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United States Department of Agriculture

Agricultural Research Service

Title: Biochemical and Chemical Diversity of Pectin Methylesterases: Specific Isoform Identification by Mass Spectrometry

item Savary, Brett
item Nunez, Alberto
item Cameron, Randall

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: June 21, 2005
Publication Date: December 15, 2005
Citation: Savary, B.J., Nunez, A., Cameron, R.G. 2005. Biochemical and chemical diversity of pectin methylesterases: specific isoform identification by mass spectrometry. Abstract. Pacifichem 2005, International Chemical Congress of Pacific Basin. Pectin Chemistry #221.

Technical Abstract: Pectin methylesterases (PMEs) occur as large gene families in higher plants. Multiple isoforms are differentially expressed and accumulated in plant tissues (notably during fruit ripening), modifying pectin structure in cell walls. Individual PMEs vary in biochemical regulation and action on pectin substrates. These properties may be exploited technologically to manipulate pectin fine structure and dependent functional properties. Isoform-specific PME identities are rarely documented by structural characterization in much of the published literature due to the complexity and labor intensity in preparing monocomponent enzymes. We have isolated the multiple PME forms present in Valencia orange fruit to fully document their biochemical and structural properties and to develop them as enzyme tools for specific pectin structure modification. In this report we demonstrate how MALDI-TOF mass spectrometry can be used to match peptide mass fingerprints generated from individual Valencia orange PMEs with theoretical peptide libraries generated from corresponding PME nucleic acid sequence data. The approach is highly sensitive and accurate for detecting both conserved and isoform-specific peptide ion signatures, providing unequivocal identification between structurally similar PME isoforms. This proteomic tool may be applied generally to PMEs, providing a superior means for their identification.

Last Modified: 4/19/2015
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