| 查看: 269 | 回复: 0 | ||
[求助]
【求助】+有关酶与底物的问题
|
|
会做一部分但是不确定呀。第1问不明白，3不确定用什么方法。第一问主要讲：为什么这个酶在它的基底附近的区域显示出氨基酸的高保守度（和这个酶family的）？下面是原题，其实很好懂的，就是需要些耐心，麻烦大家了！给些重要提示就行呢，完全没有思路呀。。。就告诉我第一问也行呀，拜托了，好郁闷。。。 Examine the crystal structure in figure 1 below of the enzyme, Alpha, an essential enzyme of DNA metabolism from a human parasite. This enzyme is found in all eukaryotic genomes that have been sequenced. The residues in the structure are shown with their electron density to give an indication of the true 3-dimensional shape of the protein. The residues are coloured according to their degree of conservation within the eukaryotic Alpha-protein family. Absolutely conserved amino acids shared by all Alpha-like enzymes are coloured in the darkest shade of grey. Amino acids, with lesser degrees of conservation, are indicated by lighter grey shading, whereas those amino acids with no homology are coloured white. The position of the bound substrate for enzyme Alpha is indicated. (a) Explain, with reference to the above figure why the area around the substrate shows the greatest degree of amino acid conservation within the Alpha enzyme family ================= Further structural analysis of enzyme Alpha reveals a binding site for the drug that is known to selectively target the parasite enzyme, see figure 2 below. Intriguingly neither enzymes Beta (human) or Gamma (mouse) are affected by the inhibitor molecule that is found to bind to enzyme Alpha (parasite), despite considerable sequence homology in this region of the three proteins. It appears that the inhibitor does not bind to these enzymes. The company developing the inhibitor for use against the parasite are unable to crystallise the human or mouse enzymes to understand the basis for the selective inhibition of the parasite enzyme. You are asked by the company developing the inhibitor to deduce the likely basis for the selective binding to the parasite enzyme. You decide to align the eleven amino acid region where the enzyme Alpha binds the inhibitor molecule with the same regions of enzymes Beta and Gamma, shown in figure 3, below. 1 5 10 Enzyme Alpha (parasite) SGDLVRGKEGR Enzyme Beta (human) TYNVIRGDNYR Enzyme Gamma (mouse) TGDIVRGENFR Figure 3. Amino acid alignment of the parasite drug binding site Alignment of homologous region to parasite drug binding site in the human and mouse proteins, numbering is for the parasite sequence arbitrarily beginning at residue 1. (b) Suggest, with reasons, which amino acids may be involved in binding the inhibitor and thus explain why enzymes Beta and Gamma do not bind the inhibitor molecule. (c) Write a brief outline of how you would assay the role of the residues in Alpha or Beta to confirm your hypothesis about which residues are responsible for inhibitor binding. You may assume that a simple, quantitative in vitro assay is available to monitor enzyme activity, that all three enzymes are cloned into expression plasmids and that soluble forms of the proteins can be prepared easily from the bacterium E.coli. (d) The human homologue of the parasite protein functions as a monomer of 48 kDa. It also exists as a tetramer whose role is not known but appears to be functionally inactive. It does not seem to be post-translationally modified when isolated from human tissue. On incubation of the tetramer with magnesium it dissociates into the metal-dependent active form. Outline how would prepare a sample of the protein for crystal trials. You may take advantage of whatever technology you are familiar with.   |
回复此楼» 猜你喜欢
材料复试求调剂
已经有8人回复
-
一志愿0703化学招61最终排名62化学求调剂
已经有17人回复
-
考研调剂
已经有5人回复
-
085600材料与化工301分求调剂院校
已经有33人回复
-
284求调剂
已经有9人回复
-
269求调剂
已经有5人回复
-
285求调剂
已经有6人回复
-
283求调剂
已经有17人回复
-
292求调剂
已经有8人回复
-
070300化学 求调剂
已经有11人回复
找到一些相关的精华帖子，希望有用哦~
酶解多少g底物对应多少酶活力是什么意思？
已经有9人回复
- 如何定位酶与底物的作用位点
已经有6人回复
- 影响酶切的几个主要因素
已经有13人回复
- 关于蛋白重组表达的问题
已经有6人回复
- 【求助/交流】请教：酶液对底物的转化问题
已经有8人回复
- 【求助/交流】淀粉酶吸附
已经有17人回复
- 【求助/交流】固定化酶的底物量如何确定
已经有8人回复
- 【求助/交流】关于酶的底物筛选方法
已经有8人回复
- 如何求酶促反应中最大反应速度？单位是什么？
已经有9人回复
- 【求助/交流】关于HRP的使用问题
已经有7人回复
- 以NADH为底物的酶的酶活测定
已经有10人回复
点击这里搜索更多相关资源科研从小木虫开始，人人为我，我为人人
