Redox Capacity of an Extracellular Matrix Protein Associated with Adhesion in Mytilus californianus.
Redox Capacity of an Extracellular Matrix Protein Associated with Adhesion in Mytilus californianus.
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DOI：
10.1021/acs.biochem.6b00044
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发表时间：
2016-04-05
期刊：
影响因子：
2.9
通讯作者：
Waite JH
中科院分区：
文献类型：
--
作者：
Nicklisch SC;Spahn JE;Zhou H;Gruian CM;Waite JH
粘性贻贝足蛋白（Mfps）部分依赖于DOPA（3，4-二羟基苯基-1-丙氨酸）侧链来介导水下矿物表面的附着。DOPA氧化成多巴醌（Q）有效地消除了Mfps对这些表面的吸附。富含巯基的贻贝足蛋白-6（Mfp-6）通过将Q还原回DOPA来挽救由外源性DOPA氧化损害的粘附。通过使用非特异性显色探针与氧化还原池平衡来研究脚提取的Mfp-6的氧化还原化学和动力学。Footexperiment Mfp-6的还原能力为每个蛋白质约17 e−;其中一半来自半胱氨酸残基，而另一半来自其他成分，可能是Mfp-6中的四个或五个非粘附性氧化还原活性DOPA残基，其阳极峰电位比半胱氨酸氧化为胱氨酸的峰电位低约500 mV。在较高pH下，DOPA氧化还原可逆性可能由于Cys硫醇盐的Q清除而丧失。通过一维和二维质子核磁共振分析，在脚提取的Mfp-6蛋白中鉴定出具有疏水核心的明显β-折叠结构。该结构赋予Mfp-6中的氧化还原活性侧链，即，半胱氨酸和DOPA，在宽pH范围内具有显著的还原能力，并且这种能力在重组Mfp-6中可测量地降低。
Adhesive mussel foot proteins (Mfps) rely in part on DOPA (3,4-dihydroxyphenyl-l-alanine) side chains to mediate attachment to mineral surfaces underwater. Oxidation of DOPA to Dopaquinone (Q) effectively abolishes the adsorption of Mfps to these surfaces. The thiol-rich mussel foot protein-6 (Mfp-6) rescues adhesion compromised by adventitious DOPA oxidation by reducing Q back to DOPA. The redox chemistry and kinetics of foot-extracted Mfp-6 were investigated by using a nonspecific chromogenic probe to equilibrate with the redox pool. Footextracted Mfp-6 has a reducing capacity of ~17 e− per protein; half of this comes from the cysteine residues, whereas the other half comes from other constituents, probably a cohort of four or five nonadhesive, redox-active DOPA residues in Mfp-6 with an anodic peak potential ~500 mV lower than that for oxidation of cysteine to cystine. At higher pH, DOPA redox reversibility is lost possibly due to Q scavenging by Cys thiolates. Analysis by one- and two-dimensional proton nuclear magnetic resonance identified a pronounced β-sheet structure with a hydrophobic core in foot-extracted Mfp-6 protein. The structure endows redox-active side chains in Mfp-6, i.e., cysteine and DOPA, with significant reducing power over a broad pH range, and this power is measurably diminished in recombinant Mfp-6.