Table 1. Results of ¹⁵N, ¹³C-labeled RGD-Hirudin Purification.

Step	Volume(mL)	Total ProteinConcentration(mg/mL)	Total Protein(mg)	Total Anti-ThrombinActivity (ATU)	Specific Activity(ATU/mg)	ActivityRecovery (%)
Supernatant	1600	0.75	1200	9,000,000	7500	100
After ultrafiltration	400	2.6	1040	7,800,000	7500	86.7
After Gel filtration	1000	0.5	500	4,000,000	8000	44.4
After anion exchange	200	1.25	250	2,500,000	10000	27.8