Plant Suspension Culture Media Macromolecules—Pectic Substances, Protein, and Peroxidase

Abstract

Macromolecules secreted into the media by a nondifferentiating suspension culture of tobacco cells were found to be composed of protein and polysaccharide, and to account for the viscosity of the media. The concentration, composition, and viscosity of these macromolecules changed significantly with the age of the culture and growth temperature. The concentration changed from 0.02 mg/ml in newly inoculated cultures to over 1 mg/ml in older cultures. The macromolecules contained from 6 to 18% protein and 3 to 4 mumoles hydroxy-proline/mg nitrogen, more than 20 times the level found in whole cells. The macromolecules contained 5 to 25% pectic substances whose carboxyl groups were either methyl esterified or combined with calcium. Arabinose, xylose, glucose, galactose, and mannose were identified in acid hydrolysates of the macromolecules. Peroxidase activity of the macromolecules increased as cultures became older. Peroxidase isoenzyme patterns changed with culture age and growth temperature. The relation of the macromolecules to cell walls and intercellular substances is discussed.

Calcium-controlled peroxidase secretion by sugarbeet cell suspensions in relation to habituation

“…The release of peroxidases by cell suspensions has been observed in different species [6,7,13,14,15,18,19,201 . Its significance however remains obscure although roles in growth cell cycles [12,13,14], differentiation [211, senescence [13] are postulated for these extracellular enzymes .…”

Changes in proline-14C metabolism in barley seedlings germinating at low temperature

“…The contents of the glass tube were filtered and the filtrates were evaporated to dryness to remove HCl. The amino acid composition of the hydrolysate was analyzed with a liquid chromatograph (19,20). It has been reported that about 95-100% of the protein had repeatedly been recovered by this method (21).…”

Peroxidase Isozymes of First Internodes of Sorghum

“…Peroxidase isozymes of horseradish have molecular weights of approximately 45,000 (9), but higher molecular weight forms have recently been detected in peas (4,8), wheat embryos (11), and Sorghuim seeds (19), and in tissue cultures which secreted complexes associated with hydroxyproline into the medium (14). There is no simple explanation of the stable, multiple peaks of activity of peroxidase in extracts from Sorghum eluted from either Sephadex or Agarose columns, but the causes probably are in common with green leaves since similar peaks are found (23 the isozymes involved all were in the "high molecular weight" group or were slow moving electrophoretic bands.…”