A mode of action of divalent iron ions on the solubilization of pectin in dried soybeans

二价铁离子对干大豆中果胶溶解的作用方式

基本信息

批准号：
06680027
负责人：
NAKAMURA Yasuhiko
金额：
$ 1.41万
依托单位：
Kagoshima University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

项目摘要

The solubilization of pectin in soybeans when they were subjected to a two-step soaking, soaking first in iron (II) salt solution and then in sodium chloride solution, was studied by both of experiments and molecular orbital calculations.The soaking of soybeans in iron (II) salt solution resulted in the increased amount of water soluble pectin but not of sodium hexametaphosphate soluble pectin and hydrochloric acid soluble pectin in the soybeans. The solubilization of pectin in the soybeans was accelerated by successive soaking in a sodium chloride solution after soaking in the iron (II) salt solution and boiling thereafter. Gel-permeation chromatography indicated that the molecular weight of the pectin leached from iron (II) -soaked soybeans was slightly lower than that of pectin from control. Similar results were obtained from the experiments using alcohol insoluble solids (AIS) instead of soybeans. The amount of pectin liberated from AIS by digestion with enzymes was largest when it was digested with celullase, but the amount of pectin liberated by soaking in iron (II) salts solution was largest for protease-digested AIS.Geometry optimization of the monomer and dimer of alpha-D-galacturonate ion ^4C_1 conformation and the electrostatic potential suggested that one of the carboxyl oxygen atoms, the oxygen atom of the pyranose ring and the oxygen atom of the hydroxyl group at C (4) position coordinated to an iron (II) ion. A simultaneous coordination of carboxyl oxygen atoms of each of adjacent alpha-D-galacturonate ion residues was considered to be impossible due to the long distance between the two carboxyl groups.

通过实验和分子轨道计算，研究了大豆经铁(II)盐溶液和氯化钠溶液两步浸泡后，果胶在大豆中的溶解情况。 (II)盐溶液导致大豆中水溶性果胶含量增加，但六偏磷酸钠可溶性果胶和盐酸可溶性果胶含量不增加。通过在铁(II)盐溶液中浸泡后连续浸泡在氯化钠溶液中并随后煮沸，加速了大豆中果胶的溶解。凝胶渗透色谱分析表明，铁(II)浸泡大豆中浸出的果胶的分子量略低于对照的果胶。使用酒精不溶性固体（AIS）代替大豆的实验也得到了类似的结果。当用纤维素酶消化时，通过酶消化从AIS中释放的果胶量最大，但对于蛋白酶消化的AIS，通过浸泡在铁(II)盐溶液中释放的果胶量最大。单体和二聚体的几何优化α-D-半乳糖醛酸离子^4C_1构象和静电势表明羧基氧原子之一、吡喃糖环的氧原子和C(4)位羟基的氧原子与铁(II)离子配位。由于两个羧基之间的距离较长，每个相邻α-D-半乳糖醛酸离子残基的羧基氧原子的同时配位被认为是不可能的。