title: 3-Carboxy-cis,cis-muconate lactonizing enzyme from Neurospora crassa: MAD phasing with 80 selenomethionines.
abstract: The structure of 3-carboxy-cis,cis-muconate lactonizing enzyme from Neurospora crassa was determined at 3.0 A resolution. Phase information was derived from a multiwavelength anomalous dispersion (MAD) experiment conducted at three wavelengths using crystals of fully substituted selenomethionine protein. However, the structure determination was not routine owing to the relatively poor quality of the diffraction data and the large number of twofolds in the unit cell. Eventually, 80 selenium sites were identified by the combined use of direct methods and real-space map interpretation. This represents one of the largest selenium substructures solved and used for phasing. Some of the difficulties in the structure determination and the methods used to address them are discussed.
authors.affiliation: Institute of Biotechnology, PO Box 56, University of Helsinki, FIN-00014 Helsinki, Finland.
authors.forename: Michael C
authors.initials: MC
authors.lastname: Merckel
authors.forename: Tommi
authors.initials: T
authors.lastname: Kajander
authors.forename: Ashley M
authors.initials: AM
authors.lastname: Deacon
authors.forename: Andrew
authors.initials: A
authors.lastname: Thompson
authors.forename: J Günter
authors.initials: JG
authors.lastname: Grossmann
authors.forename: Nisse
authors.initials: N
authors.lastname: Kalkkinen
authors.forename: Adrian
authors.initials: A
authors.lastname: Goldman
mesh_terms: D018360:Crystallography, X-Ray; D019753:Intramolecular Lyases / Q000737:chemistry*; D013058:Mass Spectrometry; D008958:Models, Molecular; D009492:Neurospora crassa / Q000201:enzymology*; D011487:Protein Conformation; D012645:Selenomethionine / Q000737:chemistry; D055672:Static Electricity
chemical_list: D012645:Selenomethionine; D019753:Intramolecular Lyases; C019831:3-carboxy-cis-cis-muconate cyclase