title: Crystallization and preliminary X-ray diffraction analysis of HeLp, a heme lipoprotein from the hemolymph of the cattle tick Boophilus microplus.
abstract: The main protein present in the hemelymph of the cattle tick Boophilus microplus is a lipoprotein able to bind heme (HeLp). It has an apparent molecular weight of 354 000 Da and is composed of two polypeptide chains found in stoichiometric amounts. It contains 33% lipids. The protein was crystallized using the hanging-drop vapour-diffusion method in the presence of 1,6-hexanediol as a precipitant. X-ray diffraction data were collected to 2.1 A resolution using a synchrotron-radiation source. The crystal belongs to the triclinic space group P1, with unit-cell parameters a = 90.58, b = 105.50, c = 116.14 A, alpha = 112.40, beta = 111.64, gamma = 91.35 degrees. Owing to the lack of information about the amino-acid sequence, the structure of HeLp will be solved by the use of heavy atoms. Several possible derivatives have been collected and analysis is under way.
authors.affiliation: Departamento de Bioquímica Médica, Instituto de Ciências Biomédicas, Universidade Federal de Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Liliane Rosa
authors.initials: LR
authors.lastname: Alves
authors.forename: Pedro Lagerbald
authors.initials: PL
authors.lastname: Oliveira
authors.forename: João Alexandre Ribeiro Gonçalves
authors.initials: JA
authors.lastname: Barbosa
authors.forename: Beatriz Gomes
authors.initials: BG
authors.lastname: Guimarães
authors.forename: Francisco Javier
authors.initials: FJ
authors.lastname: Medrano
mesh_terms: D000818:Animals; D001059:Apoproteins / Q000737:chemistry; D001798:Blood Proteins / Q000737:chemistry*; D002417:Cattle; D003460:Crystallization; D003627:Data Interpretation, Statistical; D006458:Hemolymph / Q000737:chemistry*; D008970:Molecular Weight; D011485:Protein Binding; D011487:Protein Conformation; D013987:Ticks / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D001059:Apoproteins; D001798:Blood Proteins