STRUCTURAL TRANSITIONS IN POLYCYTIDYLIC ACID: PROTON BUFFER CAPACITY DATA

ABSTRACT

The pH-dependences of proton buffer capacity of poly(C) were computed on the basis of the literature data. In these curves there were observed four peaks: two narrow and two wide ones. The first narrow peak reflects the process of cooperative formation of double helices, which is induced by protonation of the N3 atom of nucleotide bases. The first wide peak is assigned to noncooperative process of poly(C) double helices protonation at the N3 nitrogen atom. It is proposed that the second wide peak corresponds to noncooperative protonation of the neutral cytosine bases at the oxygen atom. This reaction causes cooperative dissociation of the poly(C) double helices. The second narrow peak reflects the dissociation process.

Keywords:

• Poly(C)
• Proton buffer capacity method
• Protonation mechanism
• Conformation transitions

ACKNOWLEDGMENT

Material of this paper was presented at XIV International Roundtable “Nucleosides, Nucleotides and Their Biological Applications”, 10–14 September, 2000, San Francisco, USA (Abstract 222).