[3dem] Spots in micrographs

[Walsh, Richard Michael]

Hi Saumya,
If these spots are absent in thicker ice; the black spots you are seeing are likely denaturation at the air water interface because of thin ice.

best regards,

Richard M. Walsh , Ph.D.

The Harvard Cryo-EM
Center for Structural Biology

Harvard Medical School
250 Longwood Avenue
SGM 102
Boston MA 02115

Phone: (617) 432-9042
Email:Richard_Walsh at hms.harvard.edu<mailto:Richard_Walsh at hms.harvard.edu>
Web: cryoem.hms.harvard.edu<http://cryoem.hms.harvard.edu/>
________________________________
From: 3dem <3dem-bounces at ncmir.ucsd.edu> on behalf of Bajaj Saumya (Dr) <Saumya.Bajaj at ntu.edu.sg>
Sent: Friday, March 20, 2020 5:49 AM
To: 3dem at ncmir.ucsd.edu <3dem at ncmir.ucsd.edu>
Subject: [3dem] Spots in micrographs


Dear all,



We are trying to solve the structure of a membrane protein. We have recently started seeing black spots (~1nm) on our micrographs (image attached). The pattern is not uniform, as there are areas where there are no spots. We tried changing buffer and detergent stock – that did not help. The grids are commercial graphene oxide girds and our buffer contains 0.03% GDN detergent.



Have any of you noticed something similar, or can help throw some light on what it could be?



Thanks a lot.

Best regards,

Saumya

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