Effect of pH on the activity of ryegrass Lolium multiflorum proteases

Abstract

The effect of pH on plant protease activity was investigated ysing bufered, gamma-irradiated aqueous extract of ryegrass Lolium multiflorum. Rapid protein breakdown occurred in the first f e w days but was followed by a longer period of reduced activity. The overall pH optimum for ryegrass proteases was between 5.0 and 7.0 but there was still considerable activity at the acid pH levels found, eg in silage. Proteolysis did not proceed to completion even when the pH was not inhibiting.

The effect of cultivar, wilting and storage period on fermentation and the clostridial community of alfalfa silage

“…The formation of NH 3 -N reflects part of the proteolysis occurring during ensiling and is explained by plant enzymatic, clostridial and/or enterobacterial activity (Heinritz et al 2012). Because most plant proteolytic activity occurs within a relatively short period of time followed by a longer period of much reduced activity during ensiling (Heron et al 1989), proteolytic activity of microorganisms might has contributed to the production of NH 3 -N after a longer storage period. When relating the butyric acid data, as an indicator of the clostridial fermentation, to NH 3 -N, NH 3 -N content in direct-cut and 2-h wilted silages could be most likely explained by clostridial activity.…”

Ensiling characteristics, ruminal nutrient degradabilities and whole tract nutrient utilization of berseem clover (Trifolium alexandrinum L.) silage

“…True protein content of BCS declined (P < 0.05) between day 0 and day 2 and between day 2 and day 4 post-ensiling with no further changes after day 4 post-ensiling (Table 1) The increase in SCP and NPN and the reduction in NDICP and true protein between day 0 and day 2 post-ensiling suggest proteolysis of true protein into non-protein compounds during the early stage of ensiling. The degradation of forage protein during ensiling is mediated by plant enzymes collectively known as proteases and results in a reduction in true protein and an increase in NPN contents (Heron et al 1989). Most of the proteolytic activities during ensiling occur within a relatively short period of time followed by a longer period of much reduced activity (Heron et al 1989).…”

“…The degradation of forage protein during ensiling is mediated by plant enzymes collectively known as proteases and results in a reduction in true protein and an increase in NPN contents (Heron et al 1989). Most of the proteolytic activities during ensiling occur within a relatively short period of time followed by a longer period of much reduced activity (Heron et al 1989). It appears that most of the proteolytic activity takes place within the first 2 d post-ensiling, suggesting that proteases of berseem clover forage behave in a similar manner to those found in other forages such as alfalfa, red clover and peas (Papadopoulos and Mekersie 1983;Mustafa et al 2002).…”

Conservation characteristics and protein fractions of cereal silages ensiled with additives at the booting and dough stages of maturity

“…Similar effects of organic acid were also reported by Guo et al (6) in alfalfa silage. Both additives seemed to cause a rapid drop in pH in the silage because plant proteases are more active between pH 6 and 7 than at pH 4 (30). In silages, proteolysis mostly occurs within the first 2 days of ensiling (29,30), and the more rapid the drop in pH, the less extensive the breakdown of protein.…”

“…Both additives seemed to cause a rapid drop in pH in the silage because plant proteases are more active between pH 6 and 7 than at pH 4 (30). In silages, proteolysis mostly occurs within the first 2 days of ensiling (29,30), and the more rapid the drop in pH, the less extensive the breakdown of protein. The reduced proteolysis with the additives resulted in an increase in B1 fraction for all cereal silages.…”