Solution conformations of valinomycin-divalent cation complexes

Sankaram, M. B. ; Easwaran, K. R. K. (1985) Solution conformations of valinomycin-divalent cation complexes International Journal of Peptide and Protein Research, 25 (6). pp. 585-593. ISSN 0367-8377

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The solution conformations of complexes of valinomycin with magnesium and strontium were investigated by circular dichroism, nuclear magnetic resonance and infrared techniques. The results were compared with our earlier results on lithium, calcium, manganese and barium complexes. All these cations, except lithium, form 2:1 ion sandwich and 1:1 carrier-cation complexes with valinomycin. The 1:1 complex has a conformation different from that of the valinomycin-potassium complex. Lithium forms only the 1:1 complex. Strontium and barium form a large number of 1:2 complexes with open conformations rapidly interconverting in solution in addition to the above 2:1 and 1:1 complexes. These observations are rationalized taking into account the ionic radii and coordination numbers of the cations and the conformational restraints of valinomycin molecules. It is suggested that cations with co-ordination numbers of about six (magnesium and calcium) form the 2:1 and 1:1 complexes whereas those with higher co-ordination numbers (strontium and barium) form 1:2 complexes also.

Item Type:Article
Source:Copyright of this article belongs to John Wiley and Sons, Inc.
Keywords:Carrier Ionophore; Circular Dichroism; Ionophore Conformation; Nuclear Magnetic Resonance; Valinomycin
ID Code:11175
Deposited On:09 Nov 2010 03:52
Last Modified:31 May 2011 09:01

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