Proteolysis and Characterization of Peptidases in Forage Plants

• Published in: Agronomy journal Vol. 98; no. 6; pp. 1392 - 1399
• Main Authors: Pichard, G.R, Tesser, B.R, Vives, C, Solari, C, Hott, A, Larrain, R.E
• Format: Journal Article
• Language: English
• Published: Madison American Society of Agronomy 01.11.2006
• Subjects: Agronomy. Soil science and plant productions; anaerobic conditions; Biological and medical sciences; Economic plant physiology; enzyme activity; Enzymes; forage; forage crops; Fundamental and applied biological sciences. Psychology; genetic variation; Genetics and breeding of economic plants; livestock; molecular weight; Nutrition. Photosynthesis. Respiration. Metabolism; peptidases; protein degradation; proteolysis; proteolytic activity index; rumen fermentation; species differences; temperature; Varietal selection. Specialized plant breeding, plant breeding aims; Yield, quality, earliness, varia; Monocotyledones; Enzyme; Interspecific comparison; Variations; Characterization; Peptidases; Enzymatic activity; Leguminosae; Gramineae; Proteolysis; Dicotyledones; Agronomy; Angiospermae; Hydrolases; Spermatophyta; Fodder crop
• ISSN: 0002-1962; 1435-0645
• DOI: 10.2134/agronj2005.0265

Plant peptidases are involved in protein degradation in the rumen of grazing animals, but little is known about the variation in their activity under anaerobic conditions at 39°C. We investigated the activity of endogenous peptidases in 342 accessions of grass and legume forages and the molecular weight and class of peptidases in a subsample of them. Proteolytic activity was measured by in vitro incubation of tissue over a gelatin substrate. Molecular weight and class of peptidases were assessed by zymograms. A wide range in proteolytic activity index (PAI) was detected (mean PAI = 0.35, ranged from 0.00 to 1.30). More than 88% of the observed variance was due to differences in genus, species, and cultivar. Most of the species had one main peptidase, and their molecular weights ranged from 54 to 130 kDa. In the six species tested, proteases present corresponded to the serine class. The wide variation in proteolysis observed and the predominant occurrence of one peptidase of the same enzyme class support the idea that a reduction of protease activity in forages can be achieved by genetic improvement.