UNEXPECTED BRANCHING IN PECTIN OBSERVED BY ATOMIC-FORCE MICROSCOPY

Pectic polysaccharides extracted from unripe tomato plant cell walls h ave been imaged with an atomic force microscope (AFM). The images obta ined reveal for the first time a branched structure for tomato pectins that differs from that proposed for the neutral sugar side chains fro m enzymatic hydrolysis and sugar analysis. The branches are between 30 and 170 nm long and are relatively linear. This work demonstrates tha t the AFM is uniquely capable of unambiguously identifying, with minim al sample preparation, individual macromolecules within a heterogeneou s population. (C) 1997 Elsevier Science Ltd.