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Gluten Proteins in Relation to Celiac Disease. Donald D. Kasarda, Ph.D. Research Chemist (Retired)/Collaborator U.S. Department of Agriculture Agricultural Research Service Western Regional Research Center Albany, California. Diagram of a Wheat Kernel. starch granule. endosperm protein. - PowerPoint PPT Presentation
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Donald D. Kasarda, Ph.D.
Research Chemist (Retired)/Collaborator
U.S. Department of Agriculture
Agricultural Research Service
Western Regional Research Center
Albany, California
Gluten Proteins in Relation to
Celiac Disease
Diagram of aWheat Kernel
FLOUR PARTICLES
starch granule
endosperm protein
Glutamine/Proline Composition of Wheat Prolamins (Mole Percent)
gliadins
gliadins
LMW-glutenin subunits
HMW-glutenin subunits
Gln Pro Gln + Pro
43-54 20-29 63-83
36-42 15-19 51-61+
30-38 12-27 42-55
2-Dimensional electrophoretic pattern of gluten proteins
“Consensus” Repeat Types for Gluten Proteins
-P-Q-Q-P-(Y/F)-P-gliadins
-gliadins -Q-Q-P-Q-Q-P-F-P-
D-type -gliadins
B-type -gliadins -Q-Q-Q-F-P-
-Q-P-Q-Q-P-F-P-
LMW-glutenin subunits
HMW-glutenin subnits
-Q-Q-Q-Q-P-P-F-S-
-Q-Q-G-Y-Y-P-T-S-P-
Leu
GlyGln Gln Gln
Gln GlnPro Pro Pro
ProTyr
Phe
Molecular model of a 13-residue gliadin peptide (a 13-mer)
L-G-Q-Q-Q-P-FF-P-P-Q-Q-P-Y
Currently Favored Analytical Method for Gluten in Food
R-5 monoclonal antibody ELISA test is available commercially.
Detection down to about 1.5 parts per million; quantification above 2.5 parts per million has been reported.
Antibody reacts with monomeric wheat, rye, and barley prolamins, butnot oat avenins; reacts weakly or not at all with glutelins (glutenin).
The Codex Alimentarius Committee on Methods agreed in 2004 to endorse temporarily the R5 ELISA for the determination of gluten.
Possible problems: failure to detect glutelin (glutenin) proteins andsmall peptides from hydrolysates.
Recognizes QQPFP and LQPFP motifs most strongly.