VALUE-ASSIGNED SOLUTIONS OF LIPOPROTEIN-ASSOCIATED PHOSPHOLIPASE A2 HAVING A LONG SHELF-LIFE
Value-assigned solutions having predetermined concentrations of recombinant Lp-PLA2 are described herein. In particular, described herein are solutions of rLp-PLA2 that are stable for an extended period of time. Kits and assays include these calibration solutions, as well as methods of making and using them are described.
1 . A value-assigned solution of lipoprotein-associated phospholipase A2 (Lp-PLA2) for use with an Lp-PLA2 assay as a control, standard, calibrator or re-calibrator, the value-assigned solution having a shelf-life of greater than 4 months, the value-assigned solution comprising:
a first predetermined concentration of a recombinant Lp-PLA2 in
a low-salt buffer solution having a salt concentration below about 1 M,
wherein the low-salt buffer solution comprises a detergent forming a plurality of micelles that stabilize the recombinant Lp-PLA2.
2 . The value-assigned solution of claim 1 , further comprising a second detergent to prevent aggregation of the recombinant Lp-PLA2.
3 . The value-assigned solution of claim 2 , wherein the second detergent comprises a non-ionic detergent.
4 . The value-assigned solution of claim 2 , wherein the second detergent comprises a polysorbate detergent.
5 . The value-assigned solution of claim 1 , wherein the detergent is above a critical micelle concentration (CMC).
6 . The value-assigned solution of claim 1 , wherein the detergent comprises a cholate detergent.
7 . The value-assigned solution of claim 1 , wherein the detergent comprises CHAPS.
8 . The value-assigned solution of claim 1 , wherein the low-salt buffer solution comprises a non-chaotropic salt.
9 . The value-assigned solution of claim 1 , wherein the low-salt buffer solution comprises one or more of: NaCl and an acetate salt.
10 . The value-assigned solution of claim 1 , wherein the low-salt buffer solution includes a protein buffered matrix.
11 . The value-assigned solution of claim 1 , wherein the low-salt buffer solution includes a pH buffer.
12 . The value-assigned solution of claim 1 , wherein the low-salt buffer solution includes Tris as a pH buffer.
13 . A value-assigned solution of lipoprotein-associated phospholipase A2 (Lp-PLA2) for use with an Lp-PLA2 assay as a control, standard, calibrator or re-calibrator, the value-assigned solution having a shelf-life of greater than 4 months, the value-assigned solution comprising:
a first predetermined concentration of a recombinant Lp-PLA2 in
a low-salt buffer solution having a salt concentration below about 1 M,
wherein the low-salt buffer solution comprises a detergent forming a plurality of micelles that stabilize the recombinant Lp-PLA2 and a second detergent to prevent aggregation of the recombinant Lp-PLA2.
14 . A lipoprotein-associated phospholipase A2 (Lp-PLA2) kit for use with an Lp-PLA2 assay, the kit having a shelf-life of greater than 4 months, the kit comprising:
a first value-assigned solution comprising a first predetermined concentration of a recombinant Lp-PLA2 in a first low-salt buffer solution having a salt concentration below about 1 M, wherein the first buffer solution comprises a cholate detergent forming a plurality of micelles that stabilizes the recombinant Lp-PLA2, a protein buffered matrix, a pH buffer and a preservative; and
a second value-assigned solution comprising a second low-salt buffer solution having a salt concentration below about 1 M, wherein the second buffer solution comprises a plurality of micelles of the cholate detergent.
15 . The kit of claim 14 , wherein the cholate detergent comprises CHAPS.
16 . The kit of claim 14 , wherein the preservative comprises sodium azide.
17 . The kit of claim 14 , wherein the protein buffered matrix comprises bovine serum albumin (BSA).
18 . The kit of claim 14 , wherein the first buffer solution comprises a second detergent to prevent aggregation of the recombinant Lp-PLA2.
19 . The kit of claim 14 , wherein the second buffer solution comprises a second detergent comprising a polysorbate detergent.
20 . A lipoprotein-associated phospholipase A2 (Lp-PLA2) assay having recombinant value-assigned solutions having a shelf-life of more than 4 months, the assay comprising:
a plurality of value-assigned solutions each comprising a predetermined concentration of a recombinant Lp-PLA2 in a low-salt buffer solution having a salt concentration below about 1 M, wherein the buffer solution comprises a cholate detergent forming a plurality of micelles that stabilizes the recombinant Lp-PLA2;
a solution comprising an agent that interacts with Lp-PLA2 to produce a detectable signal; and
a wash buffer.
21 . The assay of claim 20 , further comprising a solid phase support configured to bind Lp-PLA2.
22 . The assay of claim 20 , wherein the agent comprises a report antibody specific to Lp-PLA2.
23 . The assay of claim 20 , wherein the low-salt buffer further comprises a second detergent to prevent aggregation of the recombinant Lp-PLA2.
24 . The assay of claim 20 , wherein the cholate detergent is above a critical micelle concentration (CMC) for the cholate detergent.
25 . The assay of claim 20 , wherein the cholate detergent comprises CHAPS.
26 . The assay of claim 20 , wherein the low-salt buffer solution comprises a non-chaotropic salt.
27 . The assay of claim 20 , wherein the low-salt buffer solution includes a protein buffered matrix.
28 . The assay of claim 20 , wherein the low-salt buffer solution includes bovine serum albumin (BSA) as a protein buffered matrix.
29 . The assay of claim 20 , wherein the low-salt buffer solution includes a pH buffer.