INTERACTION OF THIOL-TYPE THIAMINE WITH OXIDIZED EGG ALBUMIN AND ITS REACTION PRODUCTS

概要

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1. Thiamine-protein complex and non-bound disulfide-type thiamine are formed by the reaction of thiamine or O-benzoyl thiamine with the iodine-oxidized egg albumin at pH 7.3 or 9.0, and 37°. The thiamine bound with protein could not be separated from the protein by zone electrophoresis, dialysis at pH 3.0, deproteinization with metaphosphoric acid. However, free thiamine was easily liberated from the bound form by reduction with sodium thiosulfate or cysteine. These findings suggest that the compound is a protein-thiamine mixed disulfide produced by the interchange reaction of the thiol form of thiamine with the artificially produced SS-group of the oxidized protein.2. The amount of the bound form is by far greater at pH 9.0 than at pH 7.3, possibly due to the difference in the amount of thiol-type thiamine.3. In the reaction at the same pH level O-benzoyl thiamine was more reactive with oxidized protein than thiamine.4. The amount of bound thiamine produced in the reaction with the oxidized egg albumin rises with the amount of iodine used for oxidation of the protein, up to about 5 equivalents of iodine per mole of egg albumin. Beyond that value, the bound form did not increase, taking about the constant value within the range of 6 to 18 equivalents.
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