Lewis C, Scouten W H
Biochim Biophys Acta. 1976 Aug 24;444(1):326-30. doi: 10.1016/0304-4165(76)90250-6.
Methylene blue immobilized on porous glass beads was used to catalyze the photooxidation of methionine alone and the methionine residues of lysozyme. A solution of 2 mM methionine in 50% acetic acid was oxidized to methionine sulfoxide in the presence of immobilized methylene blue after 6 h of photooxidation at 37 degrees C. Selective photooxidation of the methionyl residues in lysozyme was achieved after 26 h of reaction in 84% acetic acid at 4 degrees C. The specific activity of lysozyme exposed to light in the presence of methylene blue decreased by 94%, while that of a lysozyme solution in the presence of methylene blue not exposed to light decreased by 21%. The lysozyme solution exposed to light but not containing the methylene blue beads lost 33% of its specific activity after the same period of photooxidation. It was shown that the decrease in enzyme activity was not caused by adsorption of the enzyme onto the beads.
固定在多孔玻璃珠上的亚甲蓝用于催化蛋氨酸自身以及溶菌酶中蛋氨酸残基的光氧化反应。在37℃光氧化6小时后，2 mM蛋氨酸在50%乙酸中的溶液在固定化亚甲蓝存在下被氧化为蛋氨酸亚砜。在4℃的84%乙酸中反应26小时后，实现了溶菌酶中甲硫氨酰残基的选择性光氧化。在亚甲蓝存在下光照的溶菌酶比活性下降了94%，而在亚甲蓝存在下未光照的溶菌酶溶液比活性下降了21%。在相同的光氧化时间段后，光照但不含亚甲蓝珠的溶菌酶溶液比活性损失了33%。结果表明，酶活性的降低不是由酶吸附到珠子上引起的。
