Background
ScarabXpress®-2 system, our second-generation protein expression system, consists of the pSX2 expression plasmid and ANY Clean Genome® E. coli host strain. In side by side comparisons, the ScarabXpress®-2 system protein expression system gave up to 36x higher yields than standard expression vectors with wild-type E. coli strains
Figures
Figure 1. pSX2 Expression Plasmid Map. 
Figure 2. 3000-Fold Induction Range. IPTG Titration of pSX2-GFP, intensity was measured, replicates were averaged and graphed in average fluorescent units. 
Figure 3. ScarabXpress2 Produces ≤ 36x More Protein Than BL21(DE3). 
Figure 4. More Consistent Fermentations With ScarabXpress®-2
Specifications
Kit Components pSX2 Expression Vector, 10 μg Quality Control The vector is confirmed to be IS-free and for functionality. Storage Conditions Store at ≤ -70°C. Do not store in a frost-free freezer.
Related Products
10X Modified Korz Medium Kit White Glove IS Detection Kit MDS™42 Chemically Competent Cell Kit MDS™42 ΔrecA Chemically Competent Cell Kit MDS™42 ΔrecA Blue Chemically Competent Cell Kit MDS™42 Combination Package Chemically Competent Cell Kit ScarabXpress® T7 lac Chemically Competent Cell Kit MDS™42 Electrocompetent Cell Kit MDS™42 ΔrecA Electrocompetent Cell Kit MDS™42 ΔrecA Blue Electrocompetent Cell Kit MDS™42 ΔrecA trfA Electrocompetent Cell Kit MDS™42 ΔrecA trfA Blue Electrocompetent Cell Kit MDS™42 Combination Package Electrocompetent Cell Kit
Support
Product Manuals pSX2 Expression Vector
Patents & Disclaimers
Scarab is providing you with this Material subject to the non-transferable right to use the subject amount of the Material for your research at your academic institution. The Recipient agrees not to sell or otherwise transfer this Material, or anything derived or produced from the Material to a third party. NO RIGHTS ARE PROVIDED TO USE THE MATERIAL OR ANYTHING DERIVED OR PRODUCED FROM THE MATERIAL FOR COMMERCIAL PURPOSES. If the Recipient makes any changes to the chromosome of the Material that results in an invention in breach of this limited license, then Scarab will have a worldwide, exclusive, royalty-free license to such invention whether patentable or not. If the Recipient is not willing to accept the terms of this limited license, Scarab is willing to accept return of this product with a full refund, minus shipping and handling costs. For information on obtaining a license to this Material for purposes other than research, please contact Scarab’s Licensing Department. Scarab Genomics’ technology is covered by U.S. Pat. No. 6,989,265 and related foreign applications. Clean Genome® is a registered trademark of Scarab Genomics, LLC.
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反应体系如下:
plasmid10ul
10xKbuffer5ul
KpnI1ul
BamHI1ul注意千万不可多加总酶量必须<4%
ddH20upto50ul
总体积改变加酶量按比例改变.
你这里应该是单指蛋白质水解酶。事实上，细胞内所有的蛋白水解酶发挥作用都需要一定的条件，并且一般都是有特异性的。有的是序列的特异性，有的是构象的特异性。
大多数的蛋白酶都不会降解自身，因为自身不含蛋白酶的酶切位点。
当然也有特例，最常见的是自身催化酶解。
举个例子，细胞凋亡中起始型的Caspase，例如Caspase-1，在有外界刺激（例如炎症小体存在）的情况下，会自身催化，把自己切割成三个片段，其中的两个片段组合成为四聚体，在下游发挥作用。
其他能够自剪切的酶还有很多，很多酶的成熟都需要外界刺激诱发蛋白酶原的自剪切。例如胰蛋白酶、弗林蛋白酶等。
当然发生这所有的催化反应都是需要特定的条件的。
还有一类就是像胃蛋白酶一类的特异性较差的消化道蛋白酶，其实是可以降解自身的。只是需要在pH很低的情况下，这时候，往往食物来源的蛋白质含量很高，多数蛋白酶用于消化食物，少部分会降解自身（极极少量）。胃持续分泌蛋白酶，因而胃蛋白酶有损失也影响不大。
因为溶蛋白酶是蛋白质本质的酶
（2）不同点：①影响因素：变构调节是由细胞内变构效应剂浓度的改变而影响酶的活性；化学修饰调节是激素等信息分子通过酶的作用而引起共价修饰。②酶分子改变：变构效应剂通过非共价键与酶的调节亚基或调节部位可逆结合，引起酶分子构像改变，常表现为变构酶亚基的聚合或解聚；化学修饰调节是酶蛋白的某些基团在其他酶的催化下发生共价修饰而改变酶活性。③特点及生理意义：变构调节的动力学特征为S型曲线，在反馈调节中可防止产物堆积和能源的浪费；化学修饰调节耗能少，作用快，有放大效应，是经济有效的调节方式。
有谁用碧云天的过氧化氢酶检测试剂盒，在试剂盒的准备工作中，过氧化氢的实际浓度=22.94*A240，我测出来的吸光度是3.3左右，那么乘以22.94就等于76多点，再乘以之前的稀释倍数，大约就是7600mM左右，这样跟说明书中说道的1M相差太多，感觉不对啊，稀释的肯定是没有错的，但是不知道哪里出了错，怀疑说明书就有问题呢，有人做过这个实验吗？能不能准确测出过氧化氢浓度吗？有测过的人帮忙指点一下啊，不知道应该怎么做
胰蛋白酶Trypsin (Parenzyme) 为蛋白酶的一种，EC 3.4.4.4，是从牛、羊、猪的胰脏提取的一种丝氨酸蛋白水解酶。在脊椎动物中，作为消化酶而起作用。在胰脏是作为酶的前体胰蛋白酶原而被合成的。作为胰液的成分而分泌，受肠激酶，或胰蛋白酶的限制分解成为活化胰蛋白酶，是肽链内切酶，它能把多肽链中赖氨酸和精氨酸残基中的羧基侧切断。它不仅起消化酶的作用，而且还能限制分解糜蛋白酶原、羧肽酶原、磷脂酶原等其它酶的前体，起活化作用。是特异性最强的蛋白酶，在决定蛋白质的氨基酸排列中，它成为不可缺少的工具。
