Method for assaying L-phenylalanine and L-phenylalanine sensor

• US 6,468,416 B1
• Filed: 01/12/2001
• Issued: 10/22/2002
• Est. Priority Date: 07/16/1998
• Status: Expired due to Fees

• Current Assignee: Sapporo Immuno Diagnostic Laboratory
• Original Assignee: Sapporo Immuno Diagnostic Laboratory
• Inventors: Nakamura, Kenji, Yokoyama, Toru, Shinozuka, Naoki
• Primary Examiner(s): Tung, T.
• Assistant Examiner(s): NOGUEROLA, ALEXANDER STEPHAN
• Application Number:
  US09/743,571
• Time in Patent Office: 648 Days
• Field of Search: 204/403, 204/403.06, 204/403.1, 204/403.14, 205/777.5
• US Class Current: 205/777.5
• CPC Class Codes: C12Q 1/005 involving specific analytes or enzymes including groups of enzymes, e.g. oxydases; C12Q1/004 takes precedence
• CPC Class Codes: C12Q 1/32 involving dehydrogenase

Abstract

An L-phenylalanine sensor wherein all of the reagents required in determining L-phenylalanine are integrated together, thereby enabling quick and convenient quantification without resort to any special equipment, devices or techniques. This sensor is fabricated by integrating L-phenylalanine dehydrogenase, oxidized nicotinamide adenine dinucleotide (NAD⁺) or oxidized nicotinamide adenine dinucleotide phosphate (NADP⁺) as a coenzyme and an electron mediator, which are employed as reagents, with an electrode system comprising at least a working electrode and a counter electrode. Also, a method of determining L-phenylalanine which comprises adding a sample containing L-phenylalanine to the above-described sensor and electrochemically quantitating L-phenylalanine is provided.

Claims

1. A method of determining L-phenylalanine comprising:

(1) adding a sample to an L-phenylalanine sensor composed of an electrode system which is formed by printing with the use of a conductive material and which comprises at least a working electrode made of a material mainly comprising carbon and a counter electrode formed on an insulating support, and a reagent reaction layer which is provided in a space of said electrode system comprising a working electrode and a counter electrode formed opposite to each other, and the reagent reaction layer contains as reagents at least L-phenylalanine dehydrogenase, NAD⁺ an or NADP⁺ as a coenzyme and phenazine as an electron mediator and which is fixed within said electrode system, and

(2) electrochemically quantifying L-phenylalanine.

2. An L-phenylalanine sensor having a structure composed of an electrode system which is formed by printing with the use of a conductive material and which comprises at least a working electrode made of a material mainly comprising carbon and a counter electrode formed on an insulating support, and a reagent reaction layer which is provided in a space of said electrode system comprising a working electrode and a counter electrode formed opposite to each other, and the reagent reaction layer contains as reagents at least L-phenylalanine dehydrogenase, NAD⁺ or NADP⁺ as a coenzyme and phenazine as an electron mediator and which is fixed within said electrode system.

3. An L-phenylalanine sensor as claimed in claim 2, wherein the reagent reaction layer comprises a hydrophilic absorbent carrier, and, in the electrode system comprising at least a working electrode and a counter electrode formed opposite to each other on an insulating support, said absorbent carrier is located in a part where an electrode reaction between these electrodes occurs and is partly protected from contact with the outside, said electrode system has a structure serving as at least a protective layer for said absorbent carrier, and said absorbent carrier providing a reaction layer for both of an enzyme reaction between a sample and the reaction reagents and the electrode reaction between an electron mediator and an electrode surface.