• Molecules and Cells
• /
• v.43 no.9
• /
• pp.831-840
• /
• 2020

The β-class of carbonic anhydrases (β-CAs) are zinc metalloenzymes widely distributed in the fungal kingdom that play essential roles in growth, survival, differentiation, and virulence by catalyzing the reversible interconversion of carbon dioxide (CO₂) and bicarbonate (HCO₃^-). Herein, we report the biochemical and crystallographic characterization of the β-CA CafA from the fungal pathogen Aspergillus fumigatus, the main causative agent of invasive aspergillosis. CafA exhibited apparent in vitro CO₂ hydration activity in neutral to weak alkaline conditions, but little activity at acidic pH. The high-resolution crystal structure of CafA revealed a tetramer comprising a dimer of dimers, in which the catalytic zinc ion is tetrahedrally coordinated by three conserved residues (C119, H175, C178) and an acetate anion presumably acquired from the crystallization solution, indicating a freely accessible "open" conformation. Furthermore, knowledge of the structure of CafA in complex with the potent inhibitor acetazolamide, together with its functional intolerance of nitrate (NO₃^-) ions, could be exploited to develop new antifungal agents for the treatment of invasive aspergillosis.

• Bulletin of the Korean Chemical Society
• /
• v.11 no.1
• /
• pp.15-19
• /
• 1990

The crystal structure of $(C_{12}H_{24}O_6{\cdot}K)_2K[Co(OH)_6Mo_6O_{18}]{\cdot}12H_2O$ has been determined by X-ray diffraction. Crystal data as follows ; monoclinic, space group $C_2/m,\;a\;=\;22.512(4)\;{\AA},\;b\;=\;18.304(4)\;{\AA},\;c\;=\;7.641(1)\;{\AA},\;{\beta}\;=\;90.52(2)\;{\AA}$, and Z = 2. A final conventional R value of 0.044 was obtained by least-squares refinement of 4173 independent observed $[{\mid}Fo{\mid}{\geq}3{\sigma}({\mid}Fo{\mid})]$ reflections. The $[Co(OH)_6Mo_6O_}{18}]^{-3}$ polyanion shows the well-known Anderson-structure and has approximate 3m symmetry. A $[Co(OH)_6Mo_6O_{18}]^{-3}$ polyanion is located between two crown ether complexed cations forming a sandwich structure. One potassium ion interacts with the crown ether via electrostatic interactions. The other potassium ion only interacts with the water molecules and terminal oxygen atoms of the polyanion.

• Bulletin of the Korean Chemical Society
• /
• v.14 no.6
• /
• pp.722-726
• /
• 1993

Organotin(IV) complexes of ylidenemalonates $(R_xSn)_{x-1}(O_2C)_2C=C(SR')_2\;(R=n-C_4H_9,\;C_6H_5,\;cyclo-C_6H_{11},\;CH_3OOCCH_2CH_2;\;x=2,3;\;R'=CH_3,\;R_2'=-CHCH-,\;-CH_2CH_{2^-})$ have been synthesized and characterized by means of various spectroscopic methods. The X-ray crystal structure of $(Ph_3Sn)_2(O_2C)_2C=C(SCH_3)_2$ has been determined (Pi; a= 9.704(2) ${\AA}$, b= 14.412(1) ${\AA}$, c= 14.760(3) ${\AA}$, ${alpha}$=74.26(1)$^{\circ}$, ${beta}$=99.38(l)$^{\circ}$, ${\gamma}$=79.09(1)$^{\circ}$, $V= 1950.7(7){\AA}^3$) and refined to R= 0.045. The crystal structure discloses a discrete molecule with bidentate-like carboxylate ligand. For diorganotin analogues, the structures are discussed in terms of IR, $^1H-NMR,\;^{13}C-NMR$, and FAB mass spectrometry. The mass spectrum indicates that the diorganotin complexes of ylidenemalonates are dimeric.

• Bulletin of the Korean Chemical Society
• /
• v.12 no.4
• /
• pp.371-373
• /
• 1991

The crystal structure of eprazinone dihydrochloride, $C_{24}H_{32}N_2O_2$${\cdot}$2HCl, has been determined from 2102 independent reflections collected on an automated Nonious CAD-4 diffractometer using graphite-monochromated $Mo-K\alpha$ radiation. The crystals are monoclinic, space group P$2_1$/n, with unit cell dimensions a=11.381(2), b=28.318(2), c=7.840(1) $\AA$, $\beta=92.45(2)^{\circ}$, ${\mu}=2.37$ c$m^{-1}$, F(000)=968, and Z=4. Final R value is 0.071 for independent 2102 observed reflections. The molecule assumes an extended conformation. The piperazine ring has a normal chair conformation and the four carbon atom are planar with a maximum displacement of 0.004 $\AA$ for C(18) atom. The two chloride ions are hydrogen bonded to the two piperazine nitrogen atoms [N(14)${\cdot}{\cdot}{\cdot}$Cl(1); 2.986(6) $\AA$ N(17)…Cl(2); 3.084(8) $\AA$].

• Bulletin of the Korean Chemical Society
• /
• v.11 no.5
• /
• pp.427-430
• /
• 1990

Cholesteryl aniline ($C_{33}H_{51}N$) is monoclinic, space group $P2_1$, with a = 9.020(3), b = 6.000(1), c = 27.130(9)${\AA},\;{\beta} = 98.22(2)^{\circ}$, Z = 2, Dc = 1.06 g/cm$^3$ and Dm = 1.04 g/cm$^3$. A diffraction data set was collected with Mo-$K_{\alpha}$ radiation (${\lambda} = 0.7107 {\AA}$) on a diffractometer with a graphite monochromator to a maximum 2${\theta}$ value of 50$^{\circ}$, by the ${\omega}-2{\theta}$ scan technique. The coordinates of the non-hydrogen atoms and their anisotropic temperature factors were refined by full-matrix least-squares methods to final R of 0.058. In cholesteryl group, bond distances were normal except in tail part, where high thermal vibration resulted in apparent shortening of the C-C distances. The crystal structure consists of bilayers of thickness $d_{001} = 27.13 {\AA}$, in each of which there is the tail to tail arrangement of molecules aligned in the unit cell with their long axes approximately parallel to the [104] axis. The two halves of the double layer are related to each other by the screw axis.

• Bulletin of the Korean Chemical Society
• /
• v.15 no.6
• /
• pp.432-436
• /
• 1994

Monomeric rhodium and iridium-diaryltetrazene complexes $Cp^*$M(RNN=NNR)($Cp^*$=1,2,3,4,5-pentamethylcyclope ntadienyl; M=Rh, Ir; R=Ph, 4-tolyl) have been synthesized from [$Cp^*MCl_2]_2$(M=Rh, Ir) and 2 equiv. of $[Li(THF)_x]_2(RN_4$R) in benzene. We have determined the crystal structure of (${\eta}^5$-pentamethylcyclopentadienyl)diphenyltetrazene iridium by using graphite-monochromated Mo-$K_a$ radiation. The compound was crystallized in the monoclinic space group $P2_{1/c}$ with a=13.781(3), b=9.035(l), c=17.699(3) ${\AA}$, and ${\beta}=111.93(l)^{\circ}$. An X-ray crystal structure of complex 1 showed a short N(2)-N(3) distance ($1.265 {\AA}$) consistent with the valence tautomer A with Ir(III) rather than Ir(I). All complexes are highly colored and decompose on irradiation at 254 nm. Electrochemical studies show that complex 1 displays a quasi-reversible reduction.

• Bulletin of the Korean Chemical Society
• /
• v.13 no.5
• /
• pp.542-546
• /
• 1992

New silicon-monosubstituted (${\eta}^4$-2,3,4,5-tetraphenyl-1-silacyclopentadiene)transi tion metal complexes are described. The new (silole-transition metal complex)Fe$(CO)_3$ was obtained from the reaction of silole-tansition metal complex and Fe$(CO)_5$. We have determined the crystal structure of (${\eta}^4$-exo-cyclopentadienyldicarbonyliron-endo-1-meth yl-2,3,4,5-tetraphenyl-1-silacyclopentadienyl)tric arbonyliron by using graphitemonochromated Mo-$K_{\alpha}radiation. The compound was crystallized in the monoclinic space group $P2_1$/c with a = 8.925(1), b = 18.689(3), c = 19.930(3) ${\AA}$, and ${\beta}$ = 102.02$(1)^{\circ}$. The iron moiety CpFe$(CO)_2$ on silicon is in an axal position. The (silole-transition metal complex) Fe$(CO)_3$ was also prepared through the reaction of (${\eta}^4$-1-chloro-2,3,4,5-tetraphenylsilacyclopentadiene) Fe$(CO)_3$ and metal complex nucleophile. The structure configuration was studied by conventional spectroscopy.

• Bulletin of the Korean Chemical Society
• /
• v.10 no.2
• /
• pp.177-184
• /
• 1989

The structure of cholesteryl isobutyrate, $(CH_3)_2CHCOOC_{27}H_{45}$, was determined by single crystal X-ray diffraction methods. Cholesteryl isobutyrate crystallized monoclinic space group $P2_1$, with a = 15.115 (8)${\AA}$, b = 9.636 (5)${\AA}$, c = 20.224 (9)${\AA}$, ${\beta}$ = 93.15 (5)$^{\circ}$, z = 4, $D_c = 1.03 g/cm^3 $and Dm= 1.04 g/$cm^3$. The intensity data were measured for the 3417 reflections, within $sin{\theta}/{\lambda} = 0.59{\AA}^{-1}$, using an automatic four-circle diffractometer and graphite monochromated Mo-$K_{\alpha}$ radiation. The structure was solved by fragment search Patterson methods and direct methods and refined by full-matrix least-squares methods. The final R factor was 0.129 for 2984 observed reflections. The two symmetry-independent molecules (A) and (B) are almost fully extended. The molecules are in antiparallel array forming monolayers with thickness $d_{100}$ = 15.2${\AA}$, and molecular long axes are nearly parallel to the [$\bar{1}$01] directions. The two distinct molecules form separate stacks with almost the same orientations, but with differing degrees of steroid overlap. Thers is a close packing of cholesteryl groups within the monolayers. The packing type is similar to those of cholesteryl hexanoate and cholesteryl oleate.

• Analytical Science and Technology
• /
• v.20 no.4
• /
• pp.355-360
• /
• 2007

The title complex, $(C_3H_{12}N_2)[\{Cd(H_2O)(C_6H_5O_7)\}_2]{\cdot}6H_2O$, I, has been prepared and its structure characterized by FT-IR, EDS, elemental analysis, ICP-AES, and X-ray single crystallography. It is triclinic system, $P{\bar{1}}$ space group with a = 10.236(2), b = 11.318(2), c = $13.198(2){\AA}$, ${\alpha}=77.95(1)^{\circ}$, ${\beta}=68.10(1)^{\circ}$, ${\gamma}=78.12(1)^{\circ}$, V = $1373.5(3){\AA}^3$, Z = 2. Complex I has constituted by protonated 1,3-diaminopropane cations, citrate coordinated cadmium(II) anions, and free water molecules. The central cadmium atoms have a capped trigonal prism geometry by seven coordination with six oxygen atoms of three different citrate ligands and one water molecule. Citrate ligands are bridged to three different cadmium atoms. Each cadmium atom is linked by carboxylate and hydroxyl groups of citrate ligand to construct an one-dimensional ladder-type assembly structure. The polymeric crystal structure is stabilized by three-dimensional networks of the intermolecular O-H${\cdots}$O and N-H${\cdots}$O hydrogen-bonding interaction.

• Journal of the Korean Chemical Society
• /
• v.20 no.1
• /
• pp.19-34
• /
• 1976

The crystal structure of sodium sulfisoxazole hexahydrate, $C_{11}H_{12}N_3O_3SNa{\cdot}6H_2O$,has been determined by X-ray diffraction method. The compound crystallizes in the monoclinic space group $$P2_1}c$$ with a = 15.68(3), b = 7.70(2), c = 17.94(4)${\AA}$, ${\beta}$ = $118(2)^{\circ}$ and Z = 4. A total of 1717 observed reflections were collected by the Weissenberg method with $CuK{\alpha}$ radiation. Structure was solved by heavy atom method and refined by block-diagonal least-squares methods to the R value of 0.14. The conformational angle formed by the S-C(l) bond with that of N(2)-C(7), when the projection in taken along the S-N(2), is $73^{\circ}.$ The benzene ring is planar and makes an angle of $60^{\circ}$ with the plane of the isoxazole ring, which is also planar. The sodium atom has a distorted octahedral coordination of N(l) and five oxygen atoms from hydrate molecules. Sodium sulfisoxazole hexahydrate shows fourteen different hydrogen bondings in the crystal. These are six $O-H{\cdots}O-H bonds, three $O-H{\cdots}O$ bonds, two $O-N{\cdots}N,$ one $N-H{\cdots}O,O-H{\cdots}N,N-H{\cdots}O-H$ bond, with the distances in the range of 2.71 to $3.04{\AA}.$.