| SPA

Protein A is a 42 kDa surface protein originally found in the cell wall of the bacteria Staphylococcus aureus. Its regulation is controlled by DNA topology, cellular osmolarity, and a two-component system called ArlS-ArlR. It has found use in biochemical research because of its ability to bind immunoglobulins. It is composed of five homologous Ig-binding domains that fold into a three-helix bundle. Each domain is able to bind proteins from many mammalian species, most notably IgGs.
 

| Typical data

As the OD values of the standard curve may vary according to the conditions of the actual assay performance (e.g. operator, pipetting technique, wash technique or temperature effects), the operator should establish a standard curve for each test. Typical standard curve and data are provided below for reference only.

 

Concentration (pg/mL)	2000	1000	500	250	125	62.5	31.25	0
OD	2.67	1.7	0.97	0.56	0.31	0.2	0.14	0.07
Corrected OD	2.6	1.63	0.9	0.49	0.24	0.13	0.07	-

 

| Repeatability

Intra-assay Precision (Precision within an assay)：CV% < 10%; Inter-assay Precision (Precision between assays)：CV% < 10%
 

| Recovery

The recovery of SPA spiked at three different levels in samples throughout the range of the assay was evaluated in various matrices.

 

Sample Type	Range(%)	Average Recovery(%)
Serum(n=8)	81-101	96
Plasma(n=8)	92-106	102
Cell Culture Supernates(n=8)	97-108	105

 

| Linearity

Samples were spiked with high concentrations of SPA and diluted with Universal Diluent to produce samples with values within the range of the assay.

 

		Serum(n=4)	Plasma(n=4)	Cell Culture Supernates(n=4)
1 : 2	Range (%)	83-95	87-96	90-110
	Average (%)	91	92	96
1 : 4	Range (%)	89-104	87-108	105-115
	Average (%)	93	98	110