下,丰年虫卵的孵化率比对照组提高８％,孵化时间提前２ｈ。     

冷却与低温保存对小麦酯酶活性的影响

为研究小麦酯酶作为检测农药残留量生物传感器的生物敏感元件的可行性,研究了小麦酯酶在室温(20℃)和4℃保存时、在经历低温后及在液氮中保存后酶活性的变化情况。研究显示,小麦酯酶在室温和4℃保存时,其活性衰退较快,有必要对其进行低温保存;在液氮中停留20min或保存34h后,小麦酶活性仍能维持很高;在液氮中保存8天,活性仍有97.5％。     

超声波对池沸腾换热影响

对不同超声强度和辐射距离条件下过冷池沸腾换热特性进行了实验研究.超声波有效强化了沸腾起始段换热,对高热流密度沸腾传热也有一定的强化作用.超声辐射距离越近,强度越大,强化传热效果越好.对单相对流和沸腾起始区传热,超声波强化传热机理为空化作用;高热流密度沸腾时超声波对强化传热的主要机理是声流作用.得到了传热实验关联式.     

强化管型对超声波除垢影响的实验研究

结垢问题长久存在于电力、化工、石油等领域,将超声波应用在除垢上具有十分显著的优势。为研究不同管道内结垢和超声波除垢情况,本文采用实验方法,针对三种不同形状(圆管、波纹管和横纹管)管道进行结垢和超声波除垢研究。结果表明,波纹管内结垢量较其它两根管较少,而横纹管的超声波除垢效率最高。由此,可为工程实际中特殊管道的除垢及传统圆管可否进行管型改进提供一定的理论依据。     

超声辐照对酶促反应影响的研究进展

综述了超声辐照对于酶活性和酶催化反应的影响,以及各种超声参数对反应的影响,并展望了超声辐照在酶促反应中的应用前景。     

Mechanism study of dual-frequency ultrasound assisted enzymolysis on rapeseed protein by immobilized Alcalase

The mechanism of ultrasound field promoting enzymolysis efficiency is difficult to study, because the reaction system mixes with enzymes, proteins and hydrolysates. Immobilized enzyme is a good option that can be used to investigate the mechanism by separating enzymes out from the system after enzymolysis. The objective of this study was by using immobilized Alcalase to investigate the effects and mechanisms of the promotion of dual-frequency ultrasound (DFU) assisted-enzymolysis on rapeseed protein. Based on single factor experiments, response surface methodology model with three factors – hydrolysis time, power density and solid–liquid ratio at three levels was utilized to optimize the degree of hydrolysis (DH). Circular dichroism (CD) was used to analyze the secondary structure change of the protein, scanning electron microscopy (SEM) was used to analyze the surface microstructure change of the enzyme. The results showed that with DFU assisted-enzymolysis, the DH increased by 74.38% at the optimal levels for power density 57 W/L, solid–liquid ratio 5.3 g/L and enzymolysis time 76 min. After DFU assisted-enzymolysis, the yield of soluble solids content, including protein, peptides and total sugar in hydrolysate increased by 64.61%, 40.88% and 23.60%, respectively. CD analysis showed that after DFU assisted-enzymolysis, the number of α-helix and random coil decreased by 10.7% and 4.5%, β-chain increased by 2.4%. SEM showed that the degree of surface roughness of immobilized Alcalase increased. The above results indicated that the improvement of hydrolysis by DFU assisted-enzymolysis was achieved by enhancing the solid solubility, changing the molecular structure of protein and increased the surface area of immobilized enzyme.     

Interaction of therapeutic ultrasound with purified enzymes in vitro

The effects of ultrasound on the rates of the catalytic reactions of four purified enzymes in vitro have been extensively investigated under a wide range of biochemical and physical exposure conditions. In general, it can be concluded that therapeutic intensities of continuous wave 0.88 MHz ultrasound had no detectable direct effects on the rates of the reactions catalysed by creatine kinase, lactate dehydrogenase, hexokinase and pyruvate kinase. Some minor effects were noted. These were: an indirect effect resulting from mixing within the sample chamber caused by quartz wind streaming; an effect on partially-hydrated cross-linked enzyme systems which appears to be the result of increased fluid penetration of the solid matrix in the presence of ultrasound; and an increase in the rate of spontaneous dissociation of a multimeric enzyme system. It is, therefore, concluded that a direct interaction between ultrasound and the catalytic functioning of individual enzyme molecules is unlikely to be the primary step in any acousto-biological interaction, and that this primary interaction appears to be occurring at a higher level of organizational complexity.     

Effect of ultrasound on protein functionality

The review focus on the effect of ultrasound on protein functionality. The presence of transient ultrasonic mechanical waves induce various sonochemical and sonomechanical effects on a protein. Sonochemical effects include the breakage of chains and/or the modification of side groups of aminoacids. Sonomechanical modifications by enhanced molecular agitation, might lead to the transient or permanent modification of the 3D structure of the folded protein. Since the biological function of proteins depends on the maintenance of its 3D folded structure, both sonochemical and sonomechanical effects might affect its properties. A protein might maintain its 3D structure and functionality after minor sonochemical effects, however, the enhanced mass transfer by sonomechanical effects might expose internal hydrophobic residues of the protein, making protein unfolding to an irreversible denatured state. Ultrasound enhanced mass transport effects are unique pathways to change the 3D folded structure of proteins which lead to a new functionality of proteins as support shield materials during the formation microspheres. Enzymes are proteins and their reactions should be conducted in a reactor set-up where enzymes are protected from sonic waves to maximize their catalytic efficiency. In this review, focused examples on protein dispersions/emulsions and enzyme catalysis are given.     

Study of cell killing effect on S180 by ultrasound activating protoporphyrin IX

The present study was initiated to investigate the potential biological mechanism of cell killing effect on isolate sarcoma 180 (S180) cells induced by ultrasound activating protoporphyrin IX (PPIX). S180 cells were exposed to ultrasound for 30 s duration, at a frequency of 2.2 MHz and an acoustic power of 3 W/cm² in the presence of 120 μM PPIX. The viability of cells was evaluated using trypan blue staining. The generation of oxygen free radicals in cell suspensions was detected immediately after treatment using a reactive oxygen detection kit. A copper reagent colorimetry method was used to measure the level of FFAs released into cell suspensions by the process of cell damage induced by ultrasound and PPIX treatment. Oxidative stress was assessed by measuring the activities of key antioxidant enzymes (i.e., SOD, CAT, GSH-PX) in S180 tumor cells. Treatment with ultrasound and PPIX together increased the cell damage rate to 50.91%, while treatment with ultrasound alone gave a cell damage rate to 24.24%, and PPIX alone kept this rate unchanged. Colorimetry and enzymatic chemical methods showed that the level of FFAs in cell suspension increased significantly after the treatment, while the activity of all the above enzymes decreased in tumor cells at different levels, and were associated with the generation of oxygen free radicals in cell suspension after treatment. The results indicate that oxygen free radicals may play an important role in improving the membrane lipid peroxidation, degrading membrane phospholipids to release FFAs, and decreasing the activities of the key antioxidant enzymes in cells. This biological mechanism might be involved in mediating the effects on S180 cells and resulting in the cell damage seen with SDT.     

Synergism between ultrasonic pretreatment and white rot fungal enzymes on biodegradation of wheat chaff

Lignocellulosic biomass samples (wheat chaff) were pretreated by ultrasound (US) (40 kHz/0.5 W cm⁻²/10 min and 400 kHz/0.5 W cm⁻²/10 min applied sequentially) prior to digestion by enzyme extracts obtained from fermentation of the biomass with white rot fungi (Phanerochaete chrysosporium or Trametes sp.). The accessibility of the cellulosic components in wheat chaff was increased, as demonstrated by the increased concentration of sugars produced by exposure to the ultrasound treatment prior to enzyme addition. Pretreatment with ultrasound increased the concentration of lignin degradation products (guaiacol and syringol) obtained from wheat chaff after enzyme addition. In vitro digestibility of wheat chaff was also enhanced by the ultrasonics pretreatment in combination with treatment with enzyme extracts. Degradation was enhanced with the use of a mixture of the enzyme extracts compared to that for a single enzyme extract.     

超声波对菠萝果蛋白酶活性和光谱的影响

以菠萝果为材料，用盐析法制备菠萝果蛋白酶粗酶，进一步经SephadexG-50和DEAE-纤维素柱层析纯化，其SDS—PAGE呈单一的电泳带，并获得了菠萝果蛋白酶结晶。一定参数的超声作用可以使酶活力提高，经光谱分析，超声处理后酶的吸收光谱不改变，而荧光发射峰由336nm红移到339nm，紫外差示光谱在一定的波长也呈现出明显的正峰和负峰。本文讨论了超声波影响菠萝果蛋白酶活性的机理。     

Effect of ultrasound on the immunogenic corn cob xylan

Changes in the structural, molecular and functional properties of the immunogenic corn cob xylan evoked by ultrasonication in water, 1% NaOH and 5% NaOH were investigated. The reduction of the high molar mass (MM) fraction was more intense than that of the medium MM fraction, depending on the sonic power, sonication time, and alkali concentration. The chain degradation was more effective in the alkaline media. The UV-absorbing component, accompanying the xylan polymers in the whole MM range, showed an accumulation in the high MM region as well as shiftening to higher sizes, particularly in 5% NaOH. The sugar composition and primary structure of the xylan was almost retained under all irradiation conditions studied. Although the biological activity of the xylan was affected by the ultrasound, no significant decrease of the biological response was found at short irradiation time and low sonic power.