ABSTRACT
CutC is a novel copper homeostasis protein containing 248 amino acids. Here we report the cloning, expression, purification, crystallization and preliminary X-ray crystallographic studies of CutC from Shigella flexneri 2a. Purification of CutC and its selenomethionine (SeMet) derivate were done using immobilized metal ion affinity chromatography, size-exclusion and ion-exchange chromatography. The purified proteins were crystallized using the hanging drop vapor diffusion method. The diffraction data for the native and SeMet CutC, respectively, have been collected with resolution of 1.7 A and 2.1 A. They belong to the space group C2221 and similar cell dimension. The native protein crystals have cell parameters: a=75.3267, b=97.6718, c=132.6910.
Subject(s)
Bacterial Proteins/isolation & purification , Carrier Proteins/isolation & purification , Copper/chemistry , Crystallography, X-Ray/methods , Animals , Bacterial Proteins/chemistry , Carrier Proteins/chemistry , Escherichia coli/enzymology , Homeostasis , Recombinant Proteins/chemistry , Selenomethionine/chemistry , Shigella flexneri/chemistry , Shigella flexneri/enzymology , X-Ray Diffraction/methodsSubject(s)
Carrier Proteins/chemistry , Copper/chemistry , Crystallography, X-Ray/methods , Escherichia coli Proteins/chemistry , Shigella flexneri/metabolism , Amino Acid Sequence , Cloning, Molecular , Computational Biology/methods , Databases, Protein , Homeostasis , Intracellular Signaling Peptides and Proteins , Models, Molecular , Molecular Sequence Data , Protein Conformation , Protein Structure, Secondary , Sequence Homology, Amino Acid , X-Ray DiffractionABSTRACT
An alpha-like toxin named BmK M7 active on both mammals and insects has been purified from the venom of scorpion Buthus martensii Karsch (BmK) recently. The electrophysiological experiments showed that M7 can bind to human cardiac Na+-channel and modify its normal properties, hence can be considered as a cardiotoxin. Single crystals of M7 have been obtained by hanging-drop vapor diffusion method using ammonium sulfate as precipitant in Tris-HCl buffer at pH 8.5. A data set to 1.40 A resolution was collected using synchrotron radiation and CCD detector in Photon Factory in Japan. Data analysis showed that the crystals belonged to space group P3(1)21/P3(1)21, with cell dimensions a=b=32.76 A, c=176.82 A. Assuming two molecules per asymmetric unit, the Vm value is 1.92 A3/Da. The initial structural analysis was carried out by molecular replacement, which showed the correct space group (P3(1)21), and the orientations and positions of the two molecules in the asymmetric unit.
Subject(s)
Heart/drug effects , Scorpion Venoms/chemistry , Animals , Biological Assay , Crystallization , Crystallography, X-Ray , Houseflies/drug effects , Larva/drug effects , Scorpion Venoms/isolation & purification , Scorpion Venoms/toxicity , Sodium Channel BlockersABSTRACT
Two antifungal proteins, named Eucommia antifungal peptides 1 and 2 (EAFP1 and EAFP2), have been purified from the bark of the tree E. ulmoides Oliver and show a relatively broad spectrum of antifungal activity against several agriculturally important plant pathogens. One of these small proteins (EAFP2) has been crystallized. The crystal belongs to space group P2(1), with unit-cell parameters a = 19.01, b = 23.16, c = 30.69 A, beta = 98.54 degrees. 1.0 A resolution data were collected from an EAFP2 crystal and have been used to obtain phase information directly by an ab initio method.
Subject(s)
Antifungal Agents/chemistry , Disulfides/analysis , Eucommiaceae/chemistry , Plant Proteins/chemistry , Antifungal Agents/isolation & purification , Crystallography, X-Ray/methods , Plant Proteins/isolation & purification , TreesABSTRACT
As a special species of avian, Peking duck is often used as a model for exploring effective factors against cardio-cerebrovascular diseases, and therefore investigations of antioxidant enzymes including superoxide dismutase are intriguing. By using 3(')-RACE with a gene-specific primer, a cDNA encoding duck Cu,Zn SOD was amplified from the total RNA extracted from Peking duck liver. Three free cysteine residues are found in the deduced amino acid sequence of duck SOD, among which Cys153 at the carbonyl-terminal is a distinctive feature. Production with a high yield of recombinant duck Cu,Zn SOD was achieved in Escherichia coli after the reconstituted expression vector pET-3a-dSOD was transformed into the bacterial strain BL21(DE3)pLysS. After two steps of anion exchange chromatography, a great quantity of the purified enzyme (100mg/L fermented culture) with an enzymatic activity comparable to that of native duck and bovine SOD was finally obtained. Duck SOD is a homodimer with 153 residues for each subunit. The molecular mass of the recombinant enzyme is 15,540.0Da measured by mass spectrum, which well coincides with the estimated size of the sequence but significantly differs from that of the native counterpart. Five charge isomers were observed on isoelectricfocusing (IEF). The most interesting observation is that the thermal stability of duck SOD is much lower than that of the bovine enzyme as revealed by irreversible heat inactivation at 70 degrees C. These properties are discussed in relation to the distinctive free Cys residues in duck Cu,Zn SOD.
