4th EucheMs chemistry congress

Poster Session 1
s1039
chem. Listy 106, s587–s1425 (2012)
Poster session 1 - organic chemistry
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trAnSient And SwitChABLe ProteCtion of
dnA AGAinSt CLeAvAGe By reStriCtion
endonuCLeASeS
P. KieLKowSKi 1 , h. MACíCKová-CAhová 2 ,
M. hoCeK 2
1 Charles University in Prague Faculty of Science, Department
of Organic Chemistry, Prague, Czech Republic
2 Institute of Organic Chemistry and Biochemistry AS CR,
Bioorganic & Medicinal Chemistry, Prague, Czech Republic
The restriction endonucleases type II (REs) are very
important in the manipulation of DNA. [1] In previous studies was
found that several of these showed a high tolerance to the presence
of alkynyl group but not to more bulky groups at position 7 of
7-deazaadenine. [2]
Our method utilises the trialkylsilyl protected 7-ethynyl-7-
-deazaadenine as a bulky substitution of 7-deazaA which protects
the DNA against cleavage by REs and after removal of
trialkylsilyl group the afforded 7-ethynyl-7-deazaadenine is
tolerated by REs and thus, DNA could be cleaved. [3]
.We tested three trialkylsilyl protective groups:
trimethylsilyl, triethylsilyl (TES) and triisopropylsilyl.
According to the experimental results the most suitable protecting
group of 7-ethynyl-7-deazaadenine for our method is TES. The
modified nucleoside triphosphate dAteSetP is very good
substrate for DNA polymerases in primer extension experiment
and the construction of large DNA by PCR. The resulting
modified DNA is fully protected against cleavage by REs.
Another key advantage of using the TES protecting group is the
ease at which it can be removed by the treatment with aqueous
ammonia, which is simply evaporated and without any further
purification DNA could be cleaved by REs.
This approach may find applications in manipulation of
DNA sequences, where target sequences for some REs must be
distinguished.
Acknowledgement: This work is a part of the research
projects Z4 055 0506 supported by the Academy of Sciences
of the Czech Republic. It was specifically supported by Czech
Science Foundation (203/09/0317) and by Gilead Sciences, Inc.
(Foster City, CA, U. S. A.).
references:
1. Pingoud, A.; Jeltsch, A. Nucleic Acids Res. 2001, 29,
3705–3727.
2. Macícková-Cahová, H.; Hocek, M. Nucleic Acids Res.
2009, 37, 7612–7622.
3. Kielkowski, P.; Macícková-Cahová, H.; Pohl, R.; Hocek,
M. Angew. Chem. Int. Ed. 2011, 50, 8727–8730.
Keywords: DNA cleavage; Nucleic acids;
4 th EucheMs chemistry congress
P - 0 3 5 6
Study on the PhySiCAL ProPertieS And
CryStALLizAtion KinetiCS of Modified PP
CoMPoSiteS with nAnofiLLer
y. C. KiM 1 , K. h. yun 1 , P. dAhAL 1
1 Kongju National University, Polymer Science & Engineering,
Cheonan, Republic of Korea
Commercial Polypropylene (PP) exhibits low melt and
impact strengths, which limit its use in foaming and automotive
applications. The melt strength of PP can be improved by
controlling the molecular weight property and introducing
long-chain branches (LCBs). Control of the crystal growth rate is
crucial for the preparation of modified PP (m-PP) with LCB
because the crystallization kinetics affect the polymer processing.
The objective of this study is to determine the effects of LCB
and loading nano-filler on the physical properties and the
crystallization kinetics of m-PP.
M-PPs were prepared by melt grafting and electron beam
irradiation, and m-PP composites with nano-filler were fabricated
by adding 1–7 wt% filler using a mini-compounder at 200 °C.
Layered silicate, carbon nano-tube (CNT), and graphene were
used as the nano filler. There was no difference in the spectra of
m-PP and pure PP whcih were measured by FT-IR and 1H-NMR. To check branch reaction, the branching level was calculated by
zero-shear viscosity and molecular property. The rheological
properties were monitored using an oscillatory viscometer (Anton
Paar, MCR 301). The crystallization behavior of m-PP and the
nanocomposites were analyzed using the isothermal and
non-isothermal kinetic process proposed by Avrami and Ozawa,
respectively. The enhanced melt strength can be interpreted from
the observation that the loading of nano-filler and introducing
LCB into PP enhances its solid-like properties in the PP melts.
The dispersion of nano-filler was verified by transmission electron
microscope (TEM) and X-ray diffraction (XRD). The melt
stregnths of PP were measured by Instron capillary rheometer with
tensiometer.
Keywords: polypropylene; long-chain branch; nano-filler;
nanocomposite; crystallization;
AUGUst 26–30, 2012, PrAGUE, cZEcH rEPUbLIc