02285nas a2200205   4500008004100000022001400041245013600055210006900191260008600260300001400346490000700360520147100367653001801838653001001856653001301866653002201879100002501901700002101926856013201947       2008                        eng d  a1525-777000aConformational preferences of hypermodified nucleoside lysidine (k(2)C) occurring at wobble position in anticodon loop of tRNA(IIe)0 aConformational preferences of hypermodified nucleoside lysidine   a325 CHESTNUT ST, SUITE 800, PHILADELPHIA, PA 19106 USAbTAYLOR & FRANCIS INCcJUN  a1158-11740 v273 a<p>Conformational preferences of hypermodified nucleoside, 4-amino-2-(N(6)-lysino)-1-(beta-D-ribofuranosyl) pyrimidinium (Lysidine or 2-lysyl cytidine), usually designated as k(2)C, have been investigated theoretically by the quantum chemical perturbative configuration interaction with localized orbitals (PCILO) method. The zwitterionic, non-zwitterionic, neutral, and tautomeric forms have been studied. Automated geometry optimization using molecular mechanics force field (MMFF), semi-empirical quantum chemical PM3, and ab initio molecular orbital Hartree-Fock SCF quantum mechanical calculations have also been made to compare the salient features. The predicted most stable conformations of zwitterionic, non-zwitterionic, neutral, and tautomeric form are such that in each of these molecules the orientation of lysidine moiety (R) is trans to the N(1) of cytidine. The preferred base orientation is anti (chi = 3 degrees) and the lysine substituent folds back toward the ribose ring. This results in hydrogen bonding between the carboxyl oxygen O(12a) of lysine moiety and the 2'-hydroxyl group of ribose sugar. In all these four forms of lysidine O(12a)...H-C(9) and O(12b)...H-N(11) interactions provide stability to respective stable conformers. Watson-Crick base pairing of lysidine with A is feasible only with the tautomeric form of usual anti oriented lysidine. This can help in recognition of AUA codon besides in avoiding misrecognition of AUG.</p>10ahypermodified10ak(2)C10alysidine10astable conformers1 aSonawane, Kailas, D.1 aTewari, Ravindra  uhttps://library.ncl.res.in/content/conformational-preferences-hypermodified-nucleoside-lysidine-k2c-occurring-wobble-position-0