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Crystal Belonging (crystal + belonging)

Distribution by Scientific Domains
Chemistry100%

Selected Abstracts

Structure of an aliphatic amidase from Geobacillus pallidus RAPc8

ACTA CRYSTALLOGRAPHICA SECTION D, Issue 10 2007
Serah W. Kimani
The amidase from Geobacillus pallidus RAPc8, a moderate thermophile, is a member of the nitrilase superfamily and catalyzes the conversion of amides to the corresponding carboxylic acids and ammonia. It shows both amide-hydrolysis and acyl-transfer activities and also exhibits stereoselectivity for some enantiomeric substrates, thus making it a potentially important industrial catalyst. The crystal structure of G. pallidus RAPc8 amidase at a resolution of 1.9,Å was solved by molecular replacement from a crystal belonging to the primitive cubic space group P4232. G. pallidus RAPc8 amidase is homohexameric in solution and its monomers have the typical nitrilase-superfamily ,-,-,-, fold. Association in the hexamer preserves the eight-layered ,-,-,-,:,-,-,-, structure across an interface which is conserved in the known members of the superfamily. The extended carboxy-terminal tail contributes to this conserved interface by interlocking the monomers. Analysis of the small active site of the G. pallidus RAPc8 amidase suggests that access of a water molecule to the catalytic triad (Cys, Glu, Lys) side chains would be impeded by the formation of the acyl intermediate. It is proposed that another active-site residue, Glu142, the position of which is conserved in the homologues, acts as a general base to catalyse the hydrolysis of this intermediate. The small size of the substrate-binding pocket also explains the specificity of this enzyme for short aliphatic amides and its asymmetry explains its enantioselectivity. [source]

Crystallization and preliminary X-ray crystallographic studies of omega-transaminase from Vibrio fluvialis JS17

ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 8 2010
Tae-ho Jang
Omega-transaminase (,-TA) catalyzes the transfer of an amino group from a non-,-position amino acid or an amine compound with no carboxylic group to an amino acceptor. ,-TA from Vibrio fluvialis JS17 (,-TAVf) is a novel amine:pyruvate transaminase that is capable of stereoselective transamination of aryl chiral amines. In this study, ,-TAVf was overexpressed in Escherichia coli with engineered C-terminal His tags. ,-TAVf was then purified to homogeneity and crystallized at 292,K. X-ray diffraction data were collected to a resolution of 2.5,Å from a crystal belonging to the orthorhombic space group P212121, with unit-cell parameters a = 78.43, b = 95.95, c = 122.89,Å. [source]

Cloning, expression, crystallization and preliminary X-ray crystallographic analysis of glutamyl-tRNA synthetase (Xoo1504) from Xanthomonas oryzae pv. oryzae

ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 1 2009
Thanh Thi Ngoc Doan
The gltX gene from Xanthomonas oryzae pv. oryzae (Xoo1504) encodes glutamyl-tRNA synthetase (GluRS), one of the most important enzymes involved in bacterial blight (BB), which causes huge production losses of rice worldwide. GluRS is a class I-type aminoacyl-tRNA synthetase (aaRS) that is primarily responsible for the glutamylation of tRNAGlu. It plays an essential role in protein synthesis, as well as the regulation of cells, in all organisms. As it represents an important target for the development of new antibacterial drugs against BB, determination of the three-dimensional structure of GluRS is essential in order to understand its catalytic mechanism. In order to analyze its structure and function, the gltX gene was cloned and the GluRS enzyme was expressed, purified and then crystallized. A GluRS crystal belonging to the monoclinic space group C2 diffracted to 2.8,Å resolution and had unit-cell parameters a = 186.8, b = 108.4, c = 166.1,Å, , = 96.3°. The unit-cell volume of the crystal allowed the presence of six to eight monomers in the asymmetric unit, with a corresponding Matthews coefficient (VM) range of 2.70,2.02,Å3,Da,1 and a solvent-content range of 54.5,39.3%. [source]

Structure of 3(17),-hydroxysteroid dehydrogenase (AKR1C21) holoenzyme from an orthorhombic crystal form: an insight into the bifunctionality of the enzyme

ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 10 2007
Urmi Dhagat
Mouse 3(17),-hydroxysteroid dehydrogenase (AKR1C21) is a bifunctional enzyme that catalyses the oxidoreduction of the 3- and 17-hydroxy/keto groups of steroid substrates such as oestrogens, androgens and neurosteroids. The structure of the AKR1C21,NADPH binary complex was determined from an orthorhombic crystal belonging to space group P212121 at a resolution of 1.8,Å. In order to identify the factors responsible for the bifunctionality of AKR1C21, three steroid substrates including a 17-keto steroid, a 3-keto steroid and a 3,-hydroxysteroid were docked into the substrate-binding cavity. Models of the enzyme,coenzyme,substrate complexes suggest that Lys31, Gly225 and Gly226 are important for ligand recognition and orientation in the active site. [source]