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

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.