Publications by authors named "Junzo Hirose"

The ESR spectra of dicupric human serum-transferrin (serum-Tf) were measured from -20 to 37°C in the liquid state (56% glycerol at pH 7.6). Two coordination geometries (types B-1 and B-2) with different ESR parameters were present at the N-site.

View Article and Find Full Text PDF

The metal dissociation constants of bovine carbonic anhydrase II, bovine carboxypeptidase A, rat aminopeptidase B, and rat dipeptidyl peptidase III were measured using metal buffer solutions. The zinc dissociation constants of bovine carbonic anhydrase II, bovine carboxypeptidase A, rat aminopeptidase B, and rat dipeptidyl peptidase III were 5.8×10(-14), 3.

View Article and Find Full Text PDF

Antioxidant activities of 3-oxygenated and 3,4-dioxygenated carbazole alkaloids and their related carbazoles were comprehensively evaluated. In all assay systems, the 3,8-dihydroxycarbazoles carbazomadurin A (2) and B (3), and their synthetic precursors 2a and 3a exhibited higher antioxidant activities than the 3-monohydroxycarbazoles carazostatin (1), and the synthetic precursors 4a and 4b of carquinostatin A (4). In particular, 2a and 3a exhibited strong scavenging activities due to the reducing ability of formyl group at the C-5 position of carbazoles.

View Article and Find Full Text PDF

  The text mining and full-text searching function were used to analyze the digitalized daily reports of the practical training in pharmacology submitted to the web system in Fukuyama University. Collocations connected to the word "inspection" were searched in the daily reports using the text mining and the full-text search functions of the system. Many collocation groups connected to "inspection" were found in the daily reports and the greatest number of collocations was associated with "preparation of drugs".

View Article and Find Full Text PDF
Article Synopsis
  • Dipeptidyl peptidase III (DPP III) contains a unique helix in its metal-binding region, which is crucial for enzyme activity.
  • Cu(II)-rat DPP III demonstrates reduced activity compared to its wild-type form, while a modified version with a deletion (del-DPP III) drastically loses its enzyme function.
  • The deletion of Leu453 disrupts the enzyme's flexibility around copper ions, affecting the formation of the enzyme-metal-substrate complex and altering the accessibility of a key residue (Glu451) to water.
View Article and Find Full Text PDF
Article Synopsis
  • Most naturally occurring metalloproteases are monozinc enzymes, which can have zinc replaced by other divalent cations like Co(II) or Mn(II) without losing catalytic activity.
  • While most enzymes maintain activity with Co(II) or Mn(II), many Cu(II)-substituted enzymes, such as thermolysin and carboxypeptidase A, lose activity, though some, like astacin, retain partial to full activity.
  • Structural studies suggest that the activity of Cu(II)-substituted enzymes depends on the flexibility of the catalytic domain, even though their metal coordination geometries resemble those of the original zinc enzymes.
View Article and Find Full Text PDF

Dipeptidyl peptidase (DPP) III is a zinc-dependent exopeptidase that has a unique motif, "HELLGH," as the zinc-binding site. In the present study, a three-dimensional (3D) model of rat DPP III was generated with the X-ray crystal structure of human DPP III (PDB: 3FVY [Dobrovetsky E. et al.

View Article and Find Full Text PDF

The antioxidant properties of different low molecular weight (LMW) chitosans (CS1; 22 kDa, CS2; 38 kDa, CS3; 52 kDa, CS4; 81 kDa) were examined for possible use in extended-release tablets. The criteria used were the ability of the chitosans to reduce Cu, and hydroxyl and superoxide radicals and N-centered radicals derived from 1,1'-diphenyl-2-picrylhydrazyl, via the use of ESR spectrometry. CS2 showed the highest scavenging activity.

View Article and Find Full Text PDF

Timolol, a beta-blocker, has been shown to be an effective ocular hypotensive agent when used alone or with carbonic anhydrase inhibitor on ocular hypertensive or open angle glaucoma patients. The effect of timolol hemihydrate on the CO(2) hydration activities of human carbonic anhydrase (HCA) I and II and their reaction mechanisms were investigated. Timolol activates the enzyme activities of HCA I and HCA II.

View Article and Find Full Text PDF

Latanoprost, a prostaglandin F2 alpha analogue, has been shown to be an effective ocular hypotensive agent when used alone on ocular hypertensive or open angle glaucoma patients. Carbonic anhydrase (CA) inhibitors are also used to reduce ocular hypertension by decreasing aqueous humor secretion, and are given in combination with prostaglandin F2 alpha analogue. It has been shown that prostaglandin F2 alpha, Minprostin F2 alpha, has been shown to increase the carbonic anhydrase (CA) activity and blood pressure.

View Article and Find Full Text PDF
Article Synopsis
  • A recombinant rat aminopeptidase-B (Ap-B) was produced in E. coli as a GST fusion protein and purified through specific chromatography methods.
  • Metal-substituted variants of Ap-B (Co(II)- and Cu(II)-Ap-B) were created, with Co(II)-Ap-B showing activity similar to the original enzyme, while Cu(II)-Ap-B demonstrated significantly lower activity.
  • The study measured dissociation constants for zinc and cobalt in the enzymes and reported EPR parameters for Cu(II)-Ap-B, highlighting its distorted tetrahedral coordination geometry similar to other copper-enzyme complexes.
View Article and Find Full Text PDF

The zinc-binding motif (HELLGH) of dipeptidyl peptidase III (DPP III) is different from the common zinc-binding motif (HExxH) of metallopeptidases. To clarify the importance of the zinc-binding motif part of DPP III for enzymatic activity, we measured the recovery of the enzyme activity of apo-Leu(453)-deleted dipeptidyl peptidase III (apo-Leu(453)-del-DPP III), which has a motif (HELGH) like that of the common peptidase (HExxH), in the presence of various metal ions. The enzyme activity of apo-Leu(453)-deleted DPP III could not be recovered by the addition of cupric ions, while apo-DPP III could be easily reactivated by the addition of cupric ions.

View Article and Find Full Text PDF