Abstract
One of the main culprits of Alzheimerโs disease (AD) is the formation of toxic amyloid-ฮฒ (Aฮฒ) peptide polymers and the aggregation of Aฮฒ to form plaques in the brain. We have developed techniques to purify the catalytic domain of plasmin, micro-plasmin (ยตPlm), which can be used for an Aฮฒ-clearance based AD therapy. However, in serum, ยตPlm is irreversibly inhibited by its principal inhibitor ฮฑ2-antiplasmin (ฮฑ2-AP). In this study, we engineered and selected mutant forms of ยตPlm that are both catalytically active and insensitive to ฮฑ2-AP inhibition. We identified surface residues of ฮผPlm that might interact and bind ฮฑ2-AP, and used an alanine-scanning mutagenesis method to select residues having higher activity but lower ฮฑ2-AP inhibition. Then we employed saturation mutagenesis for further optimize both properties. Modeled complex structure of ยตPlm/ฮฑ2-AP shows that F587 is a critical contact residue, which can be used as a starting position for further investigation.
Highlights
One of the main culprits of Alzheimerโs disease (AD) is the formation of toxic amyloid-ฮฒ (Aฮฒ) peptide polymers and the aggregation of Aฮฒ to form plaques in the brain
Molecular dynamics (MD) simulation lasting 100 ns show that the C-terminal tail (CTT) is flexible and can have transient interactions with the neighborhood ฮผPlm, and these secondary, non-specific interactions may explain the surprising effects of alanine mutations on these distant loops
We find that mutations in loop 6 result in dramatic loss of catalytic activity, which may be attributed to increased Km, especially for V720A and E724A
Summary
One of the main culprits of Alzheimerโs disease (AD) is the formation of toxic amyloid-ฮฒ (Aฮฒ) peptide polymers and the aggregation of Aฮฒ to form plaques in the brain. Results of nearly 30 years of research have mostly supported the amyloid cascade ยญhypothesis[9,10], stating that the overproduction of Aฮฒ peptides (mostly from genetic defect), or the failure to effectively clear this peptide (most of the sporadic AD cases), leads to AD through Aฮฒ toxicity and amyloid deposition The latter is thought to be involved in the formation of neurofibrillary ยญtangles[11]. The Aฮฒ production and clearance is a balanced biological process, including multiple actions of active and passive transport out of the brain, along with cell-mediated clearance, deposition into insoluble aggregates, and proteolytic degradation. Each of this process can act collectively or in concert to contribute Aฮฒ catabolism. It has been shown that plasmin can degrade and reduce the toxicity of both monomer and fibril Aฮฒ24,27
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
