Matteucci G, Lanzara V, Ferrari C, Hanau S, Bergamini C M
Department of Biochemistry and Molecular Biology, University of Ferrara, Italy.
Biol Chem. 1998 Jul;379(7):921-4.
Tissue-type transglutaminase is inactivated in a time-dependent way during incubation with submillimolar concentrations of o-phthalaldehyde, with affinity labeling kinetics. The rate of inactivation by the reagent is greatly enhanced in the presence of the essential enzyme cofactor calcium and is decreased by GTP, an allosteric inhibitor. A fluorescent isoindole derivative is formed during the modification apparently through crosslinkage of active site Cys 277 to a lysine residue. These data and the quenching of fluorescence by addition of calcium ions suggest that the enzyme active site is directly involved in the inactivation process.
在与亚毫摩尔浓度的邻苯二甲醛孵育期间，组织型转谷氨酰胺酶以依赖时间的方式失活，具有亲和标记动力学。在必需的酶辅因子钙存在下，试剂的失活速率大大提高，而变构抑制剂GTP则使其降低。在修饰过程中显然通过活性位点半胱氨酸277与赖氨酸残基的交联形成了一种荧光异吲哚衍生物。这些数据以及加入钙离子导致的荧光猝灭表明酶活性位点直接参与了失活过程。
