Ningthoujam Debananda S, Mukherjee Saikat, Devi Laishram Jaya, Singh Elangbam Shanta, Tamreihao Keising, Khunjamayum Rakhi, Banerjee Sumita, Mukhopadhyay Debashis
Department of Biochemistry, Advanced Level State Biotech Hub, Microbial Biotechnology Research Laboratory, Manipur University, Imphal, Manipur, India.
Department of Oral Pathology, Dental College, Regional Institute of Medical Sciences, Imphal, Manipur, India.
Alzheimers Dement (N Y). 2019 May 16;5:154-163. doi: 10.1016/j.trci.2019.03.003. eCollection 2019.
Amyloid fibrils are misfolded, protease-resistant forms of normal proteins. They are infectious such as prions or noninfectious such as β-amyloid (Aβ) fibrils causing Alzheimer's disease (AD). Prions and amyloids are structurally similar, possessing cross β-pleated sheet-like structures. As microbial keratinase could degrade prions, we tested keratinase activity on Aβ fibrils.
Lysozyme treated with urea generates Aβ fibrils demonstrated by immunoblotting with anti-Aβ antibody, high-performance liquid chromatography, and Congo red absorption spectroscopy. Two keratinases, Ker1 and Ker2, were purified from an actinomycete Amycolatopsis sp. MBRL 40 and incubated with Aβ fibrils.
Soluble Ker1 and Ker1 reconstituted on neutral/cationic liposomes degraded Aβ fibrils efficiently. Ker 2 was less potent.
Drugs that target AD inhibit acetylcholinesterase or formation of Aβ fibrils and downstream effects. These drugs have side effects and do not benefit globally in cognition. Keratinases are novel molecules for drug development against AD.
淀粉样纤维是正常蛋白质错误折叠且具有蛋白酶抗性的形式。它们具有传染性，如朊病毒，或不具有传染性，如导致阿尔茨海默病（AD）的β-淀粉样蛋白（Aβ）纤维。朊病毒和淀粉样蛋白在结构上相似，都具有交叉β-折叠片状结构。由于微生物角蛋白酶可以降解朊病毒，我们测试了角蛋白酶对Aβ纤维的活性。
用尿素处理的溶菌酶产生Aβ纤维，通过用抗Aβ抗体进行免疫印迹、高效液相色谱和刚果红吸收光谱法进行证明。从放线菌嗜皮菌属MBRL 40中纯化出两种角蛋白酶Ker1和Ker2，并与Aβ纤维一起孵育。
在中性/阳离子脂质体上重构的可溶性Ker1和Ker1能有效降解Aβ纤维。Ker2的效果较差。
针对AD的药物可抑制乙酰胆碱酯酶或Aβ纤维的形成及下游效应。这些药物有副作用，且在认知方面并非对所有人都有益。角蛋白酶是用于开发抗AD药物的新型分子。
