Silva E, Edwards A M, Faljoni-Alario A
Facultad de Química, Pontificia Universidad Católica de Chile, Santiago.
Arch Biochem Biophys. 1990 Feb 1;276(2):527-30. doi: 10.1016/0003-9861(90)90754-m.
A study of the effects of deglycosylation of horseradish peroxidase on protein conformation, as well as on its catalytic activity of oxidation of isobutyraldehyde or its enol form to triplet acetone and formic acid, was performed. The loss of carbohydrates leads to structural modifications of this enzyme. This is confirmed by a change in the circular dichroism spectrum, an increase in tryptophan's environment polarity, and a loss of the chiral specificity toward D- and L-tryptophan. Deglycosylation does not destroy either the peptide backbone or the amino acid residues and does not affect the heme group content of the protein. The rates of oxygen uptake and light emission observed when horseradish peroxidase oxidizes isobutyraldehyde or the trimethylsilyl enol ether form of the latter are reduced when the enzyme is 70% deglycosylated. Concomitantly, the acting deglycosylated enzyme becomes inactivated during the course of the reaction. It appears that the carbohydrate moiety plays an important role in the protection of the peroxidase from damaging effects induced by triplet acetone and in the stabilization of the three-dimensional structure of this enzyme.
开展了一项关于辣根过氧化物酶去糖基化对蛋白质构象及其将异丁醛或其烯醇形式氧化为三重态丙酮和甲酸的催化活性影响的研究。碳水化合物的缺失导致该酶的结构发生修饰。这通过圆二色光谱的变化、色氨酸周围环境极性的增加以及对D-和L-色氨酸手性特异性的丧失得以证实。去糖基化既不破坏肽主链也不破坏氨基酸残基，并且不影响蛋白质的血红素基团含量。当辣根过氧化物酶氧化异丁醛或其三甲硅烷基烯醇醚形式时，观察到的氧气摄取速率和发光速率在酶70%去糖基化时降低。同时，起作用的去糖基化酶在反应过程中失活。看来碳水化合物部分在保护过氧化物酶免受三重态丙酮诱导的破坏作用以及在稳定该酶的三维结构方面起着重要作用。
