发信人: hooligan (月是故乡明), 信区: Biology
标 题: Re: Yeast Enolase_2 Help
发信站: Unknown Space - 未名空间 (Sun Mar 28 17:18:34 2004), 站内信件

You are right that the CID of proteins usually won't
give rise to anther two charge state distribution.
However, this may be one of the rare cases that you
did observe this phenomenon. In fact, I will predict
that this phenomenon is observed if a protein is
dissociated into two big pieces. As you know, the
charges do not distribute evenly in the protein. When
you fragment it into two big pieces, there ought to
be different charge distributions on these two big
pieces. If you break the protein into one very small
and one very large pieces, you may not observe charge
distributions, due to the much lower possibilities for
different charge distributation on the small fragment.
In fact, this phenomenon is often observed even for
peptide fragmentation. For a 3+ peptide, it is very
commonto observe the y(n)2+ and y(n)+ ions at the same
time. I bet macintosh can confirm this. :)
You experiment sounds interesting, I would like to see
the spectra if possible and maybe I can help you to
interpret them.

【 在 mmjjppuu (think+hard) 的大作中提到: 】
: 标 题: Re: Yeast Enolase_2 Help
: 发信站: Unknown Space - 未名空间 (Sun Mar 28 13:13:33 2004) WWW-POST
:
: 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?
: :
: :
: : 【 在 Allstate (学期折磨中) 的大作中提到: 】
: : : I am working with Enolase_2 from Baker's yeast now. By electrspray, i got
: a
: : : charge state distribution. The fragmentation of each charge states gave me
: : : another two charge states distribution of about half the molecular weight
: of
: : : this protein. The cleavage happens at the backbone between a pair of KK. I
: : : don't quite understand what happend here. If anybody has some idea, please
: : : give me your suggestions! Thank you!
: :
: :
:
:
: --
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