※ 引述《[email protected] (因為有妳所以精彩)》之銘言： : 雖然以前曾經懂過，現在又全都忘光了， : 就是在做SDS-PAGE時，Stacking gel的目的是讓sample全在一個起跑點， : 好像跟當時的pH以及glycine有關， : 但是細節有點忘了， The outline of the answer is given here. The pH of stacking gel is about 6.7 (or 6.8?) whereas the pH of the running gel (or separation gel) is about 8.9 (or 8.8). At pH 6.7, the net charge of Gly is close to zero, so the mobility of Gly is very low. Because of this, the 20-25 ul of protein sample can be compressed into a very thin layer in the stacking gel. Also, the percentage of acrylamide in the stacking gel is very low (compared with in separation gel ), so very little molecular sieving occurs here. Thus, proteins of different molecular weights are not separated in the stacking gel, and are condensed to a thin layer. -- "...What science has accomplished is to tell us that this happens because organisms contain genes in them and that the future organism is written in this 'somehow'. And 'somehow' is what we have to explain. We have to say not 'somehow', but 'how'. " Syndney Brenner -- ※ Origin: 臺大電機 Maxwell 站 ◆ From: pool-151-197-112-37.phil.east.verizon.n