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Three‐way multivariate curve resolution applied to speciation of acid–base and thermal unfolding transitions of an alternating polynucleotide
Author(s) -
Vives M.,
Gargallo R.,
Tauler R.
Publication year - 2001
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/1097-0282(200112)59:7<477::aid-bip1053>3.0.co;2-#
Subject(s) - polynucleotide , chemistry , resolution (logic) , base (topology) , base pair , multivariate statistics , thermal , crystallography , dna , biochemistry , thermodynamics , physics , statistics , mathematical analysis , mathematics , artificial intelligence , computer science
Analytical speciation of acid–base equilibria and thermal unfolding transitions of an alternating random polynucleotide containing cytosine and hypoxanthine, poly(C, I), is studied. The results are compared with those obtained previously for single‐stranded polynucleotides, poly(I) and poly(C), and for the double‐stranded poly(I) · poly(C), to examine the influence of the secondary structure on the acid–base properties of bases. This study is based on monitoring acid–base titrations and thermal unfolding experiments by molecular absorption, CD, and molecular fluorescence spectroscopies. Experimental data were analyzed by a novel chemometric approach based on a recently developed three‐way Multivariate Curve Resolution method, which allowed the simultaneous analysis of data from several spectroscopies. This procedure improves the resolution of the concentration profiles and pure spectra for the species and conformations present in folding–unfolding and acid–base equilibria. The results from acid–base studies showed the existence of only three species in the pH range 2–12 at 37°C and 0.15M ionic strength. No cooperative effects were detected from the resolved concentration profiles, showing that equilibria concerning alternating polynucleotides like poly(C, I) are simpler than those involving poly(I) · poly(C). Thermal unfolding experiments at neutral pH confirmed the existence of two transitions and one intermediate conformation. This intermediate conformation could only be detected and resolved without ambiguities when molecular absorption and CD spectral data were analyzed simultaneously. © 2001 John Wiley & Sons, Inc. Biopolymers 59: 477–488, 2001