Chemistry of Cereal Grains - Sourdough Biotechnology - page 23

Table 2.5 Partial amino acid sequences of domain B of HMW-GS 1Dx2 (positions 93-338)
and of HMW-GS 1Dy10 (positions 106-380) [ 63 ]
Position

Sequence a Position Sequence a

93 YYPSVTSPQQVS 106 YYPGVTSPRQGS

105 YYPGQASPQRPGQG 118 YYPGQASPQQPGQG

119 QQPGQG 132 QQPGKW

125 QQSGQGQQG 138 QEPGQGQQW

134 YYP--TSPQQPGQW 147 YYP--TSLQQPGQG

146 QQPEQGQPG 159 QQIGKGQQG

155 YYP--TSPQQPGQL 168 YYP--TSLQQPGQGQQG

167 QQPAQG 183 YYP--TSLQHTGQR

173 QQPGQGQQG 195 QQPVQG

182 QQPGQGQPG 201 QQPEQG

191 YYP-TSSQLQPGQL 207 QQPGQWQQG

204 QQPAQGQQG 216 YYP--TSPQQLGQG

213 QQPGQGQQG 228 QQPRQW

222 QQPGQG 234 QQSGQGQQG

228 QQPGQGQQG 243 HYP--TSLQQPGQGQQG

237 QQPGQG 258 HYL--ASQQQPGQGQQG

243 QQPGQGQQG 273 HYP--ASQQQPGQGQQG

252 QQLGQGQQG 288 HYP--ASQQQPGQGQQG

261 YYP--TSLQQSGQGQPG 303 HYP--ASQQEPGQGQQG

276 YYP--TSLQQLGQGQSG 318 QIPASQ

291 YYP--TSPQQPGQG 324 QQPGQGQQG

303 QQPGQL 333 HYP--ASLQQPGQGQQG

309 QQPAQG 348 HYP--TSLQQLGQGQQT

315 QQPGQGQQG 363 QQPGQK

324 QQPGQGQQG 369 QQPGQG

333 QQPGQG 375 QQTGQG

a One-letter-code for amino acids; - deletion

The LMW group consists of monomeric proteins including a / b- and g -gliadins
of wheat, g-40 k-secalins of rye, g-hordeins of barley, and avenins of oats, and of
aggregative proteins including LMW-GS of wheat, g-75 k-secalins of rye, and
B-hordeins of barley (Table 2.4 ). They have around 300 amino acid residues and
MW ranging from 28,000-35,000, besides g-75 k-secalins (~430 residues, MW
~50,000) and avenins (~200 residues, MW ~23,000). The amino acid compositions
of the LMW group proteins are characterized by relatively high contents of hydro-
phobic amino acids besides glutamine and proline. The amino acid sequences consist
of four (a / b-gliadins five) different sequence sections (Fig. 2.1 ). The N-terminal
section I is rich in glutamine, proline, and phenylalanine forming repetitive units
such as QPQPFPPQQPY (a / b-gliadins), QQPQQPFP (g -gliadins), QQPPFS
(LMW-GS), or PFVQQQQ (avenins). Section I of g-75 k-secalins is prolonged by
around 130 residues as compared to g-40 k-secalins and that of avenins is shortened
to around 40 residues. Section II is unique to a / b-gliadins and consists of a polyglu-
tamine sequence (up to 18 Q-residues). Sections III, IV, and V possess more balanced