DNA Clamp (PCNA)

I came across this while researching something else and felt it qualified as a creative act, or maybe facilitator ... of life in general.

The beautiful symmetrical structure pictured below is an integral factor of DNA synthesis.


(Proliferating cell nuclear antigen (PCNA))

Top and side views of a homotrimer of the human PCNA sliding clamp (rainbow colored, N-terminus = blue, C-terminus = red) with double stranded DNA modeled through the central pore (magenta).[1]

Click to expand...

side view, considered toroidal. (check out "toroidal" on wiki if you're not familiar with that term. neat animations, too.)


here's one for E.coli... similar structure.


this one is from the Bacteriophage T4.


From Wikipedia:

A DNA clamp, also known as a sliding clamp, is a protein fold that serves as a processivity-promoting factor in DNA replication.
...
because one of the rate-limiting steps in the DNA synthesis reaction is the association of the polymerase with the DNA template, the presence of the sliding clamp dramatically increases the number of nucleotides that the polymerase can add to the growing strand per association event. The presence of the DNA clamp can increase the rate of DNA synthesis up to 1,000-fold compared with a nonprocessive polymerase.[2]

Click to expand...

Well after i came across those I just had to google for more info and came across this...

Heat maps showing percent deuterium uptake by the PCNA homotrimer 30 and 60 seconds after imersion[sic] in D2O, as determined by HDX-MS.

Click to expand...

http://www.nist.gov/mml/bmd/hdx-ms.cfm


Anyone else thinking of biophotons? (biophotons discussed here: http://cassiopaea.org/forum/index.php/topic,7462.0.html)