how to make a protein soluble

Marvin Peterson Peterson at
Fri Mar 15 13:57:28 EST 2002

A couple of easy approaches are to induce your protein at low temperatures
(18-20) overnight.  Another way the we use all the time is to put the
construct into a bank of cells and select soluble expression.  There are
significant differences between cell lines.  You can look at DE3 strains of
AD494, BL21, Rosetta, Star, BL21-AI etc, to name a few.

-----Original Message-----
From: ChenHA [mailto:Hzhen at]
Sent: Friday, March 15, 2002 10:24 AM
To: proteins at
Subject: Re: how to make a protein soluble

Su wrote:
> I'm currently working with the pex7 gene in pet 28a vector.
> i ran an sds gel and found that the protein of interest is located in the
> insoluble portion of the cell.. my question is what are some of the ways I
> can make this protein soluble?  Thank you.

It's a matter of luck whether you get soluble protein or not.  As
mentioned by someone else, having a fusion partner sometimes helps with
solubility, the common ones are GST, thioredoxin, maltose-binding
protein (supposed to be best for solubility).  Changing growth condition
also helps - you should aim to reduce to rate of protein expression,
expressing the protein too quickly can result in aggregation of
protein.  Maybe chaperone can help, and if it has a physiological
partner which binds to it, perhaps coexpression with it may also be
useful.  If this protein has binds to any ion or other prosthetic
groups, try adding it to the growth media.

You can also try refolding the protein if necessary, more work perhaps
but sometimes the only solution.  If you are really unlucky, it may not
even refold. 

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