Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: December 12, 2004
Publication Date: January 12, 2005
Citation: Savary, B.J., Nunez, A., Cameron, R.G. Mass spectroscopy profiling of tryptic-peptides for identifying pectin methylesterases isolated from valencia orange [(citrus sinensis (l.) osbeck] fruit. Abstract 229TH NATIONAL MEETING, AMERICAN CHEMICAL SOCIETY, SAN DIEGO, CA., March 13-17, 2005. Cell 118. Technical Abstract: The multiple forms of pectin methylesterase (PME) present in citrus fruit tissues vary in action on juice cloud-associated pectin substrates and subsequently their impact on juice cloud stability and product quality. Variance in action on pectin may represent differences in mechanism of action by PME isoforms. These differences may be exploited for manipulating patterns of unestersterified galacturonic acids to tailor charge density and distribution in pectin. PME specific identities are rarely documented by structural characterization due to the complexity and labor intensity in preparing monocomponent enzymes. In this report we applied MALDI-TOF mass spectrometry to match peptide mass fingerprints generated from individual PMEs isolated from Valencia orange fruit tissue with theoretical peptide libraries prepared 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. Our results presented here indicate the thermally tolerant PME isoenzyme is structurally related to the family of polygalacturonase-inhibitor proteins.