TABLE 1.

Metal content and PS-direct of PS preparations purified by different methods

Purification method (from barium-adsorbed plasma)	n	Zn/mol	Mg/mol	Ca/mol	IC50 (μM)a	PS-direct (1/IC50)
Immunoaffinity methods	7	1.4 ± 0.6	0.9 ± 0.6	8.5 ± 2.2	0.13 ± 0.06	7.7
MonoQ/EDTA + monoQ/Ca2+b	2	0.25 ± 0.05	0.7 ± 0.1	7.5 ± 0.3	≥2c	≤0.5
Commercial, unspecified	3	0.1 ± 0.1	0.6 ± 0.3	7.0 ± 2.2	>2	<0.5
Hexyl agarose, heparin sepharose	4	0.8 ± 0.5	0.9 ± 0.2	7.8 ± 1.9	0.14 ± 0.04	7.1

^a[PS] required to inhibit by 50% the rate of thrombin generated in the standardized prothrombinase assay. 

^bMonoQ chromatography: first with a salt gradient in the presence of EDTA; second, with a gradient of CaCl₂. Second preparation employed a similar Fast Flow Q resin, with EDTA, then CaCl₂ (16). 

^cHighest [PS] tested was 2 μM, which is 6-fold higher than the plasma [PS].