Presentation day

wednesday  1:00 PM

 

TITLE

Small angle X-ray scattering from polypod-shaped DNAs and their activity of cytokine secretion

Abstract

We explored the relation between detailed structure in aqueous solution and the cytokine
secretion of four polypod-shaped DNAs, called polypodnas. The polypodnas were made with 3-6 DNA
chains and a half of a chain had complemental sequence of another half of chain, and the two half chains
bound each other and the 3-6 chains formed 3-6 “pods” respectively. We named them as tri-, tetra-, penta-,
and hexapodna.
We carried out the cytokine secretion measurement, and we found that with increase of the pod numbers,
the amounts of the secretion drastically increased, especially the amounts of the pentapodna and
hexapodna were four times or much larger than tripodna and tetrapodna.
Using synchrotron X-ray scattering, we tried to reveal the detailed structure of the polypodnas, and we
found following three insights. (1) The gyration radii of the polypodnas increased with increase of their pod
numbers. (2) The arms of the all polypod DNA included B-type DNA. (3) Some bases of the pentapodna
and the hexapodna did not make hydrogen bonds and there were some single chain regions at the center
of the each polypodna, in spite of that tripodna and tetrapodna made fully matched double helices. We
think this “loosened center” is due to the increase of the steric hindrance and electric repulsion with the
increase of the arm number.
Their loosened centers in the polypod DNAs accelerated their cytokine secretion because their loosened
structures had advantages to expose of their bioactive sequences.