Disodium guanosine 5'-monophosphate self-associates into nanoscale cylinders at pH 8: a combined diffusion NMR spectroscopy and dynamic light scattering study

Alan Wong (Author), Ida Ramsey (Author), Lea Spindler (Author), Gang Wu (Author)

Abstract

We report a combined NMR and dynamic light scattering (DLS) study on the size of supramolecular structures formed by disodium guanosine 5'-monophosphate, Na2(5'-GMP), at pH 8. In general, two distinct types of aggregate species are present in an aqueous solution of Na2(5'-GMP). One type consists of stacking 5'-GMP monomers, and the other contains stacking G-quartets. Both types of aggregates can be modeled as rodlike cylinders. The cylinder diameter is 10 and 26 A for monomer aggregates and quartet aggregates, respectively. For Na2(5'-GMP) concentrations between 18 and 34 wt %, the cylinders formed by stacking G-quartets have an average length between 8 and 30 nm, corresponding to a stack of ~24-87 G-quartets. These nanoscale aggregates are significantly larger than what had previously been believed for Na2(5'-GMP) self-associationat pH 8. The length of both types of 5'-GMP aggregates was found to increase with Na2(5ć-GMP) concentration but was insensitive to the added NaCl in solution. While the aggregate size for monomer aggregates increases with a decrease in temperature, the size of G-quartet aggregates is essentially independent of temperature. We found that the size of G-quartet aggregates is slightly larger in D2O than in H2O, whereas the size of monomer aggregates remains the same in D2O and in H2O. We observed a linear relationship between the axial ratio of the 5ć-GMP cylinders and the Na2(5'-GMP) concentration for both types of 5ć-GMP aggregates, which suggests a common stacking mechanism for monomers and G-quartets.

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Data

Language:	English
Year of publishing:	2005
Typology:	1.01 - Original Scientific Article
Organization:	UM FS - Faculty of Mechanical Engineering
UDC:	539:544
COBISS:	9783574
ISSN:	0002-7863
Views:	993
Downloads:	78
Average score:	0 (0 votes)
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Other data

Secondary language:	English
URN:	URN:SI:UM:
Pages:	str. 6990-6998
Volume:	ǂVol. ǂ127
Issue:	ǂno. ǂ19
Chronology:	2005
ID:	8718315