Metal-modified nucleobase pairs and triplets as cytosine receptors.
A preorganized cationic receptor 2 for cytosine (C) is described which is composed of trans-a2PtII (a= NH3 or CH3NH2) cross-linked modules with adenine (A), guanine (G), and uracil (U) or thymine (T) model nucleobases. The functions of these three modules are as follows: i) Adenine orientates the two other bases at right angles, thus producing the L-shape of the receptor. ii) Guanine is the primary receptor. iii) Uracil or thymine act as coreceptors. Compared with the normal Watson-Crick pair between G and C, the association constant between 2 and C increases by a factor of 3 (in DMSO). As deduced from 1H NMR spectroscopy and confirmed by the X-ray crystal structure of the C adduct 4b, cytosine is fixed through five hydrogen bonds to the receptor, one of which involves the aromatic H(5) of C. A comparison of C binding is made with a structurally related linkage isomer receptor as well as the precursor molecule trans[alpha2PtAG]2+. The potential of modular, cationic receptors is illustrated.
Lüth
M S
MS
Fachbereich Chemie der Universität Dortmund, Germany.
Freisinger
E
E
Lippert
B
B
D020029:Base Pairing; D002412:Cations; D018360:Crystallography, X-Ray; D003596:Cytosine / Q000737:chemistry / Q000378:metabolism*; D008024:Ligands; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D010984:Platinum / Q000737:chemistry*; D011687:Purines / Q000737:chemistry; D011743:Pyrimidines / Q000737:chemistry; D011955:Receptors, Drug / Q000737:chemistry / Q000378:metabolism*
D002412:Cations; D008024:Ligands; D011687:Purines; D011743:Pyrimidines; D011955:Receptors, Drug; D010984:Platinum; D003596:Cytosine