1. Department of Biomaterials, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan, Centre de Recherches sur les Macromolécules Végétales−CNRS, affiliated with the Joseph Fourier University of Grenoble, BP 53, 38041 Grenoble Cedex 9, France, and Bioscience Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545