DESCRIPTION

PROS1, also named as Vitamin K-dependent protein S, is a 676 amino acid protein, which contains 4 EGF-like domains, contains one Gla (gamma-carboxy-glutamate) domain and contains 2 laminin G-like domains. PROS1 as a secreted protein platelets alpha granules is expressed in plasma. PROS1 is a cofactor to activated protein C in the degradation of coagulation factors Va and VIIIa and helps to prevent coagulation and stimulating fibrinolysis.

PRINCIPLE OF THE ASSAY

Sandwich ELISA structure (Detection antibody labeled with HRP) A capture antibody is pre-coated onto the bottom of wells which binds to analyte of interest. A detection antibody labeled with HRP also binds to the analyte. TMB acts as the HRP substrate and the solution color will change from colorless to blue. A stop solution containing sulfuric acid turns solution yellow. The color intensity is proportional to the quantity of bound protein which is measurable at 450 nm with the correction wavelength set at 630 nm.

PRECISION

Intra-assay Precision (Precision within an assay) Three samples of known concentration were tested 8 times on one plate to assess intra-assay precision. Inter-assay Precision (Precision between assays) Three samples of known concentration were tested in 16 separate assays to assess inter-assay precision.

Intra-assay Precision

Sample	n	Mean (ng/mL)	SD	CV%
1	8	22.97	0.72	3.15
2	8	5.11	0.21	4.14
3	8	2.82	0.25	8.99

Inter-assay Precision

Sample	n	Mean (ng/mL)	SD	CV%
1	16	23.18	1.26	5.44
2	16	4.94	0.27	5.46
3	16	2.87	0.24	8.29

RECOVERY

The recovery of human PROS1 spiked to three different levels throughout the range of the assay in cell lysate was evaluated.

Sample Type		Average% of Expected	Range (%)
Cell lysate	1:16	101	89-119

LINEARITY

To assess the linearity of the assay, samples were diluted with the appropriate Sample Diluent to produce samples with values within the dynamic range of the assay.

		Cell lysate
1:2	Average% of Expected	100
	Range (%)	-
1:4	Average% of Expected	83
	Range (%)	81-87
1:8	Average% of Expected	82
	Range (%)	80-84
1:16	Average% of Expected	93
	Range (%)	88-95

CALIBRATION

This immunoassay is calibrated against a highly purified recombinant human Human PROS1 Sandwich ELISA Kit produced at Sunlong Medical™.