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On the Secondary Structure of Serine-Specific Transfer Ribonucleic Acid.

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121 K . Friedrich, Angew. Chem. 78, 449 (1966); Angew. Chem.
internat. Edit. 5 , 420 (1966).
[3] A . M . Clifford and C . E. Gleim, Amer. Pat. 2391226 IFeb.
25th, 1943; Chem. Abstr. 40, 3136 (1946).
[4] 0. Diels, Chem. Ber. 75, 1452 (1942).
[5] E. L r G o f and R . B. LnCormt, J. org. Chemistry 29, 423
[6] K . Hafner, H. E. A. Kramer, H. Musso, G . Ploss, and G.
Schulz, Chem. Ber. 97, 2066 (1964).
[7] J . H . Day and R. Jenkins, J. org. Chemistry 23, 2038 (1958).
[8] J. C. Wood, R . M . Elofson, and D . M. Saunders, Analytic.
Chem. 30, 1339 (1958).
On the Secondary Structure of Serine-Specific
Transfer Ribonucleic Acid
By H. Doepner, Dr. H. Seidel, and Prof. F. Cramer
Max-Planck-Institut fur Experimentelle Medizin,
Gottingen (Germany)
Recently we described a relation [21 between the thermal
hyperchromicity of variously pre-treated s-RNA's [31 of
different origins and the extent of their base-pairing as determined by N-oxidation.
We have now examined ser-t-RNA from brewer's yeast,
whose nucleotide sequence has been elucidated by Zachau
et aZ.[41. The figure shows the change in absorption on
thermal denaturation of this t-RNA.
Synthesis of Pyrimidine-5-carbaldehyde
By Prof. H. Bredereck, Dr. G. Simchen, Dr. A. Santos, and
H. Wagner
Institut fur Organische Chemie,
Technische Hochschule Stuttgart (Germany)
In the course of our studies on the nucleophilicity of the
5-position of substituted pyrimidines we obtained 4,6-dihydroxypyrimidine-5-carbaldehyde (2)
by reaction in
chloroform a t 0 to 20 "C of 4,6-dihydroxypyrimidine (prepared from malondiamide and formamide) with the reaction
product of dirnethylformamide and phosgene 121. The
formylation was exothermic with a yield of 93 % after 2 to
3 hr.
Chlorination of the quaternary salt ( I ) with phosphorus
oxychloride/dimethylaniline, or of ( I ) in dimethylformamide with phosgene/dimethylaniline (10 hr at 110 "C)
and subsequent removal of the solvent, treatment of the
residue with ice, and extraction with chloroform afforded
4,6-dichloropyrimidine-5-carbaldehyde(3) in 63 % yield [1,31.
The formylation and chlorination can be carried out in one
experiment : after the reaction with the dimethylformamidephosgene product the chloroform is removed and replaced
by dimethylformamide, and phosgene is passed into the
mixture for 10 hr at 110 "C.
Hydrogenation of the chloro-aldehyde (3) with hydrogen
and palladium-charcoal in methanol containing a n excess of
magnesium oxide (to remove the HCI) at room temperature
and pressure and subsequent filtration, distillation of the
methanol, and extraction of the residue with methylene
chloride yielded the new compound pyrimidine-5-carbaldehyde, rn.p. 38-41 "C, in 79 % yield (40 % calculated on
.,L--~-- _ _ I
20 30
LO 50
60 70 80 90 100
Fig. I . Change of extinction at 260 mu ( E m ) on thermal denaturation
of ser-t-RNA in 0.4 M phosphate buffer (pH 7.0) without Mg2+.
The denaturation curve exhibits two steps. The first stage in
the denaturation (between 30 and 45 "C) accounts for only a
small part of the total hyperchromicity (breakdown of
tertiary structure?) [5,61. The second stage may correspond
to destruction of the secondary structure (helix-coil transition).
As seen from the figure, the total hyperchromicity amounts
to 24.5 %, which according to our previous relationship [21
corresponds to about 27 base pairs per molecule of ser-tRNA.The hyperchromicity in the second stage is 18.4%, corresponding [21 to 24 to 25 base pairs per molecule of ser-t-RNA.
This result agrees well with the optimal amount of basepairing attainable by arrangement of the nucleotide sequence
in five helical regions as proposed by Zachau et aZ.[41 for
Received: May 25th. 1966
[Z 249 IE]
German version: Angew. Chem. 78, 682 (1966)
HC%,&- C1
N g YII- C H O
Received: May 25th, 1966
[Z 248 IE]
German version: Angew. Chem. 78, 717 (1966)
[I] A. Santos, Dissertation, Technische Hochschule Stuttgart,
[2] Z . Arnold, Coll. czechoslov. chem. Commun. 24, 4048 (1959).
[3] H . Wagner, Diploma Thesis, Technische Hochschule Stuttgart, 1966.
Angew. Chem. internat. Edit. 1 Vol. 5 (1966) J No. 7
[l] We thank Prof. H . G. Zachau for a sample of ser-t-RNA.
[2] H . Doepner, H . Seidel, and F. Cramrr, Angew. Chem. 78, 601
(1966); Angew. Chem. internat. Edit. 5 , 591 (1966).
[3] The following abbreviations are used: s-RNA = soluble
ribonucleic acid; ser-t-RNA = serine-specific transfer-ribonucleic acid; hyperchromicity = increase in the extinction at 260 mp
on increase in temperature.
[4] H . G . Zachau, D . Diitting, and H. Feldmann, Angew. Chem.
78, 392 (1966); Angew. Chem. internat. Edit. 5, 422 (1966).
[5] P. S. Sarin, P . C . Zamecnik, P. L. Bergquist, and J . F. Scott,
Proc. nat. Acad. Sci. U.S.A. 55, 579 (1966).
[6] D. D . Henley, T. Lindahl, and J . R . Fresco, Proc. nat. Acad.
Sci. U.S.A. 55, 191 (1966).
Synthesis of Oligodeoxynucleotides with Terminal
5'-Phosphate Groups
By Dr. F. Eckstein
Max-Planck-Institut fur Experimentelle Medizin,
Chemische Abteilung, Gottingen (Germany)
Unless enzymatically obtained, all the oligodeoxynucleotides
larger than the dinucleotide synthesized through a dinucleotide intermediate have a hydroxyl group at the 5'-end[ll.
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acid, serine, structure, specific, transfer, secondary, ribonucleic
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