Complexes between Nucleotide Base and Amino Acid. II. Crystal Structure of 5-Bromocytosine : N-Tosyl-l-glutamic Acid

Abstract

The complex crystals of 5-bromocytosine and N-tosyl-l-glutamic acid were obtained from their aqueous solution. The space group is P1 with dimensions of a=10.843(1), b=11.690(2), c=10.879(2) Å, α=122.15(1), β=121.38(1), γ=69.93(1)°, and Z=2. The structure was solved by the heavy atom method and refined by a block-diagonal least-squares method. The undissociated γ-carboxyl group of glutamic acid is bound with O(2) and N(4) of 5-bromocytosine through hydrogen bonds. This interaction mode is different from those found in some cytosine : glycine complexes and cytidine : N-benzyloxycarbonyl-l-glutamic acid complex dihydrate in which the dissociated α-carboxyl group plays a role. This is the first example of interaction between cytosine and the acidic side group of amino acid.

Principles of Nucleic Acid Structure

“…. O 2 (cytosine) (1215,1216). Undissociated carboxyl groups are also observed in thymidine 5'-carboxylic acid where thymine 0 4 and N3-H groups are hydrogen bonded with the carboxyl moiety (1217), and in a nucleoside dipeptide with the terminal carboxyl interacting with adenine NJf and N7 (1218).…”

The hydrogen-bonding network in (+)-N-tosyl-L-glutamic acid

“…Nevertheless, its crystal structure has not been reported to date. The co-crystal of (I) and 5-bromocytosine has been characterized (Ohki et al, 1976). Our previous studies showed that (I) crystallizes as and polymorphs.…”

Intermolecular N–H...O hydrogen-bonding interactions in 5-fluorocytosinium salicylate

“…Cytosine (C) base has been the subject of several investigations aiming to study the relative stabilities of tautomeric forms (Kobayashi, 1998), hydration effects and hydrogen bonding (Sivanesan et al, 2000). The structures of nucleotide complexes, especially cytosine along with amino acids, were extensively studied (Ohki et al, 1974(Ohki et al, , 1975(Ohki et al, , 1976Takenaka et al, 1980). As we have been interested in hydrogen bonding patterns involving aminopyrimidine±carboxylate interactions, we have recently determined the crystal structures of cytosinium hydrogen maleate (Balasubramanian et al, 1996), trimethoprim salicylate monohydrate (Murugesan & Muthiah, 1996), trimethoprim formate (Umadevi & Muthiah, 1994) and trimethoprim maleate (Prabakaran et al, 2001).…”