PNAs represent a relatively novel group of nucleic acid analogues in which the backbone of DNA or RNA is replaced by a polyamide backbone to which nucleobases are attached by appropriate linkers [1]1. Nielsen , PE , Egholm , M. , Berg , RH and Buchardt , O. 1991. Science, 254: 1497–1500. [CrossRef], [PubMed], [Web of Science ®], [CSA] View all references. Two main types of PNAs may be singled out [2]2. Falkiewicz , B. 1999. Acta Biochim. Pol., 46: ...