Latent and Active Polyphenol Oxidase (PPO) in Red Clover (Trifolium pratense) and Use of a Low PPO Mutant To Study the Role of PPO in Proteolysis Reduction

H...............H

Show simple item record

dc.contributor.author Winters, Ana L.
dc.contributor.author Minchin, Frank R.
dc.contributor.author Michaelson-Yeates, Terry P. T.
dc.contributor.author Lee, Michael R. F.
dc.contributor.author Morris, Phillip
dc.date.accessioned 2009-05-26T09:22:25Z
dc.date.available 2009-05-26T09:22:25Z
dc.date.issued 2008-03-25
dc.identifier.citation Winters , A L , Minchin , F R , Michaelson-Yeates , T P T , Lee , M R F & Morris , P 2008 , ' Latent and Active Polyphenol Oxidase (PPO) in Red Clover (Trifolium pratense) and Use of a Low PPO Mutant To Study the Role of PPO in Proteolysis Reduction ' Journal of Agricultural and Food Chemistry , vol 56 , no. 8 , pp. 2817-2824 . en
dc.identifier.issn 1520-5118
dc.identifier.other PURE: 104534
dc.identifier.other dspace: 2160/2389
dc.identifier.uri http://hdl.handle.net/2160/2389
dc.description IMPF: 02.56 RONO: 1920 4063 en
dc.description.abstract Polyphenol oxidase (PPO) activity in leaf extracts of wild type (WT) red clover and a mutant line expressing greatly reduced levels of PPO (LP red clover) has been characterized. Both latent and active forms of PPO were present, with the latent being the predominant form. PPO enzyme and substrate (phaselic acid) levels fluctuated over a growing season and were not correlated. Protease activation of latent PPO was demonstrated; however, the rate was too low to have an immediate effect following extraction. A novel, more rapid PPO activation mechanism by the enzyme’s own substrate was identified. Rates of protein breakdown and amino acid release were significantly higher in LP red clover extracts compared with WT extracts, with 20 versus 6% breakdown of total protein and 1.9 versus 0.4 mg/g FW of free amino acids released over 24 h, respectively. Inclusion of ascorbic acid increased the extent of protein breakdown. Free phenol content decreased during a 24 h incubation of WT red clover extracts, whereas protein-bound phenol increased and high molecular weight protein species were formed. Inhibition of proteolysis occurred during wilting and ensilage of WT compared with LP forage (1.9 vs 5 and 17 vs 21 g/kg of DM free amino acids for 24 h wilted forage and 90 day silage, respectively). This study shows that whereas constitutive red clover PPO occurs predominantly in the latent form, this fraction can contribute to reducing protein breakdown in crude extracts and during ensilage. en
dc.format.extent 8 en
dc.language.iso eng
dc.relation.ispartof Journal of Agricultural and Food Chemistry en
dc.title Latent and Active Polyphenol Oxidase (PPO) in Red Clover (Trifolium pratense) and Use of a Low PPO Mutant To Study the Role of PPO in Proteolysis Reduction en
dc.type Text en
dc.type.publicationtype Article (Journal) en
dc.identifier.doi http://dx.doi.org/10.1021/jf0726177
dc.contributor.institution Institute of Biological, Environmental and Rural Sciences en
dc.description.status Peer reviewed en


Files in this item

Files Size Format View

There are no files associated with this item.

This item appears in the following Collection(s)

Show simple item record

Search Cadair


Advanced Search

Browse

My Account