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

Determination of Polyhexamethylene Biguanide Utilizing a Glucose Oxidase Enzymatic Reaction

“…The promotion effect by multivalent cations is strongly influenced by the pH and the ionic strength of the assay solution, because the effect arises from the ion-complex formation between the multivalent cation and negatively charged GOx. 18,19,23 The influences of pH and ionic strength on the PHMB's promotion effect were investigated. Figure 3 shows plots of the enzymatic reaction rate, vE, in the absence (open symbols) and presence (filled symbols) of 10 ppm PHMB as a function of pH.…”

“…As reported previously, the GOx reaction accompanied by a color change due to the reduction of [Fe(CN)6] 3-, and the color change can be distinguished by addition of Fe(III) ion through the formation of Prussian blue. 19,22 Figure 8B shows assay solutions immediately after the addition of FeCl3 to the reaction solution where the enzymatic reaction proceeded for 30 min (that is, the assay solution used in Fig. 7).…”

“…7,17 However, in our previous studies, we found that the GOx reaction with [Fe(CN)6] 3is significantly promoted by ε-poly-L-lysine (εPL) and streptothricin. 18,19 These compounds have a number of amino groups in lysine residues, and exist as polyvalent or multivalent cation under acidic and neutral conditions. 20,21 Thus, these cationic species can be easily detected using the GOx enzymatic reaction.…”

“…20,21 Thus, these cationic species can be easily detected using the GOx enzymatic reaction. 19,22 From investigations of the influences of pH, ionic strength and ionic charge of oxidants on the promotion effect, 18,19,23 it has been deduced that these polycationic species associate with the polyanionic GOx, and reduces an electrostatic repulsion between negatively charged GOx and [Fe(CN)6] 3-, resulting in promoting the GOx enzymatic reaction. Thus, it is expected that polycationic PHMB also promotes the GOx enzymatic reaction, and that PHMB can be detected by the reaction.…”