Tsuyoshi Izumi

Complexation of papain with strong polyanions and enzymatic activities of the resulting complexes

Abstract The complexation of papain (EC.3.4.22.2) with potassium polyvinyl alcohol) sulfate (KPVS) and sodium poly(styrene sulfonate) (NaPSS) was studied at different pH levels by means of colloid titration. The enzymatic activities of the resulting complexes were also studied as a function of pH and temperature, using Nα-benzoyl-DL-arginine-p-nitroanilide as the substrate. The moles (M s)of the sulfate or sulfonate groups in the polyelectrolytes that took part in the complexation with 1 g papain varied depending on pH due to a pH-induced change in the protonation of the protein basic groups: 11 amino (including one N-terminal), 2 imidazolyl, and 12 guanidyl groups. However, the curves of M s vs pH were independent of neither the species of the polyelectrolytes nor the molecular weight of NaPSS. On the other hand, the pH-activity curve of papain was shifted toward the alkaline pH range upon complexation, which occurred only in a region of pH < 5.5, without an accordant shift of the optimum pH (near 6.5 fo...

Spectroscopic Studies on the Complexation of Papain with Potassium Poly(Vinyl Alcohol Sulfate)

Abstract The complexation of papains (EC.3.4.22.2) with potassium polyvinyl alcohol sulfate) (KPVS) in aqueous solutions as a function of pH was studied using fluorescence spectroscopy. A maximum emission at 333 nm was observed in aqueous diluted papain solutions (concentration < 10−6 mol/dm3) not containing KPVS. As the concentration of papain increased, the positions of the maximum emission were blue shifted; that is, the difference in wavelength from 333 nm increased with an increase in the protein concentration. A similar shift was observed when KPVS was added to papain solutions at a constant concentration (10−6 mol/ dm3) with pH values which had been adjusted to 2 and 7. However, such a shift was not observed at pH 10. In addition, the effect of KPVS on the maximum emission shift was larger at pH 7 than at pH 2. These results are discussed in connection with the protein/protein interaction within an intrapolymer papain/KPVS complex.

Pharmaceutical production of tableting granules in an ultra-small-scale high-shear granulator as a pre-formulation study.

Objective: In some of drug developments, the amount of bulk drug powder to use in early stages is limited and it is not easy to supply a sufficient drug amount for conventional preparation methods. Therefore, an ultra-small-scale high-shear granulator (less than 5 g) (USG) was developed and applied to small-scale granulation as a pre-formulation. Method: The sample powder consisted of 66.5% lactose, 28.5% microcrystalline cellulose and 5.0% hydroxypropylcellulose. The granules were obtained to agitate 5 g of the sample powder with 1.0 mL of water at 300 rpm for 5 min after pre-powder mixing for 3 min by the USG and the manual hand (HM) methods. Results: The granules were evaluated by the 10% and 90% accumulated particle size and the recoveries of the granules and the powder solid. Median particle size for the USG and the HM methods was 159.2 ± 2.3 and 270.9 ± 14.9 µm, respectively. The USG method had a narrower particle size distribution than those by the HM method. The recovery of the granules by USG was significantly larger than that by the HM method. Conclusion: Characteristics of all of the granules indicated that the USG method could produce higher quality granules within a shorter time than the HM methods.

Interactions of water-soluble polymers with small molecules I: Poly(2-diethylaminoethyl methacrylate)-orange II and ethyl orange systems

The interactions between poly(2-diethylaminoethyl methacrylate) (PDEAEMA) and orange II (OII) or ethyl orange (EO) have been examined in detail by measuring the transmittance and the specific conductance of the solutions. The mechanisms of flocculation and deflocculation have been investigated by changing the intrinsic viscosity, the degree of neutralization and alkyl groups of PDEAEMA or by adding NaCl, urea or alcohols. The complexation of PDEAEMA with dyes is completed at the same mole ratio but is not dependent on the molecular weight of PDEAEMA. OII molecules bind with PDEAEMA by electrostatic interactions, followed by flocculation through hydrogen bondings between hydroxyl groups on OII molecules bound. EO molecules first interact with PDEAEMA electrostatically in the same ways as OII, but flocculation occurs by hydrophobic interactions between ethyl groups on EO molecules bound. By further addition of dyes to the complex, OII or EO molecules already bound can interact with free OII or EO molecules newly added through hydrogen/hydrophobic interaction between OII or EO molecules. Deflocculation occurs by the electrostatic repulsion between anions of dyes bound, such as (PDEAEMA-OII)-hydrogen bonding-(OII-anions) or (PDEAEMA-EO)-hydrophobic bonding-(EO-anions) newly formed.