Figure 4.

Substrate specificity of the spleen homogenate activity. (A) Nitrotyrosine-containing proteins were analyzed with Western immunoblotting after nitrated proteins (4.2 μg) (see text) were incubated without (lane 1) or with spleen homogenate (50 μg of protein) from a LPS-treated rat (lane 2). To examine endogenous nitrotyrosine-containing proteins in spleen homogenate, the spleen homogenate was also incubated without added nitrated proteins (lane 3). The arrowheads indicate the proteins with covalently coupled nitrotyrosine (116, 66, 32, and 14 kDa). (B) Coomassie brilliant blue staining of a duplicate gel. Lanes are the same as in A.