insoluble proteins

[gorgio]

insoluble proteins

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Post by gorgio » Sun Dec 10, 2006 7:56 pm

I'm trying to understand some journal articles I'm reading for school and I need help. When people are talking about insoluble protein aggregates, what do they mean by that? Insoluble in what? Can they be made soluble by SDS or other means? If they are insoluble does that mean they can't be run on a Western?

Thanks.

[sdekivit]

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Post by sdekivit » Sun Dec 10, 2006 9:18 pm

insoluble proteins are most of the time transmembrane protein which are apolar and thus not soluble in aqueous solutions and you need to isolate them from the membrane.

[oppox]

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Post by oppox » Mon Dec 11, 2006 9:31 pm

inclusion bodies are insoluble proteins aggregates (not soluble in "water"), the protein forms aggregates when expressed (some proteins have a hydrofobic core but when they arent correctly folded, the core is exposed and can bond through non hydrophobic bonds with other non folded proteins).

This is due to that they are not correctly folded. Membrane proteins as mentioned above (since they are located in a lipid envoirment can cause this problem) but also this can happen when eukaryoutic proteins are expressed in prokaryotics, like E. coli (the caperones cant fold the protein).

The only way except trying to hinder the aggregations from forming is to totally denaturate the protein, yes u can make them soluble by SDS, but the huge disadvantage
is that it loses the properties that the native protein have.

I have never done a western blot, but isnt it a antibody binding to the protein. Can the protein be denaturated?

[zzp1029]

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Post by zzp1029 » Tue Dec 12, 2006 11:18 am

very good! I agree it !

[zzp1029]

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Post by zzp1029 » Tue Dec 12, 2006 11:23 am

i have expressed a protein using Ecoli. frist , i always got protein aggregates. now, i have solved the problem.