Structure
Flexibility and plasticity allow proteins to bind to ligands, form oligomers, aggregate, and perform mechanical work. Large conformational changes in proteins play an important role in cellular signaling. Adenylate Kinase is a signal transducing protein; thus, the balance between conformations regulates protein activity. ADK has a locally unfolded state that becomes depopulated upon binding.
A 2007 study by Whitford et al. shows the conformations of ADK when binding with ATP or AMP. The study shows that there are three relevant conformations or structures of ADK—CORE, Open, and Closed. In ADK, there are two small domains called the LID and NMP. ATP binds in the pocket formed by the LID and CORE domains. AMP binds in the pocket formed by the NMP and CORE domains.
The study also reported findings that show that localized regions of a protein unfold during conformational transitions. This mechanism reduces the strain and enhances catalytic efficiency. Local unfolding is the result of competing strain energies in the protein. The interconversion between inactive (open) and active (closed) conformations is rate limiting for catalysis.
Read more about this topic: Adenylate Kinase
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