Assay systems using more than one enzyme

• US 4,758,323 A
• Filed: 05/07/1984
• Issued: 07/19/1988
• Est. Priority Date: 05/05/1983
• Status: Expired due to Term

• Current Assignee: Generics International Incorporated (Endo International PLC)
• Original Assignee: Generics International Incorporated (Endo International PLC)
• Inventors: Davis, Graham, Hill, Hugh A. O.
• Primary Examiner(s): TUNG, TA HSUNG
• Application Number:
  US06/607,698
• Time in Patent Office: 1,534 Days
• Field of Search: 435/26, 435/288, 435/817, 204/403, 204/1 E
• US Class Current: 204/403.14
• CPC Class Codes: A61B 5/1486 using enzyme electrodes, e.g. with immobilised oxidase
• CPC Class Codes: A61B 5/6848 Needles
• CPC Class Codes: C12Q 1/001 Enzyme electrodes
• CPC Class Codes: C12Q 1/004 mediator-assisted
• CPC Class Codes: Y10S 435/817 Enzyme or microbe electrode

Abstract

This specification discloses methods of detection or measurement of an enzyme or of its specific substrate, and sensors used in such methods. The present invention is concerned with a multi-enzyme system, and the specification discloses, as one aspect of the invention a method of assay in which an electrode poised at a suitable potential is contacted with a system comprising a first enzyme, a cofactor linked with said enzyme and a mediator compound which transfers charge to the electrode from the first enzyme when its electrical state is changed by reaction of cofactor material.

The cofactor may be NAD, NADP (both collectively referred to herein as NAD(P)), cAMP, ATP, GTP, TTP, or CTP.

The specification particularly illustrates a method of assay in which an electrode (1) poised at a suitable potential is contacted with a system comprising a first enzyme E₁ a nicotinamide adenine dinucleotide compound N linked with said enzyme E₁ and a mediator compound F which transfers charge to the electrodes from the first enzyme when its electrical state is changed by a NAD(P) NAD(P)H reaction. The NAD compound may act as a "bridge" between the said enzyme/mediator system and further NAD utilizing enzyme E2.

Claims

1. A sensor electrode having a coating consisting essentially of a ferrocene mediator, gluathione reductase and a nicotinamide adenine dinucleotide.

2. A sensor electrode as claimed in claim 1 in which the ferrocene is 1,1'"'"'-dimethylferrocene.

3. A sensor electrode as claimed in claim 1 in which the ferrocene and enzyme are chemically linked together.

4. The sensor electrode of claim 1 wherein said electrode is substantially free from substrate for said enzyme.

5. A sensor electrode having a coating consisting essentially of a ferrocene mediator, diaphorase, and a nicotinamide adenine dinucleotide.

6. A sensor electrode as claimed in claim 5 in which the ferrocene is 1,1'"'"'-dimethylferrocene.

7. A sensor electrode as claimed in claim 5 in which the ferrocene and enzyme are chemically linked together.