Millipore's products are easy to use, but it intends to be blocked if you are using raw cell extracts or supernatant of culture media especially you want to collect small MW proteins. I once used a MW cuting 3000's, but I can only concentrate my samples 2-3 times before it was totally blocked.
Basicly, it is a centrifuge tube with a membrane, a little bit like PCR purification kits, except protein is not binding with the membrane. The use of membrane is to separate the residue molecular from the filtrate molecular by molecular weight. You can choose different memberane by the MW cutting (from 3000 to 100000) hence concentrate your target compounds in the sample. It can also be used to desalt and so on.作者: xue258 时间: 2013-4-27 10:40
From the instrument, they didn't say it can be reused. Acturally, I did call the supplier once and they also said it is not suggest to reuse because the membrane will be more or less blocked. And also, you can not wash the membrane very clean to avoid to bring contaminants from last sample. But I personally reused two tubes 4 time and the results are, be honest, quite good. You may remember to soak the tube in ddH2O after use otherwise, the membrane will dry and damaged.作者: jrwyyplt 时间: 2013-4-27 10:41
Well, there are two main categories. One is Amicon Ultra-15 Centrifugal Filter Units, the other is Amicon Ultra-4 Centrifugal Filter Units. 15 means the initial sample volume should be less 15 mL, the 4 means, of course, the initial sample volume should be no more than 4 mL. There maybe some differents between 15 and 4 in price because the larger tube volume, the larger membrane size. So, the 15 one should be a little bit expencive than 4, isn't it? You may want to ask the suppliers how many tubes per pack and also consider whether your centrifuge bucket can hold it (normally it should no problem, but better ask before you buy!). There are 2, 8, 24, and 96 tubes per pack. If you don't know the protein size, suggest you choose the most safe one: Amicon Ultra-4 5K Ultracel-PL memb 2/pk or 8/pk and it could be fixed into 10 mL centrifuge tube.
Good luck.作者: newway 时间: 2013-4-27 10:43
Thank you!what mean is MW cutting from 3000 to 100000,for example, whether MW cutting 3000 means the proteins with MW more than 3000 are concentated and desalted?作者: 131415 时间: 2013-4-27 10:43
That means the membrane cut-off is 3000. There is a formular to convert the cut-off to real molecular weigh. I forgot the formula, but 3000 cut-off is already very small. If I am not wrong, it converts to MW around several hundrads (not accurate here, sorry).
Yeah, you are right. If the MW higher than, (let's use 3000 to represent here), 3000, then it will not go through the membrane but left in the residue part. Small molecules, like sodium Na+, will go through the membrane to the filtrate part. So that, your sample is concentrated and at the same time desalted. If you choose membrane cut-off, let's say, 100000, than some proteins with small MW will also go through the membrane. That means, if you know your target protein's MW, you can choose a suitable membrane to separate the protein you want form others, isn't it? But of course, the shape of a molecule may also effect the filtration efficiency. If a molecule with large MW, theriatically, it will stay in the solution. But, if its shape is rod, than, maybe some of them will also go through the membrane. So, I suggest that you could use the smallest one. I used 3000s one before, almost everything (I mean proteins) stays in the solution.
Are we clear here? Good luck.作者: junhun 时间: 2013-4-27 10:44
amicon ultra－15 cenfilter unitetrifugal units 30元，
在哪里买的？
南京的代理商怎么告诉我要100块一个？
