Method for measuring β-glucan, and β-glucan-binding protein for use in the method

1. A method for measuring β-glucan (hereinafter, abbreviated as “βG”), which comprises:

(1) contacting a sample with

protein 1 comprising an amino acid sequence shown in any one of SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8, and SEQ ID NO: 10, or an amino acid sequence having 95% or more of homology to the amino acid sequence shown in any one of SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8, and SEQ ID NO: 10, and having a β-glucan binding activity (hereinafter, abbreviated as “βG-binding protein 1”), and

protein 2 comprising an amino acid sequence shown in any one of SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8, and SEQ ID NO: 10, or an amino acid sequence having 95% or more of homology to the amino acid sequence shown in any one of SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8, and SEQ ID NO: 10, having a β-glucan binding activity (hereinafter, abbreviated as “βG-binding protein 2”), to form a complex of the βG-binding protein 1, βG in the sample and the βG-binding protein 2,

wherein the βG-binding protein 2 is labeled with a labeling substance;

(2) measuring a quantity of the labeling substance in the complex; and

(3) determining a βG concentration in the sample based on the quantity measured in (2).

2. The method of measurement according to claim 1 , wherein the βG-binding protein 1 is immobilized to an insoluble carrier.

3. The method of measurement according to claim 1 , wherein each of the βG-binding protein 1 and the βG-binding protein 2 is labeled with a labeling substances that is different from one another.

4. The method of measurement according to claim 1 , wherein the measurement comprises:

(1) contacting a sample with the βG-binding protein 1 to form a complex-1 of βG in the sample and the βG-binding protein 1;

(2) contacting the complex-1 with the βG-binding protein 2 which is labeled with a labeling substance, to form a complex-2 of the βG-binding protein 1, βG in the sample and the βG-binding protein 2;

(3) measuring quantity of the labeling substance in the complex-2; and

(4) determining a βG concentration in the sample based on the quantity of the complex-2 obtained.

5. The method of measurement according to claim 1 , wherein the measurement comprises:

(1) contacting a sample with βG-binding protein 1 which is immobilized to an insoluble carrier, to form a complex-1 of βG in the sample and the βG-binding protein 1 immobilized to the insoluble carrier;

(2) contacting the complex-1 with the βG-binding protein 2 which is labeled with a labeling substance, to form a complex-2 of the complex-1 and the labeled βG-binding protein 2;

(3) measuring quantity of the labeling substance in the complex-2; and

(4) determining βG concentration in the sample based on the quantity obtained.

6. The method of measurement according to claim 1 , wherein the βG-binding protein 1 and the βG-binding protein 2 are used without being immobilized to an insoluble carrier.

7. The method of measurement according to claim 6 , wherein after the complex is formed, the complex is separated from free βG-binding protein 1 and free βG-binding protein 2 by capillary electrophoresis.

8. A kit for measuring β-glucan comprising the followings as constituents:

(1) a reagent containing a protein 1 comprising an amino acid sequence shown in any one of SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8, and SEQ ID NO: 10, or an amino acid sequence having 95% or more of homology to the amino acid sequence shown in any of the SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8 and SEQ ID NO: 10, and having a β-glucan binding activity (hereinafter, abbreviated as “βG-binding protein 1”); and

(2) a reagent containing a protein 2 comprising an amino acid sequence shown in any one of SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8, and SEQ ID NO: 10, or an amino acid sequence having 95% or more of homology to the amino acid sequence shown in any one of the SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8, and SEQ ID NO: 10, and having a β-glucan binding activity. (hereinafter, abbreviated as “βG-binding protein 2”),

wherein the βG-binding protein 2 is labeled with a labeling substance.

9. The kit according to claim 8 , wherein the βG-binding protein 1 is immobilized to an insoluble carrier.

10. The kit according to claim 8 , wherein each of the βG-binding protein 1 and the βG-binding protein 2 is labeled with a labeling substance that is different from one another.

11. An isolated protein comprising an amino acid sequence identical to an amino acid sequence shown in any one of SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8, and SEQ ID NO: 10, or an amino acid sequence having 95% or more of homology to the amino acid sequence shown in any one of SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8, and SEQ ID NO: 10, and having a β-glucan binding activity.

12. A method for measuring βG comprising:

(1) contacting a sample with

βG-binding protein 1 comprising an amino acid sequence shown in any one of SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8, and SEQ ID NO: 10, or an amino acid sequence having 95% or more of homology to the amino acid sequence shown in any one of SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8, and SEQ ID NO: 10, and having a β-glucan binding activity (hereinafter, abbreviated as “βG-binding protein 1”), wherein the βG-binding protein 1 is immobilized to an insoluble carrier, and

βG-binding protein 2 comprising an amino acid sequence shown in any one of SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8, and SEQ ID NO: 10, or an amino acid sequence having 95% or more of homology to the amino acid sequence shown in any one of SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8, and SEQ ID NO: 10, and having a β-glucan binding activity (hereinafter, abbreviated as “βG-binding protein 2”), to form a complex of the βG-binding protein 1, βG in the sample and the βG-binding protein 2,

(2) measuring a quantity of the complex by a turbidimetric method, a nephelometric method, or a latex aggregation method; and

(3) determining a βG concentration in the sample based on the quantity measured in (2).

13. A method for measuring βG comprising:

(1) contacting a sample with

βG-binding protein 1 comprising an amino acid sequence shown in any one of SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8, and SEQ ID NO: 10, or an amino acid sequence having 95% or more of homology to the amino acid sequence shown in any one of SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8, and SEQ ID NO: 10, and having a β-glucan binding activity, and

βG-binding protein 2 comprising an amino acid sequence shown in any one of SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8, and SEQ ID NO: 10, or an amino acid sequence having 95% or more of homology to the amino acid sequence shown in any one of SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8, and SEQ ID NO: 10, and having a β-glucan binding activity, to form a complex of the βG-binding protein 1, βG in the sample and the βG-binding protein 2,

wherein the βG-binding protein 1 and βG-binding protein 2 are different each other, and

wherein at least one of the βG-binding protein 1 and the βG-binding protein 2 comprises an amino acid sequence shown in SEQ ID NO: 4 or SEQ ID NO: 10, or an amino acid sequence having 95% or more of homology to the amino acid sequence shown in SEQ ID NO: 4, or SEQ ID NO: 10, and having a β-glucan binding activity and peroxidase activity;

(2) measuring quantity of the complex by measuring a peroxidase activity derived from the βG-binding protein 1 and/or βG-binding protein 2; and

(3) determining a βG concentration in the sample based on the quantity.

14. The method of measurement according to claim 1 , wherein the βG-binding protein 1 is not immobilized to an insoluble carrier, and is not labeled with a labeling substance.

15. The kit according to claim 8 , wherein the βG-binding protein 1 and the βG-binding protein 2 are not immobilized to an insoluble carrier.

16. A kit for measuring β-glucan comprising the followings as constituents:

( 1 ) a reagent containing a protein 1 comprising an amino acid sequence shown in any one of SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8, and SEQ ID NO: 10, or an amino acid sequence having 95% or more of homology to the amino acid sequence shown in any one of SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8m, and SEQ ID NO: 10, and having a β-glucan binding activity, wherein the βG-binding protein 1 is immobilized to an insoluble carrier, and

(2) a reagent containing a protein 2 comprising an amino acid sequence shown in any one of SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8, and SEQ ID NO: 10, or an amino acid sequence having 95% or more of homology to the amino acid sequence shown in any one of SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8, and SEQ ID NO: 10, and having a β-glucan binding activity.

17. A kit for measuring βG comprising the followings as constituents:

(1) a reagent contacting a protein 1 comprising an amino acid sequence shown in any one of SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8, and SEQ ID NO: 10, or an amino acid sequence having 95% or more of homology to the amino acid sequence shown in any one of SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8, and SEQ ID NO: 10, and having a β-glucan binding activity, and

(2) a reagent containing a protein 2 comprising an amino acid sequence shown in any one of SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8, and SEQ ID NO: 10,or an amino acid sequence having 95% or more of homology to the amino acid sequence shown in any one of SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8, and SEQ ID NO: 10, and having a β-glucan binding activity,

wherein the βG-binding protein 1 and βG-binding protein 2 are different each other, and

wherein at least one of the βG-binding protein 1 and the βG-binding protein 2 comprises an amino acid sequence shown in SEQ ID NO: 4 or SEQ ID NO: 10, or an amino acid sequence having 95% or more of homology to the amino acid sequence shown in SEQ ID NO: 4, or SEQ ID NO: 10, and having a β-glucan binding activity and peroxidase activity.

18. The kit according to claim 8 , wherein the βG-binding protein 1 is not immobilized to an insoluble carrier, and is not lableled with a labeling substance.