发信人: macintosh (麦克老狼), 信区: Biology
标 题: Re: Yeast Enolase_2 Help
发信站: Unknown Space - 未名空间 (Sun Mar 28 13:22:15 2004), 站内信件

If you want to try top-down. You need definitely two things:
1) A proper fragment method for break down large molecule. low energy
CID can handle some small proteins, but I think Enolase is too big
for low energy CID. High energy CID, ECD may help. But the fragmentation
mechanism are quite different from low engergy CID.
2) you need a high accuracy in mass determination. some time, 100ppm
error will give you so many possible matches.

It is not necessary that the weakest bond be broken first in a fragmentation.
In some case, those non-covalent binding can survive and some covalent bond

【 在 mmjjppuu (think+hard) 的大作中提到: 】
: Right. We use CID to fragment whole protein for sequence information and
: protein identification. In terms of complex, you also get a chance to study
: their properties. And more... This is something different from so-called
: "bottom up" stratege and it is called "top-down" method.
: But from our experience, the CID of proteins usually won't give rise to
: another two charge state distribution. We suspect that there is a very weak
: bond present in this protein which led to the exclusive breakage. There is
: some information about the two domains in this protein. However, their masses
: don't match what we saw:-(
: 【 在 macintosh (麦克老狼) 的大作中提到: 】
: : What kind of fragmentation method you used?
: : CID?
: : You fragmented the whole protein? What is the peurpose to fragment the
: : whole protein? Want to get sequence information? or study non-covalent
: : binding?
: a
: of


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