An extracellular macromolecular complex from the surface of soybean suspension cultures.

A cell-free, insoluble cell wall fraction is described which floats on the surface of suspension cultures of Glycine max L. Merrill var. Acme cells. Its accumulation is governed by both the shaking speed and the medium volume, a shaking speed of 110 to 120 revolutions per minute with a medium volume of about 100 to 120 milliliters in a 250-milliliter flask being optimal. Various factors which could control the accumulation of the complex were tested and are discussed, and scanning electron micrographs of the complex being released from the cell surface are presented.The composition of the complex by weight is 46% galacturonic acid, 36% protein, 11% lignin (apparent), 4.4% arabinose, 2% ash, and 0.5% methyl ester. Evidence for an intimate relationship between the uronic acid and protein fractions is presented. The protein contains hydroxyproline, and the bulk of it is tightly bound to the complex, although a portion can be removed with high salt treatments.