2j32: Difference between revisions
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Revision as of 19:18, 5 November 2007
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THE ROLE OF LOOP BUNDLE HYDROGEN BONDS IN THE MATURATION AND ACTIVITY OF(PRO)CASPASE-3
OverviewOverview
During maturation, procaspase-3 is cleaved at D175, which resides in a, linker that connects the large and small subunits. The intersubunit linker, also connects two active site loops that rearrange following cleavage and, in part, form the so-called loop bundle. As a result of chain cleavage, new hydrogen bonds and van der Waals contacts form among three active site, loops. The new interactions are predicted to stabilize the active site., One unresolved issue is the extent to which the loop bundle residues also, stabilize the procaspase active site. We examined the effects of replacing, four loop bundle residues (E167, D169, E173, and Y203) on the biochemical, and structural properties of the (pro)caspase. We show that replacing the, residues affects the activity of the procaspase as well as the mature, caspase, with D169A and E167A replacements having the largest effects., Replacement of D169 prevents caspase-3 autoactivation, and its cleavage at, D175 no longer leads to an active enzyme. In addition, the E173A mutation, when coupled to a second mutation in the procaspase, D175A, may alter the, substrate specificity of the procaspase. The mutations affected the active, site environment as assessed by changes in fluorescence emission, accessibility to quencher, and cleavage by either trypsin or V8 proteases., High-resolution X-ray crystallographic structures of E167A, D173A, and, Y203F caspases show that changes in the active site environment may be due, to the increased flexibility of several residues in the N-terminus of the, small subunit. Overall, the results show that these residues are important, for stabilizing the procaspase active site as well as that of the mature, caspase.
About this StructureAbout this Structure
2J32 is a Single protein structure of sequence from Homo sapiens with ACE as ligand. Structure known Active Site: AC1. Full crystallographic information is available from OCA.
ReferenceReference
Role of loop bundle hydrogen bonds in the maturation and activity of (Pro)caspase-3., Feeney B, Pop C, Swartz P, Mattos C, Clark AC, Biochemistry. 2006 Nov 7;45(44):13249-63. PMID:17073446
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