SURFACE STAINING OF WHEAT-STARCH GRANULES WITH REMAZOLBRILLIANT BLUE-R-DYE AND THEIR EXTRACTION WITH AQUEOUS SODIUM DODECYL-SULFATE AND MERCAPTOETHANOL
M. Seguchi, SURFACE STAINING OF WHEAT-STARCH GRANULES WITH REMAZOLBRILLIANT BLUE-R-DYE AND THEIR EXTRACTION WITH AQUEOUS SODIUM DODECYL-SULFATE AND MERCAPTOETHANOL, Cereal chemistry, 72(6), 1995, pp. 602-608
Wheat starch granules were strained with Remazolbrilliant blue R (RBB)
dye. The RBB-stained starch granules (RBB-starch) were successively e
xtracted with 1% sodium dodecyl sulfate (SDS) solution containing 1% 2
-mercaptoethanol-(2-ME) at room temperature for 1 day (extraction 1),
5 days (extraction 2), and 15 days (extraction 3). The stained molecul
es were solubilized first, an indication that the RBB dye was bound to
the granule surface. After each extraction with 1% SDS solution conta
ining 1% 2:ME, granules were examined by scanning electron microscopy.
The appearance of the residual starch structure changed greatly betwe
en extraction 2 and 3. After extraction 3, only a shell-like structure
was present. X-ray diffraction analysis of this sample indicated an a
bsence of crystallinity. The SDS extracts were subjected to Sepharose
CL-2B gel-filtration chromatography. Two blue peaks were observed for
extraction 1: one high and one low molecular size. The low molecular w
eight peak decreased for extraction 2 and was absent for extraction 3.
The high molecular weight blue peak did not disappear, although the r
atio of unstained carbohydrate to RBB-stained carbohydrate increased w
ith time. The low molecular weight blue peak was further subjected to
the Sephadex G-50 gel-filtration chromatography, and the resulting sin
gle peak was analyzed for sugars, proteins and peptides, and lipids. O
nly lipids were found. The main TLC spot was RBB stained and indicated
lysophosphatidylglycerol by Dittmer and periodate spray reagents.