Development of agmatine sensor using the combination of putrescine oxidase and agmatinase for squid freshness

• Published in: Biosensors & bioelectronics Vol. 20; no. 4; pp. 833 - 840
• Main Authors: Inaba, Yohei, Tokishita, Shinichi, Hamada-Sato, Naoko, Kobayashi, Takeshi, Imada, Chiaki, Yamagata, Hideo, Watanabe, Etsuo
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 01.11.2004; Elsevier Science
• Subjects: Agmatinase; Agmatine; Agmatine - analysis; Animals; Biological and medical sciences; Biosensing Techniques - instrumentation; Biosensing Techniques - methods; Biosensors; Biotechnology; Decapodiformes - chemistry; Electrochemistry - instrumentation; Electrochemistry - methods; Flow injection analysis; Flow Injection Analysis - instrumentation; Flow Injection Analysis - methods; Food Analysis - instrumentation; Food Analysis - methods; Fundamental and applied biological sciences. Psychology; Methods. Procedures. Technologies; Microchemistry - instrumentation; Microchemistry - methods; Oxidoreductases Acting on CH-NH Group Donors - chemistry; Putrescine oxidase; Squid freshness indicator; Systems Integration; Ureohydrolases - chemistry; Various methods and equipments; Squid freshness indicator; Putrescine oxidase; Flow injection analysis; Agmatinase; Agmatine; Enzyme; Cephalopoda; Detector; Squid; Biosensor; Hydrolases; Freshness; Oxidoreductases; Invertebrata; Mollusca; Flow injection
• ISSN: 0956-5663; 1873-4235
• DOI: 10.1016/j.bios.2004.03.022

Agmatine (Agm) is an indicator of squid freshness. The Agm sensor was developed using flow injection analysis (FIA) that consisted of the putrescine oxidase (PuOx) reactor, the agmatinase (AUH)–PuOx reactor and two oxygen electrodes. In the proposed sensor, the first step is that coexisting cadaverine (Cad) and putrescine (Put) are removed by passing through the PuOx reactor and the initial decomposition is determined by the amount of oxygen consumed, simultaneously. The second step is that the amount of Agm is determined by the amount of oxygen consumed in the AUH–PuOx reactor. The optimum conditions for the use of the Agm sensor were as follows: 50 mM HEPES containing MnSO 4 at a final concentration of 5 mM, pH 8.0, flow rate of 0.6 mL min −1 and injection volume of 50 μL. A single assay could be completed in approximately 3 min. A linear relationship was obtained between the output and the Agm concentration in the range of 0.01–1 mM Agm with a correlation coefficient of 0.999. The detection limit was 0.005 mM. The relative standard deviations (RSDs) were 3.14 and 1.19% ( n=20) for 0.1 and 0.3 mM Agm, respectively. The extracts of squid were injected into the proposed sensor and the results were compared with those obtained using the conventional high-performance liquid chromatography (HPLC) method. A correlation was observed between the results obtained by the proposed sensor and those obtained by the conventional method. The determination of squid freshness is one of the good uses of the proposed Agm sensor.