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Report Summarizes Nuclear Magnetic Resonance Study Findings from Arizona State University (Reversible assembly of ?-sheet nanocrystals within...

July 4, 2014

Report Summarizes Nuclear Magnetic Resonance Study Findings from Arizona State University (Reversible assembly of ?-sheet nanocrystals within caddisfly silk)

By a News Reporter-Staff News Editor at Health & Medicine Week -- Fresh data on Nuclear Magnetic Resonance are presented in a new report. According to news reporting originating in Tempe, Arizona, by NewsRx journalists, research stated, "Nuclear magnetic resonance (NMR) and X-ray diffraction (XRD) experiments reveal the structural importance of divalent cation-phosphate complexes in the formation of ?-sheet nanocrystals from phosphorylated serine-rich regions within aquatic silk from caddisfly larvae of the species Hesperophyla consimilis. Wide angle XRD data on native caddisfly silk show that the silk contains a significant crystalline component with a repetitive orthorhombic unit cell aligned along the fiber axis with dimensions of 5.9 A x 23.2 A x 17.3 A."

The news reporters obtained a quote from the research from Arizona State University, "These nanocrystalline domains depend on multivalent cations, which can be removed through chelation with ethylenediaminetetraacetic acid (EDTA). A comparison of wide angle X-ray diffraction data before and after EDTA treatment reveals that the integrated peak area of reflections corresponding to the nanocrystalline regions decreases by 15-25% while that of the amorphous background reflections increases by 20%, indicating a partial loss of crystallinity. (31)P solid-state NMR data on native caddisfly silk also show that the phosphorylated serine-rich motifs transform from a rigid environment to one that is highly mobile and water-solvated after treatment with EDTA. The removal of divalent cations through exchange and chelation has therefore caused a collapse of the ?-sheet structure. However, NMR results show that the rigid phosphorus environment is mostly recovered after the silk is re-treated with calcium. The (31)P spin-lattice (T1) relaxation times were measured at 7.6 3.1 and 1 0.5 s for this calcium-recovered sample and the native silk sample, respectively."

According to the news reporters, the research concluded: "The shorter (31)P T1 relaxation times measured for the native silk sample are attributed to the presence of paramagnetic iron that is stripped away during EDTA chelation treatment and replaced with diamagnetic calcium."

For more information on this research see: Reversible assembly of ?-sheet nanocrystals within caddisfly silk. Biomacromolecules, 2014;15(4):1269-75. (American Chemical Society -; Biomacromolecules -

Our news correspondents report that additional information may be obtained by contacting J.B. Addison, Dept. of Chemistry and Biochemistry, Arizona State University , Tempe, Arizona 85287-1604, United States. Additional authors for this research include W.S. Weber, Q. Mou, N.N. Ashton, R.J. Stewart, G.P. Holland and J.L Yarger (see also Nuclear Magnetic Resonance).

Keywords for this news article include: Tempe, Arizona, United States, North and Central America, Nuclear Magnetic Resonance.

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Source: Health & Medicine Week

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