254l
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LYSOZYME
OverviewOverview
Enzymes are thought to use their ordered structures to facilitate, catalysis. A corollary of this theory suggests that enzyme residues, involved in function are not optimized for stability. We tested this, hypothesis by mutating functionally important residues in the active site, of T4 lysozyme. Six mutations at two catalytic residues, Glu-11 and, Asp-20, abolished or reduced enzymatic activity but increased thermal, stability by 0.7-1.7 kcal.mol-1. Nine mutations at two substrate-binding, residues, Ser-117 and Asn-132, increased stability by 1.2-2.0 kcal.mol-1, again at the cost of reduced activity. X-ray crystal structures show that, the substituted residues complement regions of the protein surface that, are used for substrate recognition in the native enzyme. In two of these, structures the enzyme undergoes a general conformational change, similar, to that seen in an enzyme-product complex. These results support a, relationship between stability and function for T4 lysozyme. Other, evidence suggests that the relationship is general.
About this StructureAbout this Structure
254L is a Single protein structure of sequence from Bacteriophage t4 with CL and BME as ligands. Active as Lysozyme, with EC number 3.2.1.17 Full crystallographic information is available from OCA.
ReferenceReference
A relationship between protein stability and protein function., Shoichet BK, Baase WA, Kuroki R, Matthews BW, Proc Natl Acad Sci U S A. 1995 Jan 17;92(2):452-6. PMID:7831309
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