Analytical Sciences

Fluorescent Derivatization of Aromatic Carboxylic Acids with Horseradish Peroxidase in the Presence of Excess Hydrogen Peroxide

Junichi ODO, Masahiko INOGUCHI, Hiroyuki AOKI, Yuto SOGAWA, and Masahiro NISHIMURA

Department of Biological Chemistry, Faculty of Science, Okayama University of Science, 1-1 Ridai-cho, Kita, Okayama 700-0005, Japan

The fluorescent derivatization of aromatic carboxylic acids by the catalytic activity of horseradish peroxidase (HRP) in the presence of excess H₂O₂ was investigated. Four monocarboxylic acids, nine dicarboxylic acids, and two tricarboxylic acids, all of which are non- or weakly fluorescent, were effectively converted into fluorescent compounds using this new method. This technique was further developed for the fluorometric determination of trace amounts of terephthalic acid (3c) and lutidinic acid (2b), and linear calibration curves for concentrations between 2.5 and 20.0 nmol of terephthalic acid (3c) and 1.0 and 10.0 nmol of lutidinic acid (2b) were demonstrated. Compound III, an intermediate of HRP, played an essential role in this process. Additionally, lactoperoxidase and manganese peroxidase, peroxidases similar to HRP, showed successful fluorescent derivatization of nicotinic acid (1b), lutidinic acid (2b), and hemimellitic acid (4a) in the presence of excess H₂O₂.

J-STAGE: View this article in J-STAGE