title: Crystallization and preliminary X-ray diffraction studies of the glutaminyl cyclase from Carica papaya latex.
abstract: In living systems, the intramolecular cyclization of N-terminal glutamine residues is accomplished by glutaminyl cyclase enzymes (EC 2.3.2.5). While in mammals these enzymes are involved in the synthesis of hormonal and neurotransmitter peptides, the physiological role played by the corresponding plant enzymes still remains to be unravelled. Papaya glutaminyl cyclase (PQC), a 33 kDa enzyme found in the latex of the tropical tree Carica papaya, displays an exceptional resistance to chemical and thermal denaturation as well as to proteolysis. In order to elucidate its enzymatic mechanism and to gain insights into the structural determinants underlying its remarkable stability, PQC was isolated from papaya latex, purified and crystallized by the hanging-drop vapour-diffusion method. The crystals belong to the orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 62.82, b = 81.23, c = 108.17 A and two molecules per asymmetric unit. Diffraction data have been collected at ESRF beamline BM14 and processed to a resolution of 1.7 A.
authors.affiliation: Laboratoire de Chimie Générale I, Faculté de Médecine-ULB CP609, 808 Route de Lennik, B-1070 Brussels, Belgium.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Azarkan
authors.forename: Bernard
authors.initials: B
authors.lastname: Clantin
authors.forename: Coralie
authors.initials: C
authors.lastname: Bompard
authors.forename: Hassan
authors.initials: H
authors.lastname: Belrhali
authors.forename: Danielle
authors.initials: D
authors.lastname: Baeyens-Volant
authors.forename: Yvan
authors.initials: Y
authors.lastname: Looze
authors.forename: Vincent
authors.initials: V
authors.lastname: Villeret
authors.forename: René
authors.initials: R
authors.lastname: Wintjens
mesh_terms: D019881:Aminoacyltransferases / Q000737:chemistry* / Q000302:isolation & purification*; D029441:Carica / Q000201:enzymology*; D003460:Crystallization; D007840:Latex / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D007840:Latex; D019881:Aminoacyltransferases; C059280:glutaminyl-peptide cyclotransferase