[ccp4bb] Dnase activity in E. coli expressed his tag proteins

- Protein crystallography

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- Protein purification
- Crystallisation

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- Programs for crystallography
- X-ray detectors

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CCP4bb <-- 1999 <-- November 1999 <-- 30 November 1999

Previous message:
Subject: Re: Calculating vertical offset of helices
From: Eleanor Dodson ccp4 {- at -} YSBL {- dot -} YORK {- dot -} AC {- dot -} UK
Date: 2007-08-06

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Subject: Bruker Microstar-H with Helios optics and MarDTB
From: praveen kumar praveend22 {- at -} YAHOO {- dot -} COM
Date: 2007-08-06

Subject: Dnase activity in E. coli expressed his tag proteins
From: Narayanan Ramasubbu ramasun1 {- at -} UMDNJ {- dot -} EDU
Date: 2007-08-06

Dear All:
This is off topic but I would rather try here first.
I am wondering whether Dnase could be a contaminant during the nickel
affinity purification of a his.tag protein expressed using pET29b. The
cells were disrupted using sonication only. Very high yield (30 mg/liter
of cell culture). FPLC purification. SDS-PAGE shows a singe band even
when overloaded. Silver staining is in progress.
The protein I am interested in does not have any similarity to Dnase.
However, when treated with supercoiled dna, the dna is degraded as
efficiently as with Dnase I from Sigma.

I am looking for ways to show that my preparation does not have any
Dnase contamination. I would appreciate it very much if someone points
me in the right direction.
Thanks a lot
Subbu

CCP4bb navigation

CCP4bb <-- 1999 <-- November 1999 <-- 30 November 1999

Previous message:
Subject: Re: Calculating vertical offset of helices
From: Eleanor Dodson ccp4 {- at -} YSBL {- dot -} YORK {- dot -} AC {- dot -} UK
Date: 2007-08-06

Next message:
Subject: Bruker Microstar-H with Helios optics and MarDTB
From: praveen kumar praveend22 {- at -} YAHOO {- dot -} COM
Date: 2007-08-06