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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
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
“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
Pro Tyr
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
NIQVDPSGQVQWPQQQQPFPQPQQPFSQQPQQIFPQPQQ -Gliadin sequence
TFPHQPQQAFPQPQQTFPHQPQQQFPQPQQPQQPFPQQP
QQQFPQPQQPQQPFPQQPQQQFPQPQQPQQPFPQPQQPQ
LPFPQQPQQPFPQPQQQPQQPFPQLQQPQQPLPQPQQPQ TTTVQYNPSEQYQPYPEQQEPFVQQQQPFVQQ Av Avenin Sequence QQPFPQQQQPLIQPYLQQQMNPCKNYLLQQCNPVSLVSSL QQPFVQQQQMFLQPLLQQQLNPCKQFLVQQCSPVAAVPFL Av
VSMILPRSDCKVMRQQCCQQLARIPQQLQCAAIHGIVHSI RSQILRGAICQVTRQQCCRQLAQIPEQLRCPAIHSVVQSI Av
IMQQEQQQQQQQQQQQQQGIQIMRPLFQQQQVGQGILVQG ILQQQQQQQQFIQPQLQQQVFQPQLQLQQQVFQPQMQ--- Av
--------------IIQPQQPAGLEVIRSLVLGTLPTMCN QLQQQVFQPQLQQVFNQPQMAGQIEGMRAFALQALPAMCD Av
VFVPPECSTTKAPFASIVADIGGQVYVPPQCPVATAPLGGF
(Avenins make up ~10% of oat proteins)
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.