1m4t

Biosynthetic thiolase, Cys89 butyrylated

spinqualitylabelsall models 1m4t, resolution 1.77Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1m4t is a 4 chain structure with sequence from Zoogloea ramigera. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.77Å Ligands: CY4, GOL, SO4 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function THIL_SHIZO 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 PubMed Biosynthetic thiolase catalyzes the formation of acetoacetyl-CoA from two molecules of acetyl-CoA. This is a key step in the synthesis of many biological compounds, including steroid hormones and ketone bodies. The thiolase reaction involves two chemically distinct steps; during acyl transfer, an acetyl group is transferred from acetyl-CoA to Cys89, and in the Claisen condensation step, this acetyl group is further transferred to a second molecule of acetyl-CoA, generating acetoacetyl-CoA. Here, new crystallographic data for Zoogloea ramigera biosynthetic thiolase are presented, covering all intermediates of the thiolase catalytic cycle. The high-resolution structures indicate that the acetyl group goes through four conformations while being transferred from acetyl-CoA via the acetylated enzyme to acetoacetyl-CoA. This transfer is catalyzed in a rigid cavity lined by mostly hydrophobic side chains, in addition to the catalytic residues Cys89, His348, and Cys378. The structures highlight the importance of an oxyanion hole formed by a water molecule and His348 in stabilizing the negative charge on the thioester oxygen atom of acetyl-CoA at two different steps of the reaction cycle. Another oxyanion hole, composed of the main chain nitrogen atoms of Cys89 and Gly380, complements a negative charge of the thioester oxygen anion of the acetylated intermediate, stabilizing the tetrahedral transition state of the Claisen condensation step. The reactivity of the active site may be modulated by hydrogen bonding networks extending from the active site toward the back of the molecule. The catalytic cycle of biosynthetic thiolase: a conformational journey of an acetyl group through four binding modes and two oxyanion holes.,Kursula P, Ojala J, Lambeir AM, Wierenga RK Biochemistry. 2002 Dec 31;41(52):15543-56. PMID:12501183 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Thiolase 3D structures

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