Structure of Lysophosphatidylglyceryl‐Remazolbrilliant Blue (LPG‐RBB) from the Surface of Dyed Wheat Starch Granules

Abstract

Cereal Chem. 75(3):294-296Wheat starch granule surface was covalently stained with Remazolbrilliant blue-R dye (RBB) and then extracted with 1% SDS containing 1% 2-mercaptoethanol (2-ME) at room temperature for 14.5 hr. The extracted blue-staining material (A 650 ) separated into two fractions. Low molecular weight (LMW) material was further purified by Sephadex G-75 size-exclusion chromatography and thin-layer chromatography. Infrared and nuclear magnetic resonance ( 1 H-NMR and 13 C-NMR) spectroscopy indicated that the structure of the purified LMW material was 18-O-(6lysophosphatidylglyceryl)-RBB.

Lipids of Wheat, Corn and Potato Starch

“…Using NMR spectroscopy in surface material analysis of wheat starch, it was found that lysophosphatidylcholine (LPC) was the main surface component extracted by Me/SDS (Jimeno et al 2002). Seguchi and Kanenaga (1998) isolated other phospholipids, namely lysophosphatidylglycerol (LPG), from wheat starch by mechanical forces (ie., 45 min of stirring). The presence ofphospholipids such as LPC, LPG, and lysophosphatidylethanolamine have previously been reported in wheat starch (Morrison 1983); however, this author postulated that the phospholipids seem to be a template for the amylose helix structure and are therefore important in maintaining the internal structure of starch.…”

13C and 1H NMR Study of Lysophosphatidylcholine (LPC) Isolated from the Surface of Wheat Starch Granules

“…LPC was the main compound of LMW material, which was removed from the surface of wheat starch after one fold extraction. In spite of clear signal peaks assigned to LPC, it was not possible to identify the LPG-RBB complex such as Seguchi and Kanenaga (1998) reported either in the 3.3-4.4 ppm range or in the aromatic region.…”

“…In any case we consider it of interest to comment that the assignment by Seguchi and Kanenaga (1998) is unusual because they assigned each aromatic carbon atom in a range of 2-4 ppm. This broad assignment may be explained by the fact that the RBB dye is not a single chemical species but rather a mixture of compounds.…”

“…Seguchi (1995) and Seguchi and Kanenaga (1997) removed surface material by washing wheat starch granules with 1% SDS containing 1% 2-mercapthoethanol. Before extraction starch was stained with a Remazolobrilliant Blue-R dye used as a marker for extracted surface molecules, therefore non-starch material was identified as HMW carbohydrates soluble in 1% SDS/ME and LMW non-starch lipids, both complexed with RBB; the main component of nonstarch lipids (LMW material) was analyzed as 18-O-(6-lysophosphadtidylglyceryl)-RBB complex (Seguchi and Kanenaga, 1998). It was also suggested that the lysophospholipids extracted from or near the surface of granules after 10 days of washing were probably complexed with amylose.…”

“…The starch extract was centrifuged at 1700 Â g for 20 min and supernatant was collected, dialyzed against water and freeze-dried and the remaining RBB-starch pellet continued to be five, ten and fifteen fold extracted. After each step of extraction the pellet was again resuspended in fresh aqueous 1% SDS/1% mercaptoethanol (Seguchi and Kanenaga, 1998).…”