Neutron diffraction and proton nuclear magnetic resonance: complementary probes of in situ cellulose dimensions and primary plant cell wall structure

Abstract

Neutron diffraction was used to monitor the microscopic structure of cell walls from etiolated bean (Phaseolus vulgaris L.) hypocotyls after successive chemical fractionations with ammonium oxalate – oxalic acid and potassium hydroxide. Wide angle neutron scattering measurements showed that there was no highly ordered long range structure and confirm results from proton nuclear magnetic resonance techniques that there is alteration of the cell wall cellulose by chemical fractionations. Small angle scattering measurements showed that the residual cellulose microfibrils increased in diameter from 75.0 ± 2.3 to 110.0 ± 4.2 Å (1 Å = 0.1 nm) after successive treatments with ammonium oxalate – oxalic acid and potassium hydroxide. The technique has potential applications to study cellulose dimensions in situ. Key words: plant cell wall, cellulose dimensions, neutron diffraction, proton NMR.