[pulmonary alveolar proteinosis and anti-GM-CSF antibody].
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Administration, Inhalation↗
Biomedical subjects
Kou Nakata
Publications and source records attributed to Kou Nakata.
Facile formation of water-insoluble cyclodextrin/Nafion composite films on solid surfaces.
The water-insoluble poly-beta-cyclodextrin (poly-CD)/Nafion composite film was easily prepared by casting a mixed solution of poly-CD and Nafion onto substrate plates. FT-IR measurements showed that the 50/50 wt% poly-CD/Nafion composite film remained stable on the glass and quartz substrates after immersion in water for more than 3 h, while a pure poly-CD film was almost completely dissolved by immersion within 1 h. The film stability was also evaluated from the amount of p-nitrophenol (p-NP) inclusion in the film, which was determined from the decrease in UV-vis absorbance of the p-NP solution into which the film was immersed. The composition dependence of the inclusion amount showed that the film was stable up to 50 wt% CD, but became less stable with further increase in the CD concentration in the film. From the isotherms for the inclusion of p-NP and 1-naphthoate (1-Naph) into the film, the inclusion (stability) constants were determined to be 3.7x10(3) M(-1) and 1.9x10(2) M(-1), respectively. These results show that the selective inclusion of CD is retained after preparation of the composite film.
Journal Article↗
Nucleophilic reaction by carbonic anhydrase model zinc compound: characterization of intermediates for CO2 hydration and phosphoester hydrolysis.
The partially hydrophilic and hydrophobic tripodal ligands, tris(hydroxy-2-benzimidazolylmethyl)amine L1h and tris(2-benzimidazolyl)amine L1 were used for the preparation of biomimetic complex of carbonic anhydrase. The CO(2) hydration using [L1hZn(OH)]ClO(4).1.5H(2)O provided the zinc-bound and free HCO(3)(-)s, which were formed by nucleophilic attack of Zn-OH toward CO(2) in dimethyl sulfoxide (DMSO). The phenolic OH in L1h can recognize water molecules through hydrogen bonds to facilitate the collection of the water molecules around a biomimetic zinc compound; the molecular structure of [L1hZn(OH)](+) was revealed. The packing diagram has demonstrated the all the water molecules are hydrogen bonded to each phenolic OH. The nucleophilic attack of zinc-bound OH(-) to substrate is used to catalyze the CO(2) hydration and phosphoester hydrolysis. The carbonic anhydrase model compound [L1Zn(OH(2))](2+) was applied for the hydrolysis of phosphoesters, parathion and bis(p-nitrophenyl)phosphate (BNPP(-)). The low reactivity of [L1Zn(OH)](+) for parathion hydrolysis is attributed to the stability of the intermediate [L1Zn(OP(S)(OEt)(2))](+). Since the structures of the intermediates [L1Zn(OH(2))](BNPP)(2) (1) and [L1Zn(OP(S)(OEt)(2))]ClO(4) (2) formed on the way of hydrolysis are too stable to realize the catalytic cycle and are not active for hydrolysis, carbonic anhydrase model compound [L1Zn(OH(2))](2+) was not suitable for phosphoester hydrolysis; the zinc model compound surrounded by three benzimidazolyl groups is used to have the steric hindrance for bulky substrate, such as parathion and BNPP(-).
Binding Sites↗
Hydrolysis of natural and artificial phosphoesters using zinc model compound with a histidine-containing pseudopeptide.
Zinc(II) complex with histidine-containing pseudopeptide derived from N,N'-bis(benzylhistidyl) diethylenetriamine L was examined as catalyst for the hydrolysis of bis(p-nitrophenyl) phosphate (BNPP), p-nitrophenyl phosphate (NPP), adenylyl-(3'-5')adenosine (ApA), thymidylyl-(3'-5') thymidine (TpT) and PBR 322 supercoiled DNA. The stepwise protonation constants of the ligand, stability constants for its zinc(II) complex LZn have been determined potentiometrically in aqueous solution. LZn efficiently hydrolyzed BNPP and NPP and their pseudo-first-order rate constants k(obs) are 1.1 x 10(-5) s(-1) and 2.1 x 10(-5) s(-1), respectively. Bell-shaped pH-k(obs) profile was seen in BNPP hydrolysis around pH 7. Kinetic parameters were obtained from temperature dependence of hydrolysis rate constants where entropy of activation showed considerably high negative value. ApA and TpT as RNA-type and DNA-type dinucleotides were slowly hydrolyzed by LZn. On the basis of the kinetic evidence of bell-shaped pH-k(obs) profile and species distribution curve, we propose a mechanism for LZn-promoted hydrolysis of BNPP as well as ApA where cooperative achieve of zinc-hydroxo and zinc-aqua complex species may be responsible for enzymatic activity. The agarose gel electrophoresis and AFM demonstrated that LZn performed good activity on the selective cleavage of pBR322 supercoiled DNA at pH 7.0 providing evidence for its probable applicability.
Histidine↗
Kinetic study of catalytic CO(2) hydration by water-soluble model compound of carbonic anhydrase and anion inhibition effect on CO(2) hydration.
A kinetic study of CO(2) hydration was carried out using the water-soluble zinc model complex with water-soluble nitrilotris(2-benzimidazolylmethyl-6-sulfonate) L1S, [L1SZn(OH(2))](-), mimicking the active site of carbonic anhydrase, in the presence and absence of anion inhibitors NCS(-) and Cl(-). The obtained rate constants k(cat) for CO(2) hydration were 5.9x10(2), 1. 7x10(3), and 3.1x10(3) M(-1) s(-1) at 5, 10, and 15 degrees C, respectively: the k(cat)=ca. 10(4) M(-1) s(-1) extrapolated towards 25 degrees C has been the largest among the reported k(cat) using zinc model complexes for carbonic anhydrase. It was also revealed that NCS(-), Cl(-) and acetazolamide play a role of inhibitors by the decrease of k(cat): 7x10(2) and 2x10(3) M(-1) s(-1) for NCS(-) and Cl(-) at 15 degrees C, respectively. The sequence of their magnitudes in k(cat) is Cl(-) approximately acetazolamide>NCS(-), where the sequence Cl(-)>NCS(-) is confirmed for native carbonic anhydrase. The difference of k(cat) or k(obs) between NCS(-) and Cl(-) resulted from that between the stability constants K(st)=2x10(3) for [L1SZn(NCS)](2-) and 1x10(2) M(-1) for [L1SZnCl](2-) in D(2)O: for water-insoluble tris(2-benzimidazolylmethyl)amine L1, K(st)=1.8x10(4) for [L1Zn(NCS)](2-) and 1.5x10(3) M(-1) for [L1ZnCl](2-)in CD(3)CN/D(2)O (50% v/v). The crystal structure of anion-binding zinc model complexes [L1Zn(OH(2))](0.5)[L1ZnCl](0.5) (ClO(4))(1.5) 1(0.5)2(0.5)(ClO(4))(1.5) was revealed by X-ray crystallography. The geometry around Zn(2+) in 1 and 2 was tetrahedrally coordinated by three benzimidazolyl nitrogen atoms and one oxygen atom of H(2)O, or Cl(-).
Anions↗
Sutureless contact lens ring system during vitrectomy.
PURPOSE: To report a new sutureless ring system to fix corneal contact lens in place during vitrectomy. DESIGN: New surgical instrument. METHODS: The sutureless ring system consists of a stainless steel ring that has two upright tabs 180 degrees apart with a hook on the top and two elastic silicone bands 8 mm in diameter to fix the ring to the eyelid speculum. RESULTS: The contact lens fixed in place with the sutureless ring was stable and allowed intraoperative visualization of the fundus. CONCLUSION: This suture-free contact lens system facilitates visualization of the fundus during vitrectomy allowing shorter surgical time. It also enables us to avoid additional trauma associated with the lens ring fixation procedure.
Contact Lenses↗