title: Development of agmatine sensor using the combination of putrescine oxidase and agmatinase for squid freshness.
abstract: 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 MnSO4 at a final concentration of 5 mM, pH 8.0, flow rate of 0.6 mL min(-1) and injection volume of 50 microL. 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.
authors.affiliation: Department of Food Science and Technology, Tokyo University of Fisheries, 5-7 Kounan 4, Minato-ku, Tokyo 108-8477, Japan.
authors.forename: Yohei
authors.initials: Y
authors.lastname: Inaba
authors.forename: Shinichi
authors.initials: S
authors.lastname: Tokishita
authors.forename: Naoko
authors.initials: N
authors.lastname: Hamada-Sato
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Chiaki
authors.initials: C
authors.lastname: Imada
authors.forename: Hideo
authors.initials: H
authors.lastname: Yamagata
authors.forename: Etsuo
authors.initials: E
authors.lastname: Watanabe
mesh_terms: D000376:Agmatine / Q000032:analysis*; D000818:Animals; D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods; D049832:Decapodiformes / Q000737:chemistry*; D004563:Electrochemistry / Q000295:instrumentation* / Q000379:methods; D017022:Flow Injection Analysis / Q000295:instrumentation / Q000379:methods; D005504:Food Analysis / Q000295:instrumentation* / Q000379:methods; D008832:Microchemistry / Q000295:instrumentation / Q000379:methods; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000737:chemistry*; D018511:Systems Integration; D014512:Ureohydrolases / Q000737:chemistry*
chemical_list: D000376:Agmatine; C022488:putrescine oxidase; D000587:Oxidoreductases Acting on CH-NH Group Donors; D014512:Ureohydrolases; C019625:agmatinase