Table 2.

Purification of turkey coronavirus (TCoV) by ultracentrifugation of concentrated material through two times of continuous 40–60% (w/v) sucrose gradient

Step	Total volume (ml)	Total proteina (mg)	Total HA activity (unit)	Specific activityb (unit/mg)	Recoveryc(%)	Purification factord
3000×g supe	217	2170	34 720	16	100.0	1.0
60% cushion bandf	17	99	21 760	221	62.7	13.8
First gradientg	16	16	5216	320	15.0	20.0
Second gradienth	20	7	3260	476	9.4	29.8

^aProtein concentration was determined by the method of Lowry et al. (1951).

^bSpecific activity=total HA activity/total protein.

^cRecovery=total HA activity of e, f, g, or h/total HA activity of e.

^dPurification factor=specific activity of e, f, g, or h/specific activity of e.

^eSupernatants from centrifugation of infected turkey embryo intestinal homogenates at 3000×g for 10 min.

^fOpalescent band from ultracentrifugation of e at 100 000×g through a 5 ml cushion of 60% (w/v) sucrose solution for 1 h.

^gOpalescent band from ultracentrifugation of f at 100 000×g through a continuous 40–60% (w/v) sucrose gradient for 16 h.

^hOpalescent band from two times of ultracentrifugation of f at 100 000×g through continuous 40–60% (w/v) sucrose gradient for 16 h.