Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01189 (beta-endorphin)
 21,003 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Treatment of an N-terminal-containing His6-tagged insulysin (His6-IDE) with proteinase K led to the initial cleavage of the His tag and linker region. This was followed by C-terminal cleavages resulting in intermediate fragments of approximately 95 and approximately 76 kDa and finally a relatively stable approximately 56 kDa fragment. The approximately 76 and approximately 56 kDa fragments exhibited a low level of catalytic activity but retained the ability to bind the substrate with a similar affinity as the native enzyme. The kinetics of the reaction of the IDE approximately 76 and approximately 56 kDa proteolytic fragments with a synthetic fluorogenic substrate produced hyperbolic substrate versus velocity curves, rather than the sigmoidal curve obtained with His6-IDE. The approximately 76 and approximately 56 kDa IDE proteolytic fragments were active toward the physiological peptides beta-endorphin, insulin, and amyloid beta peptide 1-40. Although activity was reduced by a factor of approximately 103-104 with these substrates, the relative activity and the cleavage sites were unchanged. Both the approximately 76 and approximately 56 kDa fragments retained the regulatory cationic binding site that binds ATP. Thus, the two proteinase K cleavage fragments of IDE retain the substrate- and ATP-binding sites but have low catalytic activity and lose the allosteric kinetic behavior of IDE. These data suggest a role of the C-terminal region of IDE in allosteric regulation.
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PMID:Proteolytic fragments of insulysin (IDE) retain substrate binding but lose allosteric regulation. 1715 46

Insulin-degrading enzyme (IDE) or insulysin is a highly conserved Zn(2+) -dependent endopeptidase with an "inverted" HxxEH motif. In vivo, IDE contributes to regulate the steady state levels of peripheral insulin and cerebral amyloid beta peptide (Abeta) of Alzheimer's disease. In vitro, substrates of IDE include a broad spectrum of peptides with relevant physiological functions such as atrial natriuretic factor, insulin-like growth factor-II, transforming growth factor-alpha, beta-endorphin, amylin or glucagon. The recently solved crystal structures of an inactive IDE mutant bound to four different substrates indicate, in accordance with previous compelling biochemical data, that peptide backbone conformation and size are major determinants of IDE recognition and substrate selectivity. IDE-N and IDE-C halves contribute to substrate binding and may rotate away from each other leading to open and closed conformers that permit or preclude the entry of substrates. Noteworthy, stabilization of substrate beta strands in their IDE-bound form may explain the preference of IDE for peptides with a high tendency to self-assembly as amyloid fibrils. These structural requirements may underlie the capability of some amyloid peptides of forming extremely stable complexes with IDE and raise the possibility of a dead-end chaperone-like function of IDE independent of catalysis. Furthermore, the recent recognition of IDE as a varicella zoster virus receptor and its putative involvement in muscle cell differentiation, steroid receptor signaling or proteasome modulation suggest that IDE is a multi-functional protein with broad and relevant roles in several basic cellular processes. Accordingly, IDE functions, regulation or trafficking may partake in the molecular pathogenesis of major human diseases and become potential targets for therapeutic intervention.
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PMID:Insulin-degrading enzyme: structure-function relationship and its possible roles in health and disease. 1992 17