固定化单宁对酒类营养成分的吸附性能研究

采用固定化单宁对酒中可能存在的营养成分蛋白质、氨基酸、糖类、有机酸、乙醇和铁离子等进行吸咐试验。结果表明：固定化单宁对不同营养成分的吸附率差别明显，它通过氢键和疏水作用对蛋白质有较大的吸附率，通过多个酚羟基与中心铁离子形成螯合物而对其有较大的吸附率，对氨基酸、糖、有机酸和乙醇等营养成分或风味物质吸附率不大，固定化单宁可以作为一种较为理想的酒类处理剂。     

Development and application of an integrated system for monitoring ethanol content of fuels

An automated flow injection analysis (FIA) system for quantifying ethanol was developed using alcohol oxidase, horseradish peroxidase, 4-aminophenazone, and phenol. A colorimetric detection method was developed using two different methods of analysis, with free and immobilized enzymes. The system with free enzymes permitted analysis of standard ethanol solution in a range of 0.05–1.0 g of ethanol/L without external dilution, a sampling frequency of 15 analyses/h, and relative SD of 3.5%. A new system was designed consisting of a microreactor with a 0.91-mL internal volume filled with alcohol oxidase immobilized on glass beads and an addition of free peroxidase, adapted in an FIA line, for continued reuse. This integrated biosensor-FIA system is being used for quality control of biofuels, gasohol, and hydrated ethanol. The FIA system integrated with the microreactor showed a calibration curve in the range of 0.05–1.5 g of ethanol/L, and good results were obtained compared with the ethanol content measured by high-performance liquid chromatography and gas chromatography standard methods.     

Adsorption Equilibrium and Kinetics of Egg-White Proteins on Immobilized Metal Ion Affinity Gels for Designing Fractionation

Designing an Immobilized Metal ion Affinity (IMA) chromatographic process on large scale demands a thorough understanding to be developed regarding the adsorption behaviour of proteins on metal loaded IMA (IMA-M(II)) gels and the characteristic adsorption parameters to be evaluated. This research investigation illustrates the significance of these aspects for the proposed fractionation of chicken egg-white proteins on these gels. Consequently, a systematic investigation of the adsorption characteristics of three chicken egg-white proteins viz., ovalbumin, conalbumin and lysozyme on Cu(II) and Ni(II) loaded IMA gels, iminodiacetate (IDA) and tris(2-aminoethyl)amine (TREN), has been undertaken. These gels differ in their selectivity towards the proteins of interest under the identical sets of experimental conditions. While TREN-Ni(II) was selective only for lysozyme, IDA-Cu(II), IDA-Ni(II) and TREN-Cu(II) showed varying affinities for all the three proteins. The equilibrium and kinetic data were analysed using various theoretical models and adsorption parameters were quantified. On the basis of these investigations, various strategies have been proposed for the efficient large-scale fractionation of chicken egg-white proteins on these gels.     

Determination of phenol and catechol concentrations with oxygen probes coated with immobilized enzymes or immobilized cells

The enzyme phenol 2-hydroxylase was immobilized on Sepharose and used in conjunction with an O₂ electrode for quantitating phenol. Similarly, catechol 1,2-oxygenase was used for quantitating catechol. A third probe was prepared by immobilization ofTrichosporon cutaneum cells rather than purified phenol 2-hydroxylase for phenol quantitation. The whole cell system gave results comparable to the immobilized enzyme system.     

Protection of immobilized sulfhydryl groups against autooxidation by alterations in their microenvironment

Immobilized sulfhydryl groups were prepared by partial thiolation of NH₂-glass beads. The microenvironment of the immobilized SH groups was varied by different chemical modifications of neighboring NH₂ groups. Introduction of a strong charge in the surroundings of immobilized sulfhydryls results in their dramatic stabilization against autooxidation. This effect is due to the salting of O₂ from the surface microlayer of the thiolated beads.     

固载Ru基催化剂上二氧化碳加氢合成甲酸Ⅱ反应条件对催化剂性能的影响

The synthesis of formic acid from carbon dioxide and hydrogen using a silica immobilized ruthenium catalyst as precursor has been studied in different reaction conditions. The results revealed that the TOF （turn over frequency） of HCOOH achieved 1481.5 h^-1 on immobilized ruthenium catalyst near the critical pressure point of CO2 with H2 pressure of 4.0 MPa, reaction temperature of 80℃ and PPh3/Ru molar ratio of 6：1. The reaction activity of immobilized catalyst was higher than that of homogeneous catalyst, and the immobilized catalyst also offered the practical advantages such as easy separation and reuse.     

Preparation and properties of sclerotium rolfsii invertase immobilized on indion 48-R

Crude extracellular invertase fromSclerotium rolfsii, when coupled to glutaraldehyde activated Indion 48-R, retained 70–80% activity of the soluble enzyme. Immobilization resulted in a decrease in the pH and temperature optima but it increased the temperature stability. K_m and V_max also increased as a result of immobilization. Both soluble and immobilized invertase showed inhibition at high substrate concentrations. The bound enzyme showed excellent stability to repeated use and retained approx 90% of its initial activity after 8 cycles of use.     

Axial dispersion in a liquid fluidized bed of particles akin to immobilized enzymes

The axial dispersion of a liquid fluidized bed of controlled pore silica (CPS) particles has been determined by the pulse tracer method. The CPS used was the same as for enzyme immobilization, having an average diameter of 0.436 mm and mean pore size of 37.5 nm. The fluidization liquid is α-amylase liquefied manioc starch, 30% w/v, 45°C pH=4.5. Nominal bed porosities tested were 0.7 and 0.8. The results show that the axial dispersion coefficient increases with greater superficial liquid velocities. Various available correlations tested disagree with each other to a large extent and are unable to represent collected experimental data.     

Tributyl phosphate degradation by immobilized cells of aCitrobacter sp.

Tributyl phosphate (TBP), a plasticizer and solvent, is used in nuclear fuel reprocessing, generating TBP wastes laden with residual uranium. ACitrobacter sp. accumulated heavy metals via a phosphohydrolase(s) that precipitated metals with inorganic phosphate liberated from an organic phosphate “donor” molecule (TBP). Mutant analysis suggested that TBP hydrolysis was not attributable to a previously documented acid phosphatase (monoesterase). Purified monoesterase had little activity against phospho di- and triesters, had no requirement for Mg²⁺ or Mn²⁺, and was EDTA-resistant. Conversely, TBP cleavage by immobilized cells was enhanced by Mg²⁺, and ininhibited by Mn²⁺ and EDTA. A separate phosphotri/diesterase was implicated.     

Preparation and partial characterization of a soluble site-to-site directed enzyme complex composed of alcohol dehydrogenase and lactate dehydrogenase

A soluble, bifunctional enzyme complex has been prepared by crosslinking lactate dehydrogenase and alcohol dehydrogenase with glutaraldehyde. The crosslinking was performed on a solid phase while the active sites of alcohol dehydrogenase and lactate dehydrogenase were held adjacent to one another with the aid of a bis-NAD analog. Subsequently, the enzyme complex was released from the solid phase. The soluble enzyme complex was then purified by using NAD-Sepharose as an affinity adsorbent. Based on gel filtration experiments, the complex was estimated to consist of one of each dehydrogenase. By using a third enzyme, lipoamide dehydrogenase, which competes with lactate dehydrogenase for NADH produced by alcohol dehydrogenase, the effect of site-to-site orientation was studied. It was found that about 83% of the NADH produced by alcohol dehydrogenase was oxidized by site-to-site oriented lactate dehydrogenase compared to a figure of only about 61% obtained in an identical system of separate enzymes. This indicates that given two alternative routes, the preference for the one to lactate dehydrogenase over the one to lipoamide dehydrogenase is enhanced when lactate dehydrogenase and alcohol dehydrogenase are site-to-site oriented.