Lysozyme modification by the Fenton reaction and gamma radiation
Lysozyme modification by the Fenton reaction and gamma radiation
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DOI：
10.1080/10715760290019291
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发表时间：
2002-03-01
影响因子：
3.3
通讯作者：
Lissi, E
中科院分区：
文献类型：
--
作者：
Edwards, AM;Ruiz, M;Lissi, E
比较了芬顿试剂（Fe（E）/H2 O2）和γ射线产生的羟基自由基对溶菌酶的修饰作用。调整条件以获得，与两个系统，50%的活性损失的改性的合奏。γ射线几乎修饰了酶中所有类型的氨基酸残基，但特异性很小。修饰顺序为Tyr >Met = Cys > Lys > Ile + Leu > Gly > Pro = Phe > Thr + Ala > Trp = Ser > Arg > Asp + Glu，每摩尔天然酶有42摩尔修饰残基。相反，当酶暴露于芬顿反应时，只有某些类型的氨基酸被修饰。此外，每初始摩尔酶的残基数量较少（13.5）被损坏。修饰顺序为Tyr > Cys > Trp > Met > His > Ile + Leu >瓦尔> Arg。这些结果表明，由这两种自由基源引起的修饰遵循不同的机制。分子内的自由基链反应，提出发挥主导作用的γ辐射促进蛋白质的氧化修饰。
A comparative study was performed on lysozyme modification after exposure to Fenton reagent (Fe(E)/H2O2) or hydroxyl radicals produced by gamma radiation. The conditions were adjusted to obtain, with both systems, a 50% loss of activity of the modified ensemble. gamma radiation modified almost all types of amino acid residues in the enzyme, with little specificity. The modification order was Tyr >Met = Cys > Lys > Ile + Leu > Gly > Pro = Phe > Thr + Ala > Trp = Ser > Arg > Asp + Glu, with 42 mol of modified residues per initial mole of native enzyme. In contrast, when the enzyme was exposed to the Fenton reaction, only some types of amino acids were modified. Furthermore, a smaller number of residues (13.5) were damaged per initial mole of enzyme. The order of the modified residues was Tyr > Cys > Trp > Met > His > Ile + Leu > Val > Arg. These results demonstrate that the modifications elicited by these two free radical sources follow different mechanisms. An intramolecular free radical chain reaction is proposed to play a dominant role in the oxidative modification of the protein promoted by gamma radiation.