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1.
The non-heme iron protein, hemerythrin, has been crystallized from Themiste dyscritum. The crystals belong to the tetragonal space group P4 with unit cell dimensions a = b = 86.5 Å, c = 80.6 Å. A 2-fold molecular axis is suggested, implying that the asymmetric unit contains four subunits each with a molecular weight of 12,600.  相似文献   

2.
Conditions have been established for the crystallization of tyrosyl-transfer RNA synthetase from Bacillus stearothermophilus at room temperature. The crystals are extremely well-ordered, exhibiting diffraction spots out to at least 2.7 Å, and can be grown to a convenient size for X-ray crystallographic analysis. The crystals are trigonal with a space group P3121, the unit cell having dimensions of a = 64.4 A? and c = 238 A?; the crystallographic asymmetric unit is probably one subunit of the dimeric (2 × 45,000, mol. wt) enzyme. The enzyme crystals are extremely stable and exhibit good resistance to radiation damage. This amino-acyl-tRNA synthetase appears to be amenable to complete structure determination by X-ray crystallography.  相似文献   

3.
Single crystals of adenylosuccinate synthetase, an essential component of purine biosynthesis, extracted from rabbit skeletal muscle were prepared as suitable specimens for X-ray structure analysis. The crystal belongs to the space group P43212 or P41212 with unit cell dimensions a = b = 71.2 A?, c = 194.8 A?. The asymmetric unit contains one protein molecule of 54,000 molecular weight.  相似文献   

4.
Flavodoxin isolated from the blue-green alga, Anacystis nidulans, crystallizes from ammonium sulfate in space group P212121, with a = 57.08 Å, b = 69.24 Å and c = 45.55 Å. The diffraction patterns extend to a resolution of at least 1.8 Å. Reduction of the flavin mononucleotide in the crystalline protein, to either the semi-quinone or fully reduced (hydroquinone) state, results in minimal changes in cell dimensions and diffracted intensities. The higher molecular weight (19,000 to 20,000) and spectral properties of the A. nidulans protein, along with the near-isomorphism of crystals of the three oxidation states, distinguish this crystalline flavodoxin from the corresponding proteins of Clostaridium MP and Desulfovibrio vulgaris, whose three-dimensional structures are known. In contrast to Clostridium flavodoxins, but like the D. vulgaris protein, A. nidulans flavodoxin is capable of binding riboflavin in place of flavin mononucleotide (Ka = 2 × 106m−1).  相似文献   

5.
Crystals of mitogenic lectin from pea seeds (Pisum sativum) have been grown. The crystals are in space group P212121 with unit cell dimensions: a = 51.0 ± 0.2 A?, b = 617 ± 0.2 A?, c = 137.6 ± 0.5 A?. The asymmetric unit has one protein molecule.  相似文献   

6.
Reassembled alfalfa mosaic virus coat protein was partially digested with trypsin to remove the first 26 amino acids (Bol et al., 1974). These particles are empty icosahedral protein shells built with 60 alfalfa mosaic virus protein subunits. This aggregate has been crystallized in two different crystal forms, one of which diffracts X-rays to at least 3.4 Å resolution. The type I crystals (space group P63, a = 200 A?, c = 314 A?) contain two particles per cell separated by 195 Å with each sitting on a 3-fold axis. The type II crystals contain three particles per cell in space group P31or P32 (a = 201 A?, c = 485 A?). Other T = 1 viral particles have very similar diameters.  相似文献   

7.
The β-lactamase (penicillinase) from Escherichia coli W3310 has been crystallized from 25% saturated ammonium sulfate solution at pH 6.9. An X-ray examination of the monoclinic crystals shows the space group is C2, with unit cell dimensions a = 47.2 A?, b = 76.9 A?, c = 73.3 A? and β = 98.6°. With Z = 4 and the molecular weight = 22,000 (Melling &; Scott, 1972), the Å3/dalton ratio is 2.98. The crystals are suitable for structure analysis to at least 2.4 Å resolution.  相似文献   

8.
Purification and crystallisation procedures are reported for azurin and cytochrome c′ from Alcaligenes denitrificans and Alcaligenes sp. NCIB 11015. The azurin crystals from A. denitrificans are suitable for high-resolution X-ray structure analysis. They are orthorhombic, space group C2221 (with marked tetragonal pseudo-symmetry), cell dimensions a = 75.0 A?, b = 74.1 A?, c = 99.5 A?, with two molecules per asymmetric unit. The cytochrome c′ crystals from both species are hexagonal, space group P6122 (or P6522), cell dimensions a = b = 54.7 A?, c ~ 185 A?, γ = 120 °, with one subunit (molecular weight 14,000) in the asymmetric unit.  相似文献   

9.
6-(p-Hydroxyphenylhydrazino)-uracil is an antimicrobial agent that selectively blocks replicative DNA synthesis in Bacillus subtilis by inhibiting DNA polymerase III. The drug crystallizes as a monoclinic monohydrate, space group C2c, with a = 23.920(6) Å, b = 5.587(3) Å, c = 17.466(5) Å, β = 101.45(8) °, and eight hydrated molecules per cell. Three-dimensional X-ray diffraction data were collected. The structure was solved by Patterson methods and refined to an R value of 6.8% for the 1651 data. The geometry of the uracil ring is unusual. The bond distances suggest that a resonance form involving a positively charged hydrazino nitrogen and a negatively charged carbonyl oxygen, O(4), makes a large contribution to the valence bond structure of this compound. The exocyclic C(6)N bond is short (1.335 Å), the C(6)C(5) bond distance is 1.371 Å, which is longer than in uracil, and the C(5)C(4) distance (1.396 Å) is short. The uracil ring, the linked hydrazino nitrogen, and the hydrogen on this nitrogen are in the same plane. Each uracil group is hydrogen bonded to a nearly coplanar uracil across a center of symmetry. The water molecule is also near the plane of these paired bases and forms a hydrogen bond with the uracil-linked hydrazino NH group. This paired base arrangement and the restricted rotation about the exocyclic C(6)N link that constrains the hydrazino NH group to lie near the uracil plane suggest a model for the interaction of the drug with template-primer DNA. The drug acts when cytosine is the base to be copied in the template strand, and the drug is competitive with dGTP. Both cytosine and guanine can be accommodated with little distortion of the crystal structure geometry in a manner compatible with the known geometry of DNA. The structural and biochemical aspects of the model for drug action are discussed.  相似文献   

10.
The orthorhombic crystals of l-asparaginase from Escherichia coli A-1-3 KY3598 were characterized by the X-ray diffraction method as belonging to the space group P21221 with unit cell dimensions a = 116.7 A?, b = 62.9 A? and c = 86.6 A?. The crystals contain one half of the tetrameric enzyme molecule per asymmetric unit, the smallest so far reported for this enzyme. Preliminary analysis of the Patterson map indicated that the molecule had at least pseudo 222 symmetry and established the position of the centers of the molecules in the unit cell.  相似文献   

11.
A complex between the complementary hexanucleotides ribo-C-A-A-A-A-G and deoxyribo-C-T-T-T-T-G has been crystallized. The space group was determined to be P21 with unit cell dimensions a = 26.9 A?, b = 50.9 A?, c = 62.0 A?; α = γ = 90 °, β = 108 °. The crystals contain both the ribo- and the deoxyribo-hexanucleotide strands in a ratio of approximately 1:1. Each asymmetric unit contains the equivalent of four hybrid molecules.  相似文献   

12.
Erysimum latent virus, a tymovirus, contains 180 protein subunits arranged in a T = 3 icosahedral surface lattice. A cubic crystal form (with space group P213 and a = 414 A?) and a monoclinic form (space group B2, a = 442 A?, b = 422 A?, c = 387 A?, γ = 95 °) have been observed. The asymmetric units of the two crystal forms contain one-third and one whole virus particle, respectively. Two possible packing arrangements of the virus particles in the monoclinic unit cell have been deduced from the low-angle diffraction patterns. X-ray diffraction data from the monoclinic crystals extend to at least 3·7 Å resolution.  相似文献   

13.
Poliovirus contains 60 copies each of four coat protein subunits arranged on a T = 1 icosahedral surface. Crystals of the Mahoney and the Sabin strains of the type I serotype of polio have been obtained. Crystals of the Mahoney strain belong to the orthorhombic space group P21212 with a = 324 A?, b = 359 A?, c = 381 A?, contain 12 virus particle in the asymmetric unit, and diffract to at least 2.5 Å resolution. The crystals are apparently identical to those characterized by Finch & Klug (1959). Collection of three-dimensional X-ray diffraction data to 2.9 Å resolution is in progress.  相似文献   

14.
Crystals of baboon α-lactalbumin suitable for structure analysis at high resolution have been obtained. They have cell dimensions a = 35.5 A?, b = 69.1 A?, c = 46.1 A?, space group P21212 and contain one molecule of α-lactalbumin per asymmetric unit.  相似文献   

15.
Crystals of human plasma retinol-binding protein have been obtained from 4.5 m-NaCl buffered at pH 6.8 with 20 mm-cacodylate. The crystals are trigonal with space group R3 and unit cell dimensions, referred to the hexagonal system. a = b = 104.2 A? and c = 74.5 A?. The crystals diffract to a resolution of 2.0 Å.  相似文献   

16.
The mitochondrial isoenzyme of aspartate aminotransferase (E.C. 2.6.1.1) has been isolated from chicken heart in an electrophoretically and immunologically homogeneous form. Large, well-diffracting single crystals of this enzyme, a dimeric molecule with a molecular weight of 90,000, have been grown by vapour phase diffusion against polyethylene glycol solutions. The crystals belong to space group P1. The unit cell, with the dimensions a = 55.6 A?, 6 = 58.7 A?, c = 76.0 A?, α = 85.3 °, β = 109.2 °, γ = 115.6 °, contains a single dimer. The diffraction pattern extends to at least 2.1 Å resolution.  相似文献   

17.
Crystals of crambin, a plant seed protein of molecular weight 5000, diffract X-rays strongly to the interplanar spacing limit of 0.88 Å. These diffraction data should allow a definition of atomic structure that is on a par with that typically obtained from crystals of small organic molecules. The crystals are in space group P21 and have unit cell dimensions a = 41.1 A?, b = 18.7 A?, c = 22·7 A?, and β = 90.6 °. The asymmetric unit contains one protein molecule.  相似文献   

18.
Glutathione peroxidase prepared from bovine erythrocytes yields small, but well-ordered plate-like crystals. X-ray investigation shows them to belong to monoclinic space group C2. Unit cell dimensions are: a = 90.4 A?, b = 109.5 A?, c = 58.6 A?, β = 99 ° ± 15 min. The crystal density is ?c = 1.36 ± 0.02 g.cm?3. Consequently, the asymmetric unit of the crystal cell is occupied by one tetrameric molecule of Mr 84,000. Matthew's (1968) parameter ΓM is calculated to be 1.71 Å3/dalton.  相似文献   

19.
Most of the amino groups of horse liver alcohol dehydrogenase were isonicotinimidylated with an imidoester. The enzyme activity increased about 17-fold. The modified protein crystallized during dialysis against buffers of low ionic strength in the monoclinic space group C2 with unit cell dimensions: a = 177.8 A?, b = 61.2 A?, c = 56.5 A? and β = 104.0 °. The crystals appear to be suitable for detailed X-ray structure analysis.  相似文献   

20.
Binding of a simian virus 40 T antigen-related protein to DNA   总被引:90,自引:0,他引:90  
Crystals of the periplasmic galactose-binding protein of Salmonella typhimurium have been subjected to X-ray analysis. The crystals grow as elongated rectangular prisms, with the symmetry of space group C2. Unit cell dimensions are a = 119·7 A?, b = 37·2 A?, c = 80·1 A?, and β = 123·4. There is one protein molecule of molecular weight 33,000 per asymmetric unit.  相似文献   

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