Conformations in crystals and solutions of d(CACGTG), d(CCGCGG) and d(GGCGCC) studied by vibrational spectroscopy

Abstract

Crystals of self camplementary DMA hexamers dCCACGTG>, dCCCGCGG> and d<GGCGCC> were grown bf vapour dlffuslon technlque and studled by mlcroRaman and mlcroiR spectroscop es. The ollgonucleotldes were studled ln parallel ln solutlon by vlbratlonal spectroscopy. A B->Z transltlon was detected by Raman spectroscopy cl.lrlng the crystalllzatlon procese for dCCACGTG>. Vlbratlonal spectroscopy shows that the dCGGCGCC> crystals adopt a B geametry. On the contrary the d<CCGCGG> sequence whlch ls shown to be able to undergo ln solutlon or ln fllms qulte easlly the B->Z transltlon, remalns trapped ln crystals ln a geametry whlch may correspond to an lntermedlate conformatlon often proposed ln modele of the B->Z transltlon. The crystals used ln thls study were characterlzed by X-ray dlffractlon. The unlt cell and space group have been determlned.