Industrial process proteomics: Alfalfa protein patterns during wet fractionation processing

Abstract

A proteome reference map of major soluble proteins from Medicago sativa (alfalfa) leaves and stems has been established for the first time. Among 195 spots analyzed by mass spectrometry and N-terminal Edman sequencing, 117 spots were unambiguously identified, representing 87 different proteins. Of these 87 proteins, 13 proteins were directly identified from the partial genome of Medicago sativa, 30 from expressed sequenced tags (ESTs) of the model legume Medicago truncatula and 44 from closely relative species by a cross-species protein identification method. The proteome map of Medicago sativa was then set as a reference to study the major high protein content products that are generated during the wet fractionation process of alfalfa green biomass. Using two-dimensional electrophoresis, we studied the variation of the protein patterns at different steps of the industrial-scale process. We clearly show that the process induces significant changes including chemical modifications, proteolytic events, and heat-shock protein responses. Strikingly, a certain level of cellular regulation is conserved during biomass processing, as exemplified by the induction of some heat shock proteins. Finally, all the results obtained in this proteomic study may help to identify novel products and to improve process designs in alfalfa biomass plants.

Characterization of green‐tissue protein extract from alfalfa (Medicago sativa) exploiting a 3‐D technique

“…The couple of spots 39 (14.86 kDa -pI 5.84) and 45 (14.18 kDa -pI 6.45) positively matched the molecular properties of the small subunit of approximately 14 kDa. Different isoforms and degrees of phosphorylation have been reported that shift its pI value appearing as multiple spots with similar M r [30]. The cluster observed in gel images (spots 36 and 42), apparently higher in intensity than the rest of the spots, is a result of the high concentration of Rubisco subunits and its isoforms.…”

Production of green juice with an intensive thermo-mechanical fractionation process. Part II: Effect of processing conditions on the liquid fraction properties

“…Total nitrogen content was determined in crude juice samples by the Kjeldhal procedure [19] with Büchi K-425 and K-350 (Büchi Rungis, France) equipments. Raw juice samples were diluted in deionised water.…”

“…To date, in the wet fractionation plant, the green juice has been only characterised by its protein content determined by its nitrogenous matter according to Kjeldahl analysis (Procedure V18-100; AFNOR, 1985) [19]. Starke et al [2] developed a qualitative and quantitative analysis of carbohydrates in green juices by gas chromatography/mass spectrometry.…”

“…More specific analysis of the green juice was performed by proteomics. Studies of genome products and establishment of proteome maps of alfalfa juice were investigated by Incamps et al [19]. However no specific quantitative method is available in the literature.…”

Changes in inflorescence protein during advanced stages of floret development in Buchloe dactyloides (Poaceae)

“…Moreover, fundamental scientific knowledge of buffalograss still lags far behind that of other plants, e.g., maize, alfalfa, wheat, and rice (Imin et al, 2001;Andon et al, 2002;Campo et al, 2004;Incamps et al, 2005). Therefore, the objective of this study was to utilize a proteomic approach (isoelectric focusing/sodium dodecyl sulfate-polyacrylamide gel electrophoresis [IEF/SDS-PAGE] and matrix-assisted laser-desorption time-of-flight [MALDI-TOF/TOF]) to evaluate changes in protein expressions during the sex determination stages of buffalograss floret development.…”