Re: [求救] 幾提生化問題

看板Biology (生物學)作者xenosdk (xenosdk)時間17年前 (2008/10/28 00:40)推噓1(1推 0噓 1→)

留言2則, 2人參與討論串1/1

※ 引述《steffanie (Para Paradise)》之銘言： : ※ [本文轉錄自 Biotech 看板] : 作者: steffanie (Para Paradise) 看板: Biotech : 標題: [求救] 幾提生化問題 : 時間: Mon Oct 27 23:56:35 2008 : 1.(a) In gel filtration, larger proteins run faster or slower? Why? : 我知道大的跑比較快但不知道為什麼<囧 Larger proteins does not enter as many pores as smaller proteins. 我相信Wiki有詳細解說 : (b) In SDS-PAGE, larger proteins run faster or slower? Why? : 我知道大的跑比較慢但不知道為什麼<囧 Larger proteins are more heavily charged 同樣詳細答案請查wiki : 2.(1) Can an antibody and its antigen be co-crystallized for X-ray : determination to study the interaction between this antibody : and its antigen? Why? Yes, antigen-antibody complexes have high affinity to one another. Therefore, with a good molar ratio in the crystallization chamber, it is possible to co-crystallize the antibody-antigen complex and study their interaction. : (2) Can we apply the same idea to study the interaction between : an enzyme and its allosteric effector or substrate individually : via co-crystallization? Why? Yes for allosteric effector based on the same rationale. However, substrate co-crystallization is more challenging since enzyme is able to "react" with the substrate and generates a "product". However, we can try overcome this by adding excess amount of substrate, or by introducing a pseudo substrate that binds to the enzyme but will not react with the enzyme. One has to note that by adding excess amount of substrate, it could make the crystallization process even more complex. This may ultimately lower our chance to get a crystal. Also, a pseudo substrate is not the same as a native substrate and it may or may not alter the binding conformation. : 3.(a) Why do we add PITC in the analyses of amino acid composition : and sequencing? : (b) Why do we add 6 M HCl in the analysis of amino acid composition : but not in the analysis of amino acid sequencing? a-b 就是Edman Degradation 整個反應寫出來會很長... 請看Wiki : (c) The existence of disulfide bonds in a protein blocks the Edman : reaction. How to solve this problem during amino acid sequencing? Introduce reducing agents to break the disulfide bonds, i.e. urea. : 請高手指點迷津感激不盡:) 我不是高手有錯請指正 -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 132.216.182.171