Changes in the distribution of nitrogen and plant enzymatic activity during ensilage of lucerne treated with different additives     

X. Guo  H. Zhou  Z. Yu  Y. Zhang 《Grass and Forage Science》2007,62(1):35-43

Effects of formic acid, formaldehyde and two levels of tannic acid on changes in the distribution of nitrogen (N) and plant enzymatic activity during ensilage of lucerne (Medicago sativa) were studied. Lucerne [300 g dry matter (DM) kg^?1 forage] silages were prepared untreated (control) and with formic acid (4 g kg^?1 DM), formaldehyde (1 g kg^?1 DM) and two levels of tannic acid (20 and 50 g kg^?1 DM) as additives. Inhibition of proteolysis by formic acid was more effective than the other additives during the first 7 d of ensiling. Tannic acid was as effective at inhibiting production of non‐protein‐N, ammonia‐N and free amino acid‐N as formic acid and formaldehyde. However, increased concentrations of non‐protein‐N and free amino acid‐N in silage from day 1 to 35 of ensiling were less with the higher level of tannic acid than that in the control and other additive‐treated silages. Carboxypeptidase lost its activity slowly with increasing time of ensiling. At day 2, it still had 0·79 of the original activity in the control silage. After 21 d of ensiling, high levels of carboxypeptidase activity, proportionately 0·41, 0·49, 0·10, 0·35 and 0·30 of the original activity, remained in the control silage, and silages made with formic acid, formaldehyde, and low and high levels of tannic acid respectively. There were higher levels of activity of acid proteinase in formic acid‐treated silage than in the control silage until day 2 of ensilage indicating that the reduction of proteolysis by formic acid was probably due to acidifying the forage below the pH optima of plant protease. Aminopeptidase activity in all silages declined rapidly after ensiling.  相似文献   

中性蛋白酶分步酶解花生分离蛋白制备花生短肽的研究     

李宁  刘红芝  刘丽  王强 《中国农业科学》2013,46(24):5237-5247

【目的】为了充分利用花生榨油之后的副产物,提高产品附加值,建立花生短肽制备工艺,研发功能性花生短肽产品。【方法】通过比较酶种类、底物浓度、酶解温度、酶解时间对水解度与短肽得率的影响,采用二次回归正交旋转组合设计优化分步酶解制备花生短肽的最佳工艺。【结果】中性蛋白酶分步酶解花生分离蛋白制备短肽的最佳工艺参数为：Neutrase水解花生分离蛋白2.04 h后加入Protamex继续酶解1.96 h,Neutrase添加量为5 200 U•g-1底物,Protamex添加量为422.32 U•g-1 底物,水解温度44.83℃,底物浓度8%,在此条件下,短肽得率为83.93%,水解度为38.25%,花生短肽纯度为93.85%±0.44%。经高效液相色谱测定,分子量小于1 000 D的水解产物占98.88%。【结论】采用Neutrase与Protamex分步酶解花生分离蛋白制备花生短肽,与现有碱性蛋白酶酶解制备花生短肽方法相比,避免了后续脱盐步骤,简化了工艺,且具有制备条件温和,DH和TCA-NSI高,纯度高,分子量集中分布于1 000 D以下等特点。  相似文献   

不同水产复合酶对芙蓉鲫的应用效果研究     

翁晓辉  徐树德  王敏  杜红方  史宝军 《饲料与畜牧》2013,(10):18-20

试验芙蓉鲫;500尾随机分成4个组,每组5个重复．每个重复放养25尾鱼。对照组为不添加复合酶制剂的基础日粮,试验组在基础日粮下添加不同公,--j水产复合酶微丸,添加量为200g／t,养殖时间为8周。结果表明：添加水产复合酶的生长性能、对肝脏蛋白酶和淀粉酶都比对照组的高。添加了溢多利公司水产复合酶试验组的终末尾均重和增重率比对照组提高5．12％、12．09％,饵料系数降低了7．14％且差异显著（P〈0．05）,肥满度提高7．55％,差异不显著（P〉0．05）;溢多利水产复合酶对淀粉酶活性提高,分别较公司1复合酶、对照组、公司2的复合酶三组提高1．29％、3．49％、4．73％;蛋白酶的活性提高6．46％、1．77％、0．44％。由此可见,添加200g／t的溢多利水产复合酶对芙蓉鲫的生长性能和内源酶活性提高的效果是最好的。  相似文献   

梅花鹿朊蛋白核心片段的基因克隆与高效表达   总被引：1，自引：1，他引：0  

刘东  卢士英  李岩松  李兆辉  王光明  张媛媛  周玉  宋杰  柳增善  任洪林 《中国畜牧兽医》2012,39(3):78-80

本试验根据梅花鹿朊蛋白基因序列设计引物,利用PCR的方法从梅花鹿基因组DNA中扩增朊病毒蛋白酶抵抗区域PrP^res,将该片段分别与表达载体pET-Trx和pET-His连接,构建重组表达载体pET-Trx-PrP^res和pET-His-PrP^res。分别将两个重组表达载体转入E.coli BL21(DE3) plys宿主菌中,37 ℃诱导4 h,经SDS-PAGE分析,Trx-PrP^res和His-PrP^res表达量分别为38.2%和30.1%。  相似文献   

风味蛋白酶提升烟叶抽吸品质的研究     

肖明礼  杨庆  林锐峰  普元柱  包秀萍  李仙 《浙江农业学报》2014,26(1):0

为了提升上部烟叶的抽吸品质,采用风味蛋白酶处理降低烟叶中蛋白质含量,并分析了风味蛋白酶处理后烟叶的物理结构、游离氨基酸及香气物质的变化情况。烟叶经风味蛋白酶处理后,质地变疏松;蛋白质含量降低,最大降幅达191%;香气质改善,杂气减轻,刺激减小,余味干净,苦味和辛辣味明显减弱;游离氨基酸和香气物质含量增加。上述结果表明,风味蛋白酶处理可以从多方面提升烟叶抽吸品质。  相似文献   

豇豆胰蛋白酶抑制剂基因(CpTI)的克隆及其植物表达载体的构建   总被引：2，自引：2，他引：0  

罗娟  王秀敏  韩烈保  刘君  曾会明  吴云锋 《西北农业学报》2008,17(3):16-19

用CTAB法提取豇豆叶片总DNA后,根据基因两端的保守序列设计引物,经PCR方法扩增得到CpTI基因,将其克隆到pMD-18T载体上,酶切并测序鉴定,将该基因登陆到GeneBank(NO.EU088405)并进行同源性鉴定,证明该基因为丝氨酸蛋白酶抑制剂基因家族中的一员。在此基础上,将CpTI基因用限制性内切酶BamHⅠ/SacⅠ切下后,克隆到pCUbi1303的UBI启动子和NOS终止子之间。经PCR和酶切鉴定,得到了该基因的真核表达载体pCUbiCpTI1303,为下一步的转基因做好了准备。  相似文献   

Preparation and Identification of Hyaluronic Acid From Fresh Pigskin   总被引：1，自引：0，他引：1  

ZHAO Yuhong  HAN Linlin 《东北农业大学学报(英文版)》2008,15(3):44-49

Hyaluronic acid （HA） had been prepared from pigskin residues with neutral proteinase. The preparing results and conditions were studied. After extracting and purification, HA was detected through ultraviolet spectra and infraction spectrum, and its content and purity were tested by carbazole and Elason-Morgan, respectively. This results indicated that significant quantities of HA could be prepared in fresh pigskin with biologic enzyme, and the pure HA was cosmetic grade and food grade.  相似文献   

Potato cultivar Etola exhibits hypersensitive resistance to PVYNTN and partial resistance to PVYZ‐NTN and PVYN‐Wi strains and strain‐specific alterations of certain host miRNAs might correlate with symptom severity          下载免费PDF全文

Z. Yin  F. Xie  K. Michalak  M. Pawełkowicz  B. Zhang  Z. Murawska  R. Lebecka  E. Zimnoch‐Guzowska 《Plant pathology》2017,66(4):539-550

  相似文献   

Bio-potency of serine proteinase inhibitors from Acacia senegal seeds on digestive proteinases, larval growth and development of Helicoverpa armigera (Hübner)     

S. Ramesh Babu  B. Subrahmanyam 《Pesticide biochemistry and physiology》2010,98(3):349-358

Proteinase inhibitors (AsPIs) with high activity against serine proteinases were purified from seeds of the tree legume, Acacia senegal by ammonium sulfate precipitation followed by DEAE-Sephadex A-25 column and evaluated against Helicoverpa armigera larvae by in vitro and in vivo methods. The molecular weight of AsPIs was found to be approximately 19.58 ± 1.00 and 21.23 ± 1.00 kDa for PI and 18.16 ± 1.00 kDa for PII on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The AsPIs (5 μg/ml) inhibited approximately 70% of midgut trypsin and 61% of elastase-like chymotrypsin. In vitro studies showed that AsPIs have remarkable inhibitory activity towards total gut proteolytic enzymes followed by trypsin and chymotrypsin. The IC₅₀ of AsPIs for midgut trypsin was 0.1 μg/ml and for chymotrypsin was 2.0 μg/ml. The inhibition of gut proteinase enzymes was of the non-competitive type. In larval feeding studies, AsPIs were found to retard growth and development of H. armigera and also affects the fecundity of the pest. The results advocate the use of AsPIs in transgenic technology to develop plant resistance to H. armigera.  相似文献   

番茄受伤反应防御信号的遗传解析     

刘丽艳  李传友  李柱刚  李希臣  李铁  马凤鸣 《东北农业大学学报》2005,36(1):23-27

番茄植株受伤诱导的蛋白酶抑制剂(PIs)为研究诱导抗性提供了模型体系,该模型体系可以说明调控系统防御反应信号传导的各种途径。在细胞间,受伤诱导PIs表达的是多肽系统素和氧脂衍生的植物激素茉莉酸,系统素和茉莉酸在同一信号途径中协同作用激活了PIs和其他相关防御基因的表达。  相似文献