title: Preparation of phytate-removed deamidated soybean globulins by ion exchangers and characterization of their calcium-binding ability.
abstract: Phytate-removed deamidated soybean globulins were prepared using ion-exchange resins to provide them with a functional property to enhance calcium absorption in the body. The phosphorus level was reduced from 45 to 20 micromol/g using 0.05 g/mL of AE-4, an anion-exchange resin with a (2-hydroxyethyl)dimethylammonium group, in 0.2% soybean globulin solution for 1 h at 4 degrees C, and 90-92% of the phosphorus in defatted soybeans could be removed. As for deamidation, CE-4, a cation-exchange resin of the carboxylate type, showed a much higher deamidation activity than CE-1 and CE-2, cation-exchange resins of the sulfonate type. No peptide bond hydrolysis was observed for any cation-exchange resin treated at 4 degrees C. There was no significant difference in the amount of acid amide deamidated at temperatures between 4 and 50 degrees C. The deamidation level was able to increase to 73% using 0.10 g/mL of CE-4 in a 0.2% soybean globulin solution for 6 h at 4 degrees C. The amount of calcium bound to the soybean globulins decreased with removal of the phytate but increased with deamidation.
authors.affiliation: Department of Agricultural and Biological Chemistry, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa-shi 252-8510, Japan. kumagai@brs.nihon-u.ac.jp
authors.forename: Hitomi
authors.initials: H
authors.lastname: Kumagai
authors.forename: Shigeo
authors.initials: S
authors.lastname: Ishida
authors.forename: Atsushi
authors.initials: A
authors.lastname: Koizumi
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Sakurai
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Kumagai
mesh_terms: D001682:Biological Availability; D002118:Calcium / Q000378:metabolism* / Q000493:pharmacokinetics; D003641:Deamination; D005916:Globulins / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D007408:Intestinal Absorption / Q000187:drug effects; D007475:Ion Exchange Resins / Q000737:chemistry*; D010758:Phosphorus / Q000032:analysis; D010833:Phytic Acid / Q000378:metabolism*; D013025:Glycine max / Q000737:chemistry*; D013696:Temperature
chemical_list: D005916:Globulins; D007475:Ion Exchange Resins; D010758:Phosphorus; D010833:Phytic Acid; D002118:Calcium