tailieunhanh - Nanotechnology Science and Computation Part 11

Tham khảo tài liệu 'nanotechnology science and computation part 11', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 254 B. Samorl G. Zuccheri A. Scipioni P. De Santis vature plots are obtained for each palindromic structure under investigation 18 11 8 . 4 Experimental Evidence of DNA Sequence Recognition by Mica Surface Two Crithidia segments like those in Fig. 3 were ligated either in the tail-to-tail Fig. 4 or in the head-to-head Fig. 5 orientation and two palindromic dimers were constructed. Fig. 4. Pictorial representation of the tail-to-tail DNA palindromic construct. The DNA monomers are composed in a palindromic fashion and sketched as curved ribbons with directionality defined by the sequence. The two opposite DNA faces are indicated with different gray intensities. In b contrary to a the different extent of the local curvature due to the differential interaction of the two monomeric faces with the surface is taken into account. The dyadic symmetry is thus lost and the C-like shape is more correctly expected to be G-like instead. In 3D the dyad axis which characterizes the averaged shape of the palindromic DNA dimers can be oriented along any direction of space with respect to the average plane of the curved tracts. This statistical symmetry constraint also persists when the molecules are flattened on a crystal surface such as mica in SFM images but only two alternative directions of the dyad axis are allowed parallel or perpendicular to the surface plane. In the former case both curved halves of the molecule have the same sign of the curvature sign in the latter case the two curved halves have curvatures opposite in sign. We called these symmetry species C-like shape and S-like shape or S the asterisk indicating the mirror image respectively because the curves are isomorphous with these letters Figs. 4a 5a . The C-like molecules will be characterized by two positive curvatures or two negative ones depending on which end is Hierarchy in the Construction of DNA-Based Nanostructures 255 Fig. 5. Pictorial representation of the head-to-head DNA palindromic construct. See .