Quintero Denny, Velasco Zoraida, Hurtado-Gómez Estefanía, Neira José L, Contreras Lellys M
Departamento de Biología, Facultad Experimental de Ciencias y Tecnología, Universidad de Carabobo, Valencia, Venezuela.
Biochim Biophys Acta. 2007 Apr;1774(4):510-8. doi: 10.1016/j.bbapap.2007.02.002. Epub 2007 Feb 13.
The isolation, purification, biochemical and biophysical characterization of the first reported beta-xylosidase from Geobacillus pallidus are described. The protein has an optimum pH close to 8 and an optimum temperature of 70 degrees C. These biochemical properties agree with those obtained by spectroscopic techniques, namely, circular dichroism (CD), infrared (FTIR) and fluorescence measurements. Thermal denaturation, followed by CD and FTIR, showed an apparent thermal denaturation midpoint close to 80 degrees C. The protein was probably a hydrated trimer in solution with, an elongated shape, as shown by gel filtration experiments. FTIR deconvolution spectra indicated that the protein contains a high percentage of alpha-helix (44%) and beta-sheet (40%). The sequencing of the N terminus and the biochemical features indicate that this new member of beta-xylosidases belongs to the GH52 family. Since there are no reported structural studies of any member of this family, our studies provide the first clue for the full conformational characterization of this protein family.
本文描述了从苍白嗜热栖热菌中首次报道的β-木糖苷酶的分离、纯化、生化及生物物理特性。该蛋白的最适pH接近8，最适温度为70℃。这些生化特性与通过光谱技术（即圆二色性（CD）、红外（FTIR）和荧光测量）获得的结果一致。热变性实验结合CD和FTIR表明，明显的热变性中点接近80℃。凝胶过滤实验表明，该蛋白在溶液中可能是一种水化三聚体，形状细长。FTIR去卷积光谱表明，该蛋白含有高比例的α-螺旋（44%）和β-折叠（40%）。N端测序和生化特征表明，这种新的β-木糖苷酶属于GH52家族。由于尚未有关于该家族任何成员的结构研究报道，我们的研究为全面表征该蛋白家族的构象提供了首个线索。
