Table 2.

Measurements of zinc in endostatin

Protein	N terminus sequence	Endostatin concentration, μM	Zinc concentration, μM	Zinc/endostatin monomer
hE-EK	LHSHRD––	190	176	0.9
hE-Tryp	D––	180	14	0.07
hFc-hE		19	18	0.9
mFc-mE		90	79	0.9

Zinc determinations were performed by flame atomic absorption spectrometry with a Perkin–Elmer 2280 instrument. hE-EK, human endostatin derived from Fc construct by enterokinase digestion. hE-Tryp, human endostatin obtained from Fc construct by trypsin digestion. Fc-hE and Fc-mE denote human and murine Fc constructs, respectively. For more details, see Methods.