ISSN:
0006-3525
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
We have measured the thermal melting profile for poly[d(AT)] · poly[d(TA)] as a function of concentration of three trivalent cations: spermidine, me8spermidine, and hexammine cobalt(III). Using McGhee's (1976) theory of DNA melting in the presence of ligands, we have estimated association constants Kh, Kc and binding site sizes nh, nc for binding to double-helical (h) and single-stranded (c) polynucleotide. The results are as follows: TextCationKh (M-1)nh (bp)Kc (M-1)nc (bases)Spermidine9 × 1052.21.3 × 1044.5Me8spermidine2 × 1051.47 × 1033Hexammine cobalt(III)1.1 × 1051.56 × 1026The binding parameters for spermidine and hexammine cobalt(III) to double helical molecules agree fairly well with direct equilibrium dialysis measurements, and are in reasonable accord with predictions of counterion condensation theory. However, despite their identical charges, the three ligands bind to single-stranded DNA with quite different affinities. Estimates of the charge spacing of single-stranded DNA suggest that poly[d(AT)] is less elongated in the presence of spermidine and hexammine cobalt (III) than it is when complexed with me8spermidine.
Additional Material:
12 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/bip.360290105
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