Promotion Effect of Streptothricin on a Glucose Oxidase Enzymatic Reaction and Its Application to a Colorimetric Assay

Determination of protamine and heparin based on their effects on a glucose oxidase enzymatic reaction

This paper describes a sensitive method for determining protamine and heparin by utilizing a glucose oxidase enzymatic reaction. Polycationic protamine significantly promoted the enzymatic reaction rate with [Fe(CN)6]3-, so that the increase could be used to determine protamine. The promotion effect was stoichiometrically decreased by the addition of polyanionic heparin through the polyion complex formation with protamine, so that the enzymatic reaction also allowed for the determination of heparin. We thus applied the proposed method to blood plasma containing heparin and found that heparin did not stoichiometrically form a polyion complex with protamine, likely due to strong interactions between heparin and some components of the plasma. The proposed method allowed for the detection of free protamine (and/or weakly binding protamine with heparin) existing in the condition that protamine did not neutralize all of the heparin in the plasma. The method also permitted for the estimation of heparin concentrations using calibration curves. Thus, the proposed method would help reduce the risks of protamine overdose in heparin neutralization and would be a helpful tool in clinical practices that use heparin and protamine.

Determination of polyanion utilizing a promoted glucose oxidase enzymatic reaction by ε-poly-L-lysine

In this paper, a sensitive determination method for polyanion using a glucose oxidase (GOx) enzymatic reaction with ferricyanide ion is described. We previously reported that the GOx enzymatic reaction was significantly promoted by a cationic polymer of ε-poly-L-lysine (εPL), and the enzymatic reaction could be utilized for the determination of εPL. Generally, polycation stoichiometrically forms polyion complex with polyanion. Thus, it is expected that the promotion effect of εPL on the enzymatic reaction is interfered by polyanion, and the enzymatic reaction is also applicable to the determination of polyanion. Predictably, the promotion effect of εPL was stoichiometrically interfered by polyanions, such as polyvinyl sulfate and polyacrylate, and the interference effect allowed for the determination of the polyanions. The detection limit of polyanion was estimated to be ~ 0.3 μeq L^-1. As a preliminary application, the proposed method was applied to the determination of anionic polymer of heparin in a human plasma.

Determination of Polyhexamethylene Biguanide Utilizing a Glucose Oxidase Enzymatic Reaction

Polyhexamethylene biguanide (PHMB) is a cationic disinfectant widely used for personal-care products and for sanitizers in swimming pools. This paper describes a promotion effect of PHMB on a glucose oxidase (GOx) enzymatic reaction with ferricyanide ion and its analytical application. The promotion effect arose from a polyion complex formation between polycationic PHMB and polyanionic GOx. The promoted GOx reaction was analyzed by Michaelis-Menten equation, and the Michalis constant and catalytic constant were estimated to be 240 μM and 31 s^-1, respectively. Utilizing the promotion effect, PHMB was successfully determined in the range of 0.05 to 0.40 ppm, and the detection limit was calculated to be 0.027 ppm. The visual detection and semi-determination of PHMB with the same concentration level were also possible. As an application, the method was applied to the determination of PHMB in a contact lens detergent and its model solution.