Spermidine acetyltransferase (SAT) from E. coli catalyses the transfer of acetyl groups from acetyl-CoA to spermidine. SAT was crystallized and the crystals contained four molecules in the asymmetric unit.
The spermidine acetyltransferase (SAT) from Escherichia coli catalyses the transfer of acetyl groups from acetyl-CoA to spermidine. SAT has been expressed and purified from E. coli. SAT was crystallized by the sitting-drop vapour-diffusion method to obtain a more detailed insight into the molecular mechanism. Preliminary X-ray diffraction studies revealed that the crystals diffracted to 2.5 Å resolution and belonged to the cubic space group P23, with unit-cell parameters a = b = c = 148.7 Å. They contained four molecules per asymmetric unit.
spermidine acetyltransferase; Escherichia coli
The bacterial cell-division protein FtsA from methicillin-resistant S. aureus was crystallized and X-ray diffraction data were collected to a resolution of 2.3 Å.
FtsA from methicillin-resistant Staphylococcus aureus (MRSA) was cloned, overexpressed and purified. The protein was crystallized using the sitting-drop vapour-diffusion technique. A cocrystal with β-γ-imidoadenosine 5′-phosphate (AMPPNP; a nonhydrolysable ATP analogue) was grown using PEG 3350 as a precipitant at 293 K. X-ray diffraction data were collected to a resolution of 2.3 Å at 100 K. The crystal belonged to the monoclinic space group P21, with unit-cell parameters a = 75.31, b = 102.78, c = 105.90 Å, β = 96.54°. The calculated Matthews coefficient suggested that the asymmetric unit contained three or four monomers.
bacterial divisome; methicillin-resistant Staphylococcus aureus; FtsA
The crystal structure of the archaeal peroxiredoxin from P. horikoshii was determined at a resolution of 2.25 Å and compared with that of a homologous protein from A. pernix.
The crystal structure of peroxiredoxin from the anaerobic hyperthermophilic archaeon Pyrococcus horikoshii (PhPrx) was determined at a resolution of 2.25 Å. The overall structure was a ring-type decamer consisting of five homodimers. Citrate, which was included in the crystallization conditions, was bound to the peroxidatic cysteine of the active site, with two O atoms of the carboxyl group mimicking those of the substrate hydrogen peroxide. PhPrx lacked the C-terminal tail that forms a 32-residue extension of the protein in the homologous peroxiredoxin from Aeropyrum pernix (ApPrx).
peroxiredoxins; Pyrococcus horikoshii
Orotate phosphoribosyltransferase from Plasmodium falciparum produced in Escherichia coli was crystallized by the sitting-drop vapour-diffusion method in complex with OA and PRPP in the presence of Mg2+.
Orotate phosphoribosyltransferase (OPRT) catalyzes the Mg2+-dependent condensation of orotic acid (OA) with 5-α-d-phosphorylribose 1-diphosphate (PRPP) to yield diphosphate (PPi) and the nucleotide orotidine 5′-monophosphate. OPRT from Plasmodium falciparum produced in Escherichia coli was crystallized by the sitting-drop vapour-diffusion method in complex with OA and PRPP in the presence of Mg2+. The crystal exhibited tetragonal symmetry, belonging to space group P41 or P43, with unit-cell parameters a = b = 49.15, c = 226.94 Å. X-ray diffraction data were collected to 2.5 Å resolution at 100 K using a synchrotron-radiation source.
orotate phosphoribosyltransferase; Plasmodium falciparum
Aldo-keto reductase 1B3 (AKR1B3) produced in Escherichia coli has been crystallized in complex with NADPH by the sitting-drop vapour-diffusion method.
Aldo-keto reductase 1B3 (AKR1B3) catalyzes the NADPH-dependent reduction of prostaglandin H2 (PGH2), which is a common intermediate of various prostanoids, to form PGF2α. AKR1B3 also reduces PGH2 to PGD2 in the absence of NADPH. AKR1B3 produced in Escherichia coli was crystallized in complex with NADPH by the sitting-drop vapour-diffusion method. The crystal was tetragonal, belonging to space group P41212 or P43212, with unit-cell parameters a = b = 107.62, c = 120.76 Å. X-ray diffraction data were collected to 2.4 Å resolution at 100 K using a synchrotron-radiation source.
aldo-keto reductases; AKR1B3; prostaglandin F2α synthase
Crystals of the helicase domain from a tomato mosaic virus replication protein obtained using the hanging-drop vapour-diffusion method at 285 K diffracted X-rays to 2.05 Å resolution. They belonged to the orthorhombic space group P212121, with unit-cell parameters a = 85.8, b = 128.3, c = 40.7 Å.
Tomato mosaic virus belongs to the genus Tobamovirus in the alphavirus-like superfamily of positive-strand RNA viruses. The alphavirus-like superfamily includes many plant and animal viruses of agronomical and clinical importance. These viruses encode replication-associated proteins that contain a putative superfamily 1 helicase domain. No three-dimensional structures for this domain have been determined to date. Here, the crystallization and preliminary X-ray diffraction analysis of the 130K helicase domain are reported. Diffraction data were collected and processed to 2.05 and 1.75 Å resolution from native and selenomethionine-labelled crystals, respectively. The crystals belonged to the orthorhombic space group P212121, with unit-cell parameters a = 85.8, b = 128.3, c = 40.7 Å.
tomato mosaic virus; replicase protein; helicase domain
The genomes of the Tomato mosaic virus and many other plant and animal positive-strand RNA viruses of agronomic and medical importance encode superfamily 1 helicases. Although helicases play important roles in viral replication, the crystal structures of viral superfamily 1 helicases have not been determined. Here, we report the crystal structure of a fragment (S666 to Q1116) of the replication protein from Tomato mosaic virus. The structure reveals a novel N-terminal domain tightly associated with a helicase core. The helicase core contains two RecA-like α/β domains without any of the accessory domain insertions that are found in other superfamily 1 helicases. The N-terminal domain contains a flexible loop, a long α-helix, and an antiparallel six-stranded β-sheet. On the basis of the structure, we constructed deletion mutants of the S666-to-Q1116 fragment and performed split-ubiquitin-based interaction assays in Saccharomyces cerevisiae with TOM1 and ARL8, host proteins that are essential for tomato mosaic virus RNA replication. The results suggested that both TOM1 and ARL8 interact with the long α-helix in the N-terminal domain and that TOM1 also interacts with the helicase core. Prediction of secondary structures in other viral superfamily 1 helicases and comparison of those structures with the S666-to-Q1116 structure suggested that these helicases have a similar fold. Our results provide a structural basis of viral superfamily 1 helicases.
Micro-scale, non-invasive, three-dimensional cross-sectional imaging of protein crystals was successfully accomplished using ultra-high resolution optical coherence tomography (UHR-OCT) with low noise, Gaussian like supercontinuum. This technique facilitated visualization of protein crystals even those in medium that also contained substantial amounts of precipitates. We found the enhancement of the scattered signal from protein crystal by inclusion of agarose gel in the crystallization medium. Crystals of a protein and a salt in the same sample when visualized by UHR-OCT showed distinct physical characteristics, suggesting that protein and salt crystals may, in general, be distinguishable by UHR-OCT. UHR-OCT is a nondestructive and rapid method, which should therefore find use in automated systems designed to visualize crystals.
(110.4500) Optical coherence tomography; (170.3880) Medical and biological imaging
In the biosynthesis of the clinically important antibiotic erythromycin D, the glycosyltransferase (GT) EryCIII, in concert with its partner EryCII, attaches a nucleotide-activated sugar to the macrolide scaffold with high specificity. To understand the role of EryCII, we have determined the crystal structure of the EryCIII·EryCII complex at 3.1 Å resolution. The structure reveals a heterotetramer with a distinctive, elongated quaternary organization. The EryCIII subunits form an extensive self-complementary dimer interface at the center of the complex, and the EryCII subunits lie on the periphery. EryCII binds in the vicinity of the putative macrolide binding site of EryCIII but does not make direct interactions with this site. Our biophysical and enzymatic data support a model in which EryCII stabilizes EryCIII and also functions as an allosteric activator of the GT.
► First structure of macrolide GT and auxiliary protein. ► New system for the expression of EryCIII and EryCII. ► Auxiliary protein (EryCII) stabilizes GT (EryCIII). ► EryCII has cytochrome P450 fold but possesses an additional N-terminal helix.
GT, glycosyltransferase; LC-MS, liquid chromatography combined with mass spectrometry; Se-Met, selenomethionine; PDB, Protein Data Bank; glycosyltransferase; antibiotic synthesis; crystal structure; cytochrome P450
Crystals of the 45.1 kDa functional form of 2,3-diketo-5-methylthiopentyl-1-phosphate enolase from B. subtilis diffracted to 2.30 Å resolution.
2,3-Diketo-5-methylthiopentyl-1-phosphate enolase (DK-MTP-1P enolase) from Bacillus subtilis was crystallized using the hanging-drop vapour-diffusion method. Crystals grew using PEG 3350 as the precipitant at 293 K. The crystals diffracted to 2.3 Å resolution at 100 K using synchrotron radiation and were found to belong to the monoclinic space group P21, with unit-cell parameters a = 79.3, b = 91.5, c = 107.0 Å, β = 90.8°. The asymmetric unit contained four molecules of DK-MTP-1P enolase, with a V
M value of 2.2 Å3 Da−1 and a solvent content of 43%.
methionine-salvage pathway; Bacillus subtilis; RuBisCO; RuBisCO-like proteins; 2,3-diketo-5-methylthiopentyl-1-phosphate enolase
The plasma-membrane Na+/Ca2+ exchanger (NCX) regulates intracellular Ca2+ levels in cardiac myocytes. Two Ca2+-binding domains (CBD1 and CBD2) exist in the large cytosolic loop of NCX. Recombinant CBD1 (NCX1 372–508) with a molecular weight of 16 kDa has been crystallized by the sitting-drop vapour-diffusion method at 293 K.
The plasma-membrane Na+/Ca2+ exchanger (NCX) regulates intracellular Ca2+ levels in cardiac myocytes. Two Ca2+-binding domains (CBD1 and CBD2) exist in the large cytosolic loop of NCX. The binding of Ca2+ to CBD1 results in conformational changes that stimulate exchange to exclude Ca2+ ions, whereas CBD2 maintains the structure, suggesting that CBD1 is the primary Ca2+-sensor. In order to clarify the structural scaffold for the Ca2+-induced conformational transition of CBD1 at the atomic level, X-ray structural analysis of its Ca2+-free form was attempted; the structure of the Ca2+-bound form is already available. Recombinant CBD1 (NCX1 372–508) with a molecular weight of 16 kDa was crystallized by the sitting-drop vapour-diffusion method at 293 K. The crystals belonged to the hexagonal space group P6222 or P6422, with unit-cell parameters a = b = 56.99, c = 153.86 Å, β = 120°, and contained one molecule per asymmetric unit (V
M = 2.25 Å3 Da−1) with a solvent content of about 55% (V
S = 45.57%). Diffraction data were collected within the resolution range 27.72–3.00 Å using an R-AXIS detector and gave a data set with an overall R
merge of 10.8% and a completeness of 92.8%.
Na+/Ca2+ exchanger; Ca2+-sensors
The structures of old yellow enzyme from Trypanosoma cruzi which produces prostaglandin F2α from PGH2 have been determined in the presence or absence of menadione.
Old yellow enzyme (OYE) is an NADPH oxidoreductase which contains flavin mononucleotide as prosthetic group. The X-ray structures of OYE from Trypanosoma cruzi (TcOYE) which produces prostaglandin (PG) F2α from PGH2 have been determined in the presence or absence of menadione. The binding motif of menadione, known as one of the inhibitors for TcOYE, should accelerate the structure-based development of novel anti-chagasic drugs that inhibit PGF2α production specifically.
X-ray structure; inhibitor complex; prostaglandin synthase
Three crystallization methods, including crystallization in the presence of a semi-solid agarose gel, top-seeded solution growth (TSSG) and a large-scale hanging-drop method, have previously been presented. In this study, crystallization has been further evaluated in the presence of a semi-solid agarose gel by crystallizing additional proteins. A novel crystallization method combining TSSG and the large-scale hanging-drop method has also been developed.
Three crystallization methods for growing large high-quality protein crystals, i.e. crystallization in the presence of a semi-solid agarose gel, top-seeded solution growth (TSSG) and a large-scale hanging-drop method, have previously been presented. In this study the effectiveness of crystallization in the presence of a semi-solid agarose gel has been further evaluated by crystallizing additional proteins in the presence of 2.0% (w/v) agarose gel, resulting in complete gelification with high mechanical strength. In TSSG the seed crystals are hung by a seed holder protruding from the top of the growth vessel to prevent polycrystallization. In the large-scale hanging-drop method, a cut pipette tip was used to maintain large-scale droplets consisting of protein–precipitant solution. Here a novel crystallization method that combines TSSG and the large-scale hanging-drop method is reported. A large and single crystal of lysozyme was obtained by this method.
semi-solid agarose gels; top-seeded solution growth; large-scale hanging-drop method; X-ray crystallography; neutron crystallography
In order to determine the protonation states of the residues within the active site of an HIV-1 protease–inhibitor complex, a crystal of HIV-1 protease complexed with inhibitor (KNI-272) was grown to a size of 1.4 mm3 for neutron diffraction study. The crystal diffracted to 2.3 Å resolution with sufficient quality for further structure determination.
This paper reports the crystallization and preliminary neutron diffraction measurements of HIV-1 protease, a potential target for anti-HIV therapy, complexed with an inhibitor (KNI-272). The aim of this neutron diffraction study is to obtain structural information about the H atoms and to determine the protonation states of the residues within the active site. The crystal was grown to a size of 1.4 mm3 by repeated macroseeding and a slow-cooling method using a two-liquid system. Neutron diffraction data were collected at room temperature using a BIX-4 diffractometer at the JRR-3 research reactor of the Japan Atomic Energy Agency (JAEA). The data set was integrated and scaled to 2.3 Å resolution in space group P21212, with unit-cell parameters a = 59.5, b = 87.4, c = 46.8 Å.
HIV-1 protease; inhibitors; neutron diffraction
An RNA aptamer in complex with the human IgG Fc fragment have been crystallized. The stirring technique with a rotary shaker was used to improve the crystals and to ensure that they were of high quality and single, resulting in crystals that diffracted to 2.2 Å resolution.
Aptamers, which are folded DNA or RNA molecules, bind to target molecules with high affinity and specificity. An RNA aptamer specific for the Fc fragment of human immunoglobulin G (IgG) has recently been identified and it has been demonstrated that an optimized 24-nucleotide RNA aptamer binds to the Fc fragment of human IgG and not to other species. In order to clarify the structural basis of the high specificity of the RNA aptamer, it was crystallized in complex with the Fc fragment of human IgG1. Preliminary X-ray diffraction studies revealed that the crystals belonged to the orthorhombic space group P21212, with unit-cell parameters a = 83.7, b = 107.2, c = 79.0 Å. A data set has been collected to 2.2 Å resolution.
RNA aptamers; Fc fragments; immunoglobulin G
Aptamers are short single-stranded nucleic acids with high affinity to target molecules and are applicable to therapeutics and diagnostics. Regardless of an increasing number of reported aptamers, the structural basis of the interaction of RNA aptamer with proteins is poorly understood. Here, we determined the 2.15 Å crystal structure of the Fc fragment of human IgG1 (hFc1) complexed with an anti-Fc RNA aptamer. The aptamer adopts a characteristic structure fit to hFc1 that is stabilized by a calcium ion, and the binding activity of the aptamer can be controlled many times by calcium chelation and addition. Importantly, the aptamer–hFc1 interaction involves mainly van der Waals contacts and hydrogen bonds rather than electrostatic forces, in contrast to other known aptamer–protein complexes. Moreover, the aptamer–hFc1 interaction involves human IgG-specific amino acids, rendering the aptamer specific to human IgGs, and not crossreactive to other species IgGs. Hence, the aptamer is a potent alternative for protein A affinity purification of Fc-fusion proteins and therapeutic antibodies. These results demonstrate, from a structural viewpoint, that conformational plasticity and selectivity of an RNA aptamer is achieved by multiple interactions other than electrostatic forces, which is applicable to many protein targets of low or no affinity to nucleic acids.
Old yellow enzyme from Trypanosoma cruzi, has been crystallized using the hanging-drop vapour-diffusion method.
Old yellow enzyme (OYE) is an NADPH oxidoreductase that contains a flavin mononucleotide as a prosthetic group. The OYE from Trypanosoma cruzi, which produces prostaglandin F2α, a potent mediator of various physiological and pathological processes, from prostaglandin H2. The protein was recombinantly expressed and purified from Escherichia coli and was crystallized using the hanging-drop vapour-diffusion method. The crystal belongs to the monoclinic space group P21, with unit-cell parameters a = 56.3, b = 78.8, c = 78.8 Å, β = 93.4° and two molecules per asymmetric unit. The crystals were suitable for X-ray crystallographic studies and diffracted to 1.70 Å resolution. A Patterson search method is in progress using the structure of OYE from Pseudomonas putida as a starting model.
old yellow enzyme; NADPH oxidoreductases
A family I.3 lipase from Pseudomonas sp. MIS38 was secreted from Escherichia coli cells to the external medium, purified and crystallized and preliminary crystallographic studies were performed.
A family I.3 lipase from Pseudomonas sp. MIS38 was secreted from Escherichia coli cells to the external medium, purified and crystallized and preliminary crystallographic studies were performed. The crystal was grown at 277 K by the hanging-drop vapour-diffusion method. Native X-ray diffraction data were collected to 1.7 Å resolution using synchrotron radiation at station BL38B1, SPring-8. The crystal belongs to space group P21, with unit-cell parameters a = 48.79, b = 84.06, c = 87.04 Å. Assuming the presence of one molecule per asymmetric unit, the Matthews coefficient V
M was calculated to be 2.73 Å3 Da−1 and the solvent content was 55%.
family I.3 lipases
Glycerol kinase from the hyperthermophilic archaeon Thermococcus kodakaraensis was crystallized and preliminary crystallographic studies of the crystals were performed.
Glycerol kinase from the hyperthermophilic archaeon Thermococcus kodakaraensis was crystallized and preliminary crystallographic studies of the crystals were performed. Crystals were grown at 293 K by the sitting-drop vapour-diffusion method. Native X-ray diffraction data were collected to 2.4 Å resolution using synchrotron radiation at station BL44XU of SPring-8. The crystal belongs to the rhombohedral space group R3, with unit-cell parameters a = b = 217.48, c = 66.48 Å. Assuming the presence of two molecules in the asymmetric unit, the V
M value was 2.7 Å3 Da−1 and the solvent content was 54.1%. The protein was also cocrystallized with substrates and diffraction data were collected to 2.7 Å resolution.
glycerol kinase; Thermococcus kodakaraensis; thermostability
Crystallization of and preliminary crystallographic studies on an active-site mutant of pro-Tk-subtilisin from the hyperthermophilic archaeon T. kodakaraensis were performed.
Crystallization of and preliminary crystallographic studies on an active-site mutant of pro-Tk-subtilisin from the hyperthermophilic archaeon Thermococcus kodakaraensis were performed. The crystal was grown at 277 K by the sitting-drop vapour-diffusion method. Native X-ray diffraction data were collected to 2.3 Å resolution using synchrotron radiation from station BL41XU at SPring-8. The crystal belongs to the orthorhombic space group I222, with unit-cell parameters a = 92.69, b = 121.78, c = 77.53 Å. Assuming the presence of one molecule per asymmetric unit, the Matthews coefficient V
M was calculated to be 2.6 Å3 Da−1 and the solvent content was 53.1%.
pro-Tk-subtilisin; Thermococcus kodakaraensis
Orotidine 5′-monophosphate decarboxylase of human malaria parasite P. falciparum was crystallized by the seeding method in a hanging drop using PEG 3000 as a precipitant. A complete set of diffraction data from a native crystal was collected to 2.7 Å resolution at 100 K using synchrotron radiation.
Orotidine 5′-monophosphate (OMP) decarboxylase (OMPDC; EC 220.127.116.11) catalyzes the final step in the de novo synthesis of uridine 5′-monophosphate (UMP) and defects in the enzyme are lethal in the malaria parasite Plasmodium falciparum. Active recombinant P. falciparum OMPDC (PfOMPDC) was crystallized by the seeding method in a hanging drop using PEG 3000 as a precipitant. A complete set of diffraction data from a native crystal was collected to 2.7 Å resolution at 100 K using synchrotron radiation at the Swiss Light Source. The crystal exhibits trigonal symmetry (space group R3), with hexagonal unit-cell parameters a = b = 201.81, c = 44.03 Å. With a dimer in the asymmetric unit, the solvent content is 46% (V
M = 2.3 Å3 Da−1).
orotidine 5′-monophosphate decarboxylase; Plasmodium falciparum
The RNA thiouridylase MnmA in complex with tRNA was crystallized with and without ATP in three different crystal forms, which may reflect distinct sulfuration-reaction stages.
MnmA catalyzes a sulfuration reaction to synthesize 2-thiouridine at the wobble positions of tRNAGlu, tRNAGln and tRNALys in Escherichia coli. The binary complex of MnmA and tRNAGlu was crystallized in two different crystal forms: forms I and II. Cocrystallization of MnmA–tRNAGlu with ATP yielded form III crystals. The three crystal forms diffracted to 3.1, 3.4 and 3.4 Å resolution, respectively, using synchrotron radiation at SPring-8. These crystals belong to space groups C2, I212121 and C2, with unit-cell parameters a = 225.4, b = 175.8, c = 53.0 Å, β = 101.6°, a = 101.5, b = 108.0, c = 211.2 Å and a = 238.1, b = 102.1, c = 108.2 Å, β = 117.0°, respectively. The asymmetric units of these crystals are expected to contain two, one and two MnmA–tRNAGlu complexes, respectively.
MnmA; tRNA; ATP; Escherichia coli
SecDF is a multi-path membrane protein required for efficient protein translocation and integration via translocon. Purification and crystallization of T. thermophilus SecDF have been achieved by exploiting unique crystallization techniques that allowed the collection of a 3.74 Å data set.
Thermus thermophilus has a multi-path membrane protein, TSecDF, as a single-chain homologue of Escherichia coli SecD and SecF, which form a translocon-associated complex required for efficient preprotein translocation and membrane-protein integration. Here, the cloning, expression in E. coli, purification and crystallization of TSecDF are reported. Overproduced TSecDF was solubilized with dodecylmaltoside, chromatographically purified and crystallized by vapour diffusion in the presence of polyethylene glycol. The crystals yielded a maximum resolution of 4.2 Å upon X-ray irradiation, revealing that they belonged to space group P43212. Attempts were made to improve the diffraction quality of the crystals by combinations of micro-stirring, laser-light irradiation and dehydration, which led to the eventual collection of complete data sets at 3.74 Å resolution and preliminary success in the single-wavelength anomalous dispersion analysis. These results provide information that is essential for the determination of the three-dimensional structure of this important membrane component of the protein-translocation machinery.
SecDF; membrane proteins; protein translocation; dehydration
Crystals of the 39 kDa functional form of methylthioribose-1-phosphate isomerase from B. subtilis diffracted to 2.50 Å.
Methylthioribose-1-phosphate isomerase (MtnA) from Bacillus subtilis, the first enzyme in the downstream section of the methionine-salvage pathway, was crystallized using the sitting-drop vapour-diffusion method. Crystals grew using ammonium sulfate as the precipitant at 293 K. They diffracted to 2.5 Å at 100 K using synchrotron radiation and were found to belong to the tetragonal space group P41, with unit-cell parameters a = b = 69.2, c = 154.7 Å. The asymmetric unit contains two molecules of MtnA, with a V
M value of 2.4 Å3 Da−1 and a solvent content of 48%.
methylthioribose-1-phosphate; methylthioribulose-1-phosphate; methylthioadenosine
A human kynurenine aminotransferase II homologue from P. horikoshii OT3 has been overproduced in E. coli, purified, and characterized. Crystals of this protein have been obtained and analyzed by X-ray diffraction.
The Pyrococcus horikoshii OT3 genome contains a gene encoding a human kynurenine aminotransferase II (KAT II) homologue, which consists of 428 amino-acid residues and shows an amino-acid sequence identity of 30% to human KAT II. This gene was overexpressed in Escherichia coli and the recombinant protein (Ph-KAT II) was purified. Gel-filtration chromatography showed that Ph-KAT II exists as a homodimer. Ph-KAT II exhibited enzymatic activity that catalyzes the transamination of l-kynurenine to produce kynurenic acid. Crystals of Ph-KAT II were grown using the sitting-drop vapour-diffusion method and native X-ray diffraction data were collected to 2.2 Å resolution using synchrotron radiation from station BL44XU at SPring-8. The crystals belong to the centred orthorhombic space group C2221, with unit-cell parameters a = 71.75, b = 86.84, c = 137.30 Å. Assuming one molecule per asymmetric unit, the V
M value was 2.19 Å3 Da−1 and the solvent content was 43.3%.
kynurenine aminotransferase II; Pyrococcus horikoshii OT3