用电子束辐射法制备固定化乳酸脱氢酶

前言固定化酶的制备,近年来已有许多进展.固定化技术之一的凝胶格子包埋法,尤其受到重视,因为它与其它方法不同,酶分子本身在固定化过程中几乎完全不发生结合或偶联反应,而是被包埋在凝胶的微细格子里.这样,它可能对酶蛋白的构象。

葡萄糖母液缩合反应的原理探索及应用

以葡萄糖母液为原料,在不同葡萄糖母液浓度下,以葡萄糖淀粉酶为催化剂,研究葡萄糖母液糖组成成分的变化情况。结果表明,随着葡萄糖母液干物质浓度的提高,葡萄糖缩合为麦芽糖和异麦芽糖的反应趋势增强。同时,反应物中麦芽糖和异麦芽糖之间的比例也发生变化。反应起始,葡萄糖母液中异麦芽糖和麦芽糖的比例为0.49,异麦芽糖含量为7.16%,60℃下反应72 h后,异麦芽糖与麦芽糖比例为2.67,异麦芽糖含量增加至17.33%。葡萄糖母液经过缩合反应后,其所含的异麦芽糖含量提高了242%。

Macroalage as a source of alpha-glucosidase inhibitors

Alpha-glucosidase inhibitors were screened from organic solvent extracts of macroalgae by a spec- trophotometrical method with p-nitrophenyl-D-glucopyranosidase as the substrate. The result indicates that or- ganic crude extracts from some macroalgae such as Rhodomela confervoides (Huds.) Silva, Gracilaria textorii (Suringar) DeToni, Plocamium telfairiae Harv., Dictyopteris divaricata (Okam.) Okam, Ulval pertusa and En- teromorpha intestinalis (L.) Link et al. show strong inhibitory activity of alpha-glucosidase at concentration of 79.6 μg/ml.

Kinetic Parameter of Alfa-amylase and Glucoamylase Enzymatic Reaction on the Glucose Yield from Hydrolyzed Processes of Tapioca Solid Waste

The increasing of tapioca production nowadays effected the production of waste. The waste of tapioca industries consists of two kinds, which were liquid waste and solid waste. Further more, tapioca solid waste treatment was ineffective. Weather solid waste produced from the extraction process still contains high concentration of starch that can be used to produce high quality product, for example, bio ethanol or other alternative energy sources. Objective of these experimental work was utilizing solid waste of tapioca industries and looking for the exactly composition of n-amylase and gluco-amylase enzymes on the hydrolysis processes of the solid waste of tapioca. The exact composition from both enzymes can be expected to increase the yield of glucose. Variables of cx-amylase enzyme for this research were 0.3% （w/w） and 0.5% （w/w） with liquefaction time were 1 hour and 1.5 hours, and variables of glucoamylase enzyme were 0.3% （w/w） and 0.5% （w/w）. To achieve these goals, the experimental work was held in laboratory scale with batch process. Firstly, tapioca solid waste was pretreated at 90 ~C and added u-amylase enzyme for 1 hour and 1.5 hours （variable of liquefaction time）. Then, substrate was cooled down to 60 ~C added with proposed variables of glucoamylase enzyme, and was analysed 24 hours after added. This experiment showed the best ratio between a-amylase and glucoamylase enzymes 0.5%：0.5% with 1 hour of liquefaction time. The highest glucose reaches 8.468% and yields 0.892 （g glucose/g starch） with starch conversion of 59.94%. KM = 0.0468 g/mL and rmax = 0.311 g/mL·h,

Electrochemiluminescence glucose biosensor based on glucose dehydrogenase functionalized Ru(bpy)_3^(2+) doped silica nanoparticles

A novel electrochemiluminescence (ECL) sensing approach was developed for glucose detection based on crosslinking Ru(bpy)3Cl2-doped silica nanoparticles (RuSiNPs) with glucose dehydrogenase on a glassy carbon electrode (GCE). Glutaral- dehyde and aminopropyltrimethoxysilane were used as linking agents, and chitosan was used to immobilize the composites onto the GCE surface. The ECL sensor presented good characteristics in terms of stability and reproducibility. Under opti- mized conditions, the linear response of ECL intensity to glucose concentration was valid in the range of 0.2 to 20 mmol/L (R2 = 0.9962). The application results indicated that the proposed approach is with great potential in the determination of glucose.

In vitro antioxidant activity and potential inhibitory action against α-glucosidase of polysaccharides from fruit peel of tea(Camellia sinensis L.)

The conditions for extracting polysaccharides from tea （Camellia sinensis L.） fruit peel （TFPPs） were studied. Three parameters （temperature, time, and liquid/solid ratio） affecting the extraction of TFPP were optimized using response surface methodology （RSM）. Under the optimized conditions, the yield of TFPP was predicted to be 4.98%. The physicochemical properties, in vitro antioxidant activities, and inhibitory effects on α-glucosidase of frac- tionated TFPPs （TFPP-0, TFPP-20, TFPP-40, and TFPP-60） were investigated. We found that the TFPPs were all acid protein-bound heteropolysaccharides, although with different chemical compositions. They had not only re- markable scavenging activity on 2,2＇-azinobis（3-ethylbenzothiazoline-6-sulfonic acid） diammonium salt （ABTS） and reducing activity, but also excellent inhibitory potential against α-glucosidase in vitro. Our results suggest that tea fruit peel could be treated as a potential bioresource for the development of polysaccharide antioxidants.

A glucose biosensor based on direct electrochemistry of glucose oxidase immobilized onto platinum nanoparticles modified graphene electrode

The platinum nanoparticles were adsorbed on graphene oxide sheets and played an important role in catalytic reduction of graphene oxide with hydrazine, leading to the formation of graphene-Pt nanoparticles. Because of their good electronic properties, biocompatibility and high surface area, graphene-Pt based composites achieved the direct electron transfer of redox enzyme and maintained their bioactivity well. The graphene-Pt nanocomposites were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM) and selected area electron diffraction (SAED). The amperometric biosensor fabricated by depositing glucose oxidase over Nafion-solubilized graphene-Pt electrode retained its biocatalytic activity and has offered fast and sensitive glucose quantification.