Different nucleobase orientations in two cyclic 2′,3′‐phosphates of purine ribonucleosides: Et3NH(2′,3′‐cAMP) and Et3NH(2′,3′‐cGMP)·H2O |
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Authors: | Katarzyna
lepokura Tadeusz Lis Magorzata Bogucka Joanna Lutomska Adam Kraszewski Krzysztof Sierosawski |
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Abstract: | The crystal structures of triethylammonium adenosine cyclic 2′,3′‐phosphate {systematic name: triethylammonium 4‐(6‐aminopurin‐9‐yl)‐6‐hydroxymethyl‐2‐oxido‐2‐oxoperhydrofurano3,4‐c]1,3,2]dioxaphosphole}, Et3NH(2′,3′‐cAMP) or C6H16N+·C10H11N5O6P?, (I), and guanosine cyclic 2′,3′‐phosphate monohydrate {systematic name: triethylammonium 6‐hydroxymethyl‐2‐oxido‐2‐oxo‐4‐(6‐oxo‐1,6‐dihydropurin‐9‐yl)perhydrofurano3,4‐c]1,3,2]dioxaphosphole monohydrate}, Et3NH(2′,3′‐cGMP)]·H2O or C6H16N+·C10H11N5O7P?·H2O, (II), reveal different nucleobase orientations, viz. anti in (I) and syn in (II). These are stabilized by different inter‐ and intramolecular hydrogen bonds. The structures also exhibit different ribose ring puckering 4E in (I) and 3T2 in (II)] and slightly different 1,3,2‐dioxaphospholane ring conformations, viz. envelope in (I) and puckered in (II). Infinite ribbons of 2′,3′‐cAMP? and helical chains of 2′,3′‐cGMP? ions, both formed by O—H?O, N—H?X and C—H?X (X = O or N) hydrogen‐bond contacts, characterize (I) and (II), respectively. |
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