neo007 Posted April 15, 2006 Share Posted April 15, 2006 Can anyone tell me where the A-form and Z-form of DNA is found? I understand that the B form is found in normal human cells, but where do the other two come from and do/can they exist in human cells? Link to comment Share on other sites More sharing options...
chadn Posted April 15, 2006 Share Posted April 15, 2006 The A-form of DNA exists under conditions of dehydration or high-salt concentrations. The Z-form I believe exists only in the lab. In addition to these three there are also C, D, E, and P forms. All of these....if I am correct are found under laboratory conditions, only. I could be wrong about this, however. Link to comment Share on other sites More sharing options...
neo007 Posted April 15, 2006 Author Share Posted April 15, 2006 so, the B form could potentially "denature" into the A form under high salt concentrations or with dehydration? Link to comment Share on other sites More sharing options...
chadn Posted April 15, 2006 Share Posted April 15, 2006 B-DNA doesnt need to denature to form A-DNA. Link to comment Share on other sites More sharing options...
Yggdrasil Posted April 16, 2006 Share Posted April 16, 2006 The A form of DNA is biologically relevant because it is the conformation taken by double stranded RNAs and DNA-RNA hybrids. Furthermore, some bacteria can convert their DNA from B-DNA to A-DNA when they form spores (Mohr, SC. et al. (1991) PNAS 88, 77-81). Supposedly, the DNA is more resistant to degradation in the A conformation than in the B conformation. Z-DNA is primarily though to be an artifact of the laboratory and there is no evidence that it is biologically relevant. Link to comment Share on other sites More sharing options...
neo007 Posted April 16, 2006 Author Share Posted April 16, 2006 Are there any sites with info about A and Z form DNA in detail? I've tried searching on google, but can't seem to find anything Link to comment Share on other sites More sharing options...
Yggdrasil Posted April 16, 2006 Share Posted April 16, 2006 Wikipedia has some basic information on A and Z DNA (http://en.wikipedia.org/wiki/DNA#A_and_Z_helices_formation), while you can find the crystal structures of A & Z DNA on the PDB (http://www.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/pdb23_3.html) Link to comment Share on other sites More sharing options...
neo007 Posted April 16, 2006 Author Share Posted April 16, 2006 i've come across the wikipedia one before, and yeah is rather basic, but the second link seems more useful and more to what i'm looking for thanks! Link to comment Share on other sites More sharing options...
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