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I would recommend restricted proteolysis, i.e., a time series of digestion
with various proteases. Start with concentration ratios of 1:500
protease:your_protein and check the success by SDS-PAGE. The N-terminus
can be determined by N-terminal sequencing. For the C-terminus you can try
to scale up, run a gel filtration column or (probably better) an ion
exchange column + GF and do a mass spec.

If mass spec does not work (proteins soluble at high salt concentrations
only are a hinderence or if the domains are not well defined by the
proteolysis), you can estimate the weight from SDS-PAGE and make use of
the secondary structure prediction, available e.g. through the
expasyserver (www.expasy.ch).

--
Tim Gruene
Institut fuer anorganische Chemie
Tammannstr. 4
D-37077 Goettingen

GPG Key ID = A46BEE1A


On Mon, 12 Jun 2006, Wang, Yeming (NIH/NIEHS) [F] wrote:

> ***  For details on how to be removed from this list visit the  ***
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>
>
> Sorry for the off-topic question!
>
> My current construct of a new protein (has some homologs) doesn't seem to be 
> good and I have to make some new ones. I am just wondering how to determine 
> the N-terminus & C-terminus of new constructs if I am only interested in 
> structural study of a few domains. Any good methods or softwares to 
> recommend?  Thanks a lot!
>
> Yeming
> ---------------------
> Yeming Wang, Ph.D.
> Laboratory of Structural Biology: Macromolecular Structure Group
> National Institute of Environmental Health Sciences
> National Institute of Health
> Mailing Address:      Street Address:
> NIEHS, MD F3-05       NIEHS, Building 101, Room F362
> P.O. BOX 12233        111 T.W. Alexander Drive
> RTP, NC 27709         RTP, NC 27709
> Tel (o): 919-316-4634
> E-mail: [EMAIL PROTECTED]
>

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