The quaternary structure of a unique phycobiliprotein: B-phycoerythrin from Porphyridium cruentum

B-phycoerythrin, from the unicellular red alga Porphyridium cruentum, was crystallized in the rhombohedral space group R3 with a=111.0Å and α=116.8° or A=B=189.1Å and C=60.1Å and γ=120°. Density measurements on the crystals indicate that the hexagonal unit cell can acconmodate three cylindrical molecules, 109Å in diameter and 60Å in height, each of approximately 275,000 daltons. The crystallographic symmetry of the unit cell requires at least 3-fold symmetry for the particle. However, the particle stoichiometry has been reported as (αβ)₆γ and this composition is also supported by SDS gel electrophoresis on the crystalline protein. These results are discussed in light of preliminary model calculations on the quaternary structure of B-phycoerythrin.     

Differential MicroRNAs Expression in Serum of Patients with Lung Cancer, Pulmonary Tuberculosis, and Pneumonia

MicroRNAs (miRNAs) play critical regulatory roles in the physiological and pathological processes. The high stability of miRNAs in human serum represents attractive novel diagnostic biomarkers of clinical conditions. Several studies have shown that aberrant expression of miRNAs in human cancer including lung cancer, but little is known about their effects on some infectious lung diseases such as pulmonary tuberculosis (TB) and pneumonia. In this study, we investigated miRNA expression pattern in serum of Egyptian patients with lung cancer, TB, and pneumonia compared with matched healthy controls. Using microarray-based expression profiling followed by real-time quantitative polymerase chain reaction validation, we compared the levels of a series of circulating miRNAs (miR-21, miR-155, miR-182, and miR-197) in serum from patients with lung cancer (n = 65), pulmonary tuberculosis (n = 29), pneumonia (n = 29), and transudate (n = 16) compared with matched healthy controls (n = 37). MiRNA SNORD68 was the housekeeping endogenous control. We found that the serum levels of miR-21, miR-155, and miR-197 were significantly elevated in the patients with lung cancer and pneumonia whereas miR-182 and miR-197 levels were increased only in patients with lung cancer and TB, respectively, compared with controls. Receiver operating characteristic analysis revealed that miR-182, miR-155, and miR-197 have superior diagnostic potential in discriminating patients with lung cancer, pneumonia, and TB, respectively, from controls. Our results conclude that the differential expression of the four studied miRNAs can be potential non-invasive biomarkers for patients with lung cancer, TB and pneumonia.     

A dinuclear,metal-metal bonded,carboxylato-bridged niobium(III) complex

Nb₂Cl₆(THT)₃, THT=tetrahydrothiophene, reacts with excess tetramethylammonium acetate to give an ionic Nb(III) complex, (NMe₄)[Nb₂Cl₂(THT)(CH₃CO₂)₅]·CH₂Cl₂. The compound has been characterized by NMR, IR, cyclic voltammetry and X-ray crystallography. It crystallizes in an orthorhombic space group P2₁2₁2₁ with a=11.326(3) Å, b=11.857(4) Å, c=24.343(6) Å, V=3269(3) ų and Z=4. The NbNb distance is equal to 2.764(1) Å which together with the diamagnetism of the complex indicates a double metal-metal bond. The acetato ligands coordinate in three different modes: bridging bidentate, chelating and bridging unidentate.     

Enzymatic properties,crystallization, and deduced amino acid sequence of an alkaline endoglucanase from Bacillus circulans

A high-isoelectric-point (pI), alkaline endo-1,4-β-glucanase (Egl-257) of Bacillus circulans KSM-N257 was purified to homogeneity and crystallized. The purified enzyme hydrolyzed carboxymethyl cellulose (CMC) with optima of pH 8.5 and 55 °C. The molecular mass was 43 kDa, and the pI was pH 9.3. The structural gene contained a single open reading frame of 1221 bp, corresponding to 407 amino acids (aa), including a 30-aa signal peptide (377 aa and 41,680 Da for the mature enzyme). Egl-257 hydrolyzed lichenan and showed 76.3% aa identity to a lichenase from B. circulans WL-12 belonging to glycosyl hydrolase family 8 but did not hydrolyze laminarin, curdran, and xylan at all. This indicates that Egl-257 is a true endo-1,4-β-glucanase. However, this enzyme was not active on p-nitrophenyl β-d-cellotrioside and p-nitrophenyl β-d-cellotetraoside. It was crystallized by the hanging-drop vapor-diffusion method with phosphate plus CdCl₂ as precipitant. Pyramid-like crystals were formed, and they diffracted X-rays beyond 2.2 Å resolution. It belongs to the space group P2₁2₁2₁ with unit cell parameters of a=62.5 Å, b=71.7 Å, and c=88.6 Å.     

Purification, crystallization and preliminary crystallographic investigations of selenium-containing phycocyanin from selenium-rich algae (Spirulina platensis)

The selenium-containing phycocyanin from the selenium-rich algae (Spirulina platensis) has been crystallized in two crystal forms by the hanging-drop vapor diffusion techniques. A chromatographic procedure of gel filtration and anion exchange was used for purification. Form I crystal with space group P2₁ and cell parameters a =108.0 Å , b = 117.0 Å , c = 184.0 Å , β = 90.2° and 12(αβ ) units in the asymmetric unit was obtained by using (NH₄)₂SO₄ as precipitant. These crystals diffract up to 2.8 Å . Form II crystal obtained by using PEG4000 as precipitant belongs to space group P63 with unit cell constants a = 155.0 Å , c = 40.3 Å , γ =120.0° and one(αβ ) unit in the asymmetric unit. The crystals diffract beyond 2.9 Å . The possible stacking forms of phycocyanin molecules in the first crystal form were discussed.     

New preparations and molecular structures of cis-MCl2(Ph2PCH2PPh2)2, M = Ru,Os and trans-RuCl2(Ph2PCH2PPh2)2

The title compounds were made by reacting bis(diphenylphosphino)methane (dppm) with reduced solutions of OsCl₆^4? and Ru₂OCl₁₀^4?. The crystal and molecular structures of these compounds have been determined form three-dimensional X-ray study. The cis-isomers crystallize with one CHCl₃ per molecule of the complex. All three compounds crystallize in the monoclinic space group P2₁/n with unit cell dimensions as follows: Cis-OsCl₂(dppm)₂·CHCl₃: a = 13.415(4) Å, b = 22.859(4) Å, c = 16.693(3) Å, β = 105.77(3)°, V = 4926(3) ų, Z = 4. cis-RuCl₂(dppm)₂·CHCl₃: a = 13.442(3) Å, b = 22.833(7) Å, c = 16.750(4) Å, β = 105.53(2)°, V = 4953(3) ų, Z = 4. trans-RuCl₂(dppm)₂: a = 11.368(7) Å, b = 10.656(6) Å, c = 18.832(12) Å; β = 103.90(6)°, V = 2213(7) ų; Z = 2. The structures were refined to R = 0.044 (R_w = 0.055) for cis-OsCl₂(dppm)₂·CHCl₃; R = 0.065 (R_w = 0.079) for cis-RuCl₂(dppm)₂·CHCl₃ and R = 0.028 (R_w = 0.038) for trans-RuCl₂(dppm)₂. The complexes are six coordinate with stable four-membered chelate rings. The PMP angle in the chelate rings is ca. 71° in each case.     

Host plant use by the Heath fritillary butterfly, Melitaea athalia: plant habitat, species and chemistry

We present a study of habitat use, oviposition plant choice, and food plant suitability for the checkerspot butterfly Melitaea athalia Rottemburg (Lepidoptera: Nymphalidae) in Åland, Finland. We found that in Åland, unlike in the mainland of Finland and many parts of its range, M. athalia flies mainly in open meadows. When offered an array of plants in a large (32 × 26 m) field cage, they predominately oviposited upon Veronica chamaedrys L., V. spicata L. and Plantago lanceolata L. (Plantaginaceae), which grow in open meadows. The relative abundance of the butterfly in Åland, and its habitat and host plant use there, may reflect local adaptation to land use practices and geology that maintain clusters of small open meadows with little successional change. At the scale of a plant patch, preferred species were used as frequently in mixed species patches as in mono-specific patches, and more oviposition occurred in open than in grassy patches. All of the host plants used by M. athalia are defended by iridoid glycosides (IGs). However, oviposition choice among species and among individual plants within species was largely independent of IG concentration. This contrast with the more discerning congener, M. cinxia, supports the idea that host discrimination decreases with increasing host range. Finally, although the adult butterflies chose specific plant species for oviposition, as larvae they performed well on twelve out of thirteen species of plants, including both known hosts and related novel plants that occur in Åland, indicating a much wider range of larval food plant species than adult oviposition species.     

Synthesis,properties and structure of hexaaquo-tris(N,N-dimethylformamide)-lanthanide trifluoromethanesulfonates

The compounds of general formula [Ln(DMF)₃- (H₂O)₆](CF₃SO₃)₃ (Ln = LaEu, Tb, Dy) were synthesized and characterized by microanalysis, conductance measurements, IR absorption (Nd³⁺) and emission (Eu³⁺) spectra. The crystal structure of the neodymium compound was determined by X-ray diffraction techniques. The compound crystallizes in the triclinic system, space group P1, a = 8.589(4), b = 11.222(2), c = 12.271(2) Å, α = 56.83(2), β = 62.13(2), γ = 75.14(2)°, V = 875.2 ų, M = 918.4, Z = 1, D_c = 1.73 g cm⁻³, λ(Mo Kα) = 0.71073 Å, μ = 1.65 mm⁻¹, F(000) = 456, R = 0.056, R_w = 0.057, for 2979 independent reflections with I > 3σ(I). Nd³⁺ is coordinated to the oxygen atoms of six independent water molecules at a mean distance NdO = 2.52(1) Å, and to the oxygen atoms of three independent DMF groups at a mean distance NdO = 2.40(2) Å. The coordination polyhedron is a tricapped trigonal prism of point symmetry C_3v.     

Ultrastructure of thylakoid membranes in C. reinhardtii: Evidence for variations in the partition coefficient of the light-harvesting complex-containing particles upon membrane fracture

The ultrastructure of the thylakoid membranes of Chlamydomonas reinhardtii was investigated using cell cultures grown under light intensities of 200 and 4000 lx, respectively. A significant difference in the size distribution of the exoplasmic fracture face (EF) particles appears upon Mg²⁺ treatment of broken cell preparations from the two light growth conditions. Particles larger than 150 Å are seen at 4000 lx only. However neither the absorption spectra of chlorophyll at 77 °K, nor the chlorophyll a/chlorophyll b ratios differ in the two cell batches. In addition, the polypeptide composition of the thylakoid membranes and the Mg²⁺ effect (spillover) on the photochemical rate of Photosystem II are the same in both conditions. We conclude that the partition coefficient between the two fracture faces of light-harvesting complex-containing particles is variable. It depends on Mg²⁺ ion concentration in the incubating medium of the membranes and on the light growth conditions of the cell cultures. Our results suggest that 60- to 80-Å protoplasmic fracture face (PF) particles containing the light-harvesting complexes can aggregate either in larger PF particles (100–120 Å) or in EF particles larger than 120 Å which also contain the Photosystem II centers. That some light-harvesting complexes are located on the PF faces is confirmed by the analysis of the BF4 mutant of C. reinhardtii lacking in chlorophyll-protein complex II. The PF faces of the BF4 thylakoids display a reduced number of particles as compared to that in the wild type.     

Uranyl complexes of acetamidoxime and benzamidoxime. Preparation,characterization, and crystal structure

The uranyl complexes [UO₂(acetamidoxime)₄](NO₃)₂ (1) and [UO₂(benzamidoxime)₄](NO)₃)₂·χS (S = nitromethane or 1,2-dichloroethane, χ < 1) (2) were prepared by the reaction of uranyl nitrate with the corresponding amidoxime in ethanolic solution, and characterized by thermal analysis and infrared spectroscopy. The crystal structures of the acetamidoxime complex and the 1,2-dichloroethane-containing benzamidoxime complex (2a) were determined by single crystal X-ray diffraction measurements and refined R₁ = 0.018 and 0.070, respectively. 1 crystallizes in the monoclinic space group I2/c with a = 14.929(3), b = 8.946(2), c = 16.790(4) Å, β = 96.01(2)° and Z = 4, whereas crystals of 2a are triclinic, space group P $\text{1}$ with a = 9.890(4), b = 14.226(6), c = 15.227(6) Å, α = 75.76(3), β = 87.13(3), γ = 81.22(3)° and Z = 2. In both complexes the linear uranyl group is equatorially surrounded by four oxygen atoms of monodentate amidoxime ligands, the mean bond lengths in 1 and 2a being: UO_uranyl = 1.775 and 1.78 Å and UO_amidoxime = 2.308 and 2.26 Å, respectively. In accordance with infrared spectroscopic results the nitrate ions are not coordinated to uranium, but interact with the ligand molecules via hydrogen bonds.     

The crystal and molecular structures of dichloro [N,O-(D,L)-diaminopropionic acid] platinum(II) and Dichloro [N,O-(L)-lysine] platinum(II) monohydrate

K₂PtCl₄ reacts with L-lysine and with D,L-diaminiopropionic acid (Dap) forming the neutral complexes [PtCl₂(N,O-Lys)]·H₂0 (1) and [PtCl₂(N,O-Dap)], (2) respectively.Compound 1 is monoclinic, space group P2₁ with a = 11.262(3), b = 11.041(2), c = 9.690(2) Å, β = 102.07(5)°, V = 1178(1) ų and Z = 4. Compound 2 is monoclinic, space group P2₁/n with a = 8.777(1), b = 10.615(2), c = 7.947(1) Å, β = 94.98(3)°, V = 738(1) ų and Z = 4. In both compounds, the zwitterionic ligands form an N,O-five membered chelate with the platinum atom. Structures 1 and 2 were refined to R values of 3.3% and 6.3% respectively.     

The crystal and molecular structures of dioxo mo(VI) complexes of tripodal,tetradentate N,S-donor ligands

The crystal and molecular structures of the complexes MoO₂((SCH₂CH₂)₂NCH₂CH₂SCH₃), I and MoO₂((SCH₂CH₂)₂NCH₂CH₂N(CH₃)₂), II, have been determined from X-ray intensity data collected by counter methods. Compound I crystallizes in two forms, Ia and Ib. In form Ia the space group is P2₁/n with cell parameters a = 7.235(2), b = 7.717(2), c = 24.527(6) Å, β = 119.86(2)°, V = 1188(1) ų, Z = 4. In form Ib the space group is P2₁/c with cell parameters a = 14.945(5), b = 11.925(5), c = 14.878(4) Å, β = 114.51(2)°, V = 2413(3) ų, Z = 8. The molecules of I in Ia and Ib are very similar having an octahedral structure with cis oxo groups, trans thiolates (cis to both oxo groups) and N and thioether sulfur atoms trans to oxo groups. Average ditances are MoO = 1.70, MoS (thiolate) = 2.40, MoN = 2.40 and MoS (thioether) = 2.79 Å. Molecule II crystallizes in space group P2₁2₁2₁ with a = 7.188(1), b = 22.708(8), c = 7.746(2) Å, V = 1246(1) ų and Z = 4. The coordination about Mo is octahedral with cis oxo groups, trans thiolates and N atoms trans to oxo. Distances in the first coordination sphere are MoO = 1.705(2), 1.699(2), MoS = 2.420(1), 2.409(1) and MoN = 2.372(2), 2.510(2) Å. The conformational features of the complexes are discussed. Complex I displays MoO and MoS distances which are very similar to those found by EXAFS in sulfite oxidase. This similarity is discussed.     

Coordination fluxionality of copper(II) with a sterically constrained Pyrazole-containing chelating ligand. crystal and molecular structure at 298 K and 140 K of=1,6-Bis(3,5-dimethylpyrazol-1-yl)-2,5-dimethyl-2,5-diazahexane-bis(thiocyanato-N)copper(II), [C18H28CuN8S2]

The X-ray structure determinations of the compound Cu(debd)(NCS)₂ at 140 K and at 298 K showed at both temperatures a tetragonal crystal system with space group P4₁2₁2 (Z=4) and a molecular C₂ symmetry. Cell dimensions are: a= 9.577, c=24.422 Å and V=2240 ų at 140 K, and a=9.614, c=24.854 Å and V=2297 ų at 298 K. 1218 (140 K) and 1057 (298 K) reflections with I > 1.96 σ(I) were used for the solution to a final R_w value of 0.036 (140 K) and 0.032 (298 K). The copper(II) environment is roughly octahedral. The copper to nitrogen bonds vary with temperature: Cu-N(amine)=2.242 Å (140 K) and 2.191 Å (298 K), Cu-N(pyrazole)=2.099 Å (140 K) and 2.193 Å (298 K), and Cu-NCS=2.060 Å (140 K) and 2.034 Å (298 K). The ESR spectra of the Cu(II)- doped isomorphous Zn(II) and Cd(II) compounds, which have been measured at ambient temperature, at 77 K, and at 3 K, clearly reflect the temperature dependence of the structure.     

Preparation,properties, crystal and molecular structure of uranyl(VI) complexes with a new cyclic schiff base compartmental ligand

Some uranyl(VI) complexes with new acyclic and cyclic Schiff base compartmental ligands have been prepared and characterized. The ligands have been obtained by reaction of 4-chloro-2,6-diformylphenol and polyamines of the type NH₂(CH₂)₂X (CH₂)₂NH₂ (X= NH, S). The structure of the uranyl(VI) complex with the ligand 1,7,15,21-tetra- aza-4,18-dithia-11,25-dichloro 8,22-bis-metadiphenyl cyclophane-gb-7,14,21,28 has been determined by X-ray crystallography. The compound crystallizes in the orthorhombic space group Pbca with eight formula units in a cell of dimensions a = 26.654(3), b = 22.871(3), c = 8.875(5) Å. The structure was solved by standard methods and refined by full- matrix least squares to the conventional R index of 4.6% for 2678 independent observed reflexions. Five donor atoms (including sulphur) of the ligand are equatorially bonded to the uranyl group to form discrete monomeric molecules with the seven-coordinated metal in the usual distorted pentagonal bipyramidal coordination geometry. Selected bond distances are: UO (equatorial), 2.22(1) and 2.25(1) Å; UN, 2.60(1) and 2.59(1) Å; US, 3.018(4) Å.     

Formation and characterisitcs of hepatic dexamethasone-receptor complexes of different molecular weight

The dexamethasone-binding receptor protein in rat liver cytosol has a Stokes radius of 61 Å and a sedimentation coefficient of 4.0 S. In contrast, cell nuclei labelled with [³H]dexamethasone in vivo or in vitro (reconstitution experiments with [³H]dexamethasone-labelled cytosol and isolated unlabelled nuclei) contain a high-salt-extractable dexamethasone-receptor complex with a Stokes radius of 30–36 Å and a sedimentation coefficient of 3.2 S. Exposure of liver homogenate or 1000 × g homogenate supernatant to low ionic strenght during preparation of cytosol resulted in conversion of the 61 Å to a 36 Å complex very similar to the intranuclear form of dexamethasone receptor. 61 → 36 Å complex-verting activity was present in both the 100 × g ?10 000 × g sediment of liver homogenate, from which it could be extracted by hypotonic media, and in the liver cell nuclei, from which it could be extracted by hypertonic media. Mild digestion of the 61 Å dexamethasone-receptor complex with trypsin also gave rise to a complex with a Stokes radius of 36 Å. Reconstitution experiments with isolated liver cell nuclei indicated that both the 61 Å and 36 Å dexamethasone-receptor complexes were taken up by the nuclei; reextraction of the nuclei incubated with the 61 Å complex revealed that this form had been converted to the 30–36 Å complex.Further digestion of teh 61 and 36 Å [³H]dexamethasone-receptor complexes with hypotonic extract of the 1000 × g ?10 000 × g sediment of liver homogenate or with trypsin resulted in formation of a third complex with a Stokes radius of 19 Å and a sedimentation coefficient of 2.5 S. The approximate molecular weights of the 61, 36 and 19 Å dexamethasone-receptor complexes were calculated as 102 000, 46 00 and 19 000, respectively, and the frictional ratios of the molecules as 1. 84, 1. 38 amd 1.00, respectively.It is concluded that the nuclear 30–36 Å dexamethasone-receptor complex is formed from the cytosol 61 Å complex by proteolytic digestion and that this latter protein contains at least two sites with a relatively high sensitivity to protelytic cleavage.     

Synthesis,characterization, and molecular structure of the quadruply bonded ditungsten(ll) complex,W2Cl4(dppm)2

The reaction of W₂Cl₄[P(n-Bu)₃]₄ with bis(diphenylphosphino)methane (dppm) affords the highly air-sensitive material, W₂Cl₄(dppm)₂, which has been characterized by IR and visible spectroscopy, and by X-ray crystallography. The compound crystallizes in the centrosymmetric space group C2/c with the following parameters: a = 17.298(3); b = 17.011- (2); c = 18.413(2) Å; β = 98.93(2); V = 5352(2) ų; Z = 4. The molecule is positioned about a C₂ axis which allows for a net torsion angle of 17.25° down the WW vector. This does not seem to significantly effect the WW bond distance (2.269(1) Å) relative to other quadruply bonded ditungsten species.     

Crystal structure of antimony(II) monothiobenzoate,Sb(PhCOS)3

The title compound crystallizes rhombohedrally in the space group R3 with a = 20.453(11) and c = 4.197(1) Å (hexagonal setting). The structure was refined by full matrix lest squares with 585 independent reflections to R equal 0.042 (R_w = 0.040). Antimony, situated on the threefold axis, is pyramidally coordinated at 2.493(3) Å to the sulfur atoms of the three ligands. Secondary bonding occurs at 2.802(8) Å to the oxygen atoms of the asymmetrically chelating ligands.     

Architecture of the Chinese hamster metaphase chromosome

The development of procedures for the isolation of unfixed metaphase chromosomes has made feasible a direct analysis of their morphology. Wholemount stereo electron microscopy was used to examine intact and partially disrupted chromosomes produced by physical shearing and extraction with salt and urea solutions. A model of chromosome architecture was developed to accommodate evidence from studies using both light and electron microscopy. In the proposed model the chromatid (anaphase chromosome) consists of two half-chromatids; each half-chromatid contains two deoxyribonucleoprotein ribbons wound into a single fiber (termed the core), with many loops of chromatin (termed epichromatin) attached along its length. The core ribbons are each about 50 Å thick by 4000 Å wide and are composed of many parallel deoxyribonucleoprotein strands. The epichromatin loops appear to be 250 Å supercoiled fibers containing about 75 per cent of the chromosomal DNA. The epichromatin can be selectively removed from the core fibers by extraction with 2.0 M NaCl or 6.0 M urea solutions.     

X-ray structure of a mono(1-methylthyminato) complex of cisplatin,chloro-(1-methylthyminato-N3)-cis-diammineplatinum(II) monohydrate

The crystal structure of chloro-(1-methyltyminato- N3)-cis-diammineplatinum(II) monohydrate, cis- (NH₃)₂Pt(C₆H₇N₂O₂)Cl·H₂O, is reported. The compound crystallizes in space group P$\text{1}$ with a = 6.911(2) Å, b = 8.598(3) Å, c = 11.464(4) Å, α = 100.13(3)°, β = 120.03(3)°, γ = 93.16(3)°, Z = 2. The structure was refined to R = 0.048 and R_w = 0.057. The compound contains the deprotonated 1-methylthymine ligand coordinated to Pt through N3 (1.973(10) Å). This distance represents the shortest Pt-N3(pyrimidine-2.4-dione) bond reported so far. The two PtNH₃ bond lengths differ significantly: PtNH₃ (trans to Cl) is longer (2.052(10) Å) than PtNH₃ (trans to N3 of 1-MeT) (2.002(11) Å). The PtCl distance (2.326(3) Å) is normal, as is the large dihedral angle between the Pt coordination plane and the nucleobase (76.5°).     

High-yield expression,purification, characterization,and structure determination of tag-free <Emphasis Type="Italic">Candida utilis</Emphasis> uricase

We report the successful high-yield expression of Candida utilis uricase in Escherichia coli and the establishment of an efficient three-step protein purification protocol. The purity of the recombinant protein, which was confirmed to be C. utilis uricase by sodium dodecyl sulfate–polyacrylamide gel electrophoresis and matrix-assisted laser desorption/ionization time-of-flight mass spectrometer analysis, was >98% and the specific activity was 38.4 IU/mg. Crystals of C. utilis uricase were grown at 18°C using 25% polyethylene glycol 3350 as precipitant. Diffraction by the crystals extends to 1.93 Å resolution, and the crystals belong to the space group P2₁2₁2₁ with unit cell parameters a?=?69.16 Å, b?=?139.31 Å, c?=?256.33 Å, and α?=?β?=?γ?=?90°. The crystal structure of C. utilis uricase shares a high similarity with other reported structures of the homologous uricases from other species in protein database, demonstrating that the three-dimensional structure of the protein defines critically to the catalytic activities.