Balog E, Kis-Petik K, Fidy J, Köhler M, Friedrich J
Institute of Biophysics, Semmelweis University of Medicine, Budapest, Hungary.
Biophys J. 1997 Jul;73(1):397-405. doi: 10.1016/S0006-3495(97)78079-2.
Mg-mesoporphyrin horseradish peroxidase (MgMP-HRP) and MgMP-HRP complexed with naphtohydroxamic acid (NHA) have been studied by fluorescence line narrowing (FLN) and pressure tuning spectral hole burning (SHB) techniques. In each sample, the low temperature absorption spectra show more than one transition in the origin range of the Q band. Comparisons with broad-band fluorescence spectra and FLN studies suggest that the multiple band feature originates from the presence of different configurations of the metal-porphyrin that are subject to Qx-Qy splitting within the protein cavity. This suggestion is supported by pressure tuning SHB studies. In the uncomplexed as well as in the NHA-complexed form of MgMP-HRP, irradiation in the Q band produces photoproduct bands, which has been attributed to a species with smaller Qx-Qy splitting. In an amorphous matrix, on the other hand, only one form of MgMP could be found, and no splitting could be observed. The binding of NHA does not significantly alter the bulk parameters of the protein matrix, but it reduces the structural variety in the configuration of MgMP to a single form with a more distorted structure and thus with an enlarged Qx-Qy splitting.
通过荧光线窄化（FLN）和压力调谐光谱烧孔（SHB）技术研究了镁-中卟啉辣根过氧化物酶（MgMP-HRP）以及与萘异羟肟酸（NHA）复合的MgMP-HRP。在每个样品中，低温吸收光谱在Q带的起始范围内显示出不止一个跃迁。与宽带荧光光谱和FLN研究的比较表明，多带特征源于金属卟啉不同构型的存在，这些构型在蛋白质腔内会发生Qx-Qy分裂。压力调谐SHB研究支持了这一观点。在未复合以及NHA复合形式的MgMP-HRP中，在Q带的辐照产生了光产物带，这归因于具有较小Qx-Qy分裂的物种。另一方面，在无定形基质中，只能发现一种形式的MgMP，并且未观察到分裂。NHA的结合不会显著改变蛋白质基质的整体参数，但它将MgMP构型的结构多样性降低到具有更扭曲结构且因此具有扩大的Qx-Qy分裂的单一形式。
