1sqc
SQUALENE-HOPENE-CYCLASE FROM ALICYCLOBACILLUS ACIDOCALDARIUSSQUALENE-HOPENE-CYCLASE FROM ALICYCLOBACILLUS ACIDOCALDARIUS
Structural highlights
Function[SQHC_ALIAD] Catalyzes the cyclization of squalene into hopene. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe crystal structure of squalene-hopene cyclase from Alicyclobacillus acidocaldarius was determined at 2.9 angstrom resolution. The mechanism and sequence of this cyclase are closely related to those of 2,3-oxidosqualene cyclases that catalyze the cyclization step in cholesterol biosynthesis. The structure reveals a membrane protein with membrane-binding characteristics similar to those of prostaglandin-H2 synthase, the only other reported protein of this type. The active site of the enzyme is located in a large central cavity that is of suitable size to bind squalene in its required conformation and that is lined by aromatic residues. The structure supports a mechanism in which the acid starting the reaction by protonating a carbon-carbon double bond is an aspartate that is coupled to a histidine. Numerous surface alpha helices are connected by characteristic QW-motifs (Q is glutamine and W is tryptophan) that tighten the protein structure, possibly for absorbing the reaction energy without structural damage. Structure and function of a squalene cyclase.,Wendt KU, Poralla K, Schulz GE Science. 1997 Sep 19;277(5333):1811-5. PMID:9295270[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences |
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