Preparation of ¹⁴C-Labeled Endotoxin and Endotoxic Glycolipid (EGL)

Abstract

LPS can be labeled by ⁵¹Cr which forms an undefined complex with the toxic components of the structure (Braude et al., 1955). Such compounds were used extensively in studying the fate of ⁵¹Cr-LPS, under normal as well as pathologic conditions. A shortcoming of this otherwise excellent procedure is that the ⁵¹Cr label is detected by it with or without the carrier LPS molecule, which means that the presence of the label not necessarily indicates the presence of the entire complex. The procedure des-, cribed here was used in our laboratory by Dr. Chen-lo H. Chen and it applies covalently bound ¹⁴C which is incorporated into the entire bacterial cell through biosynthesis. Extraction and purification of the labeled endotoxic LPS or EGL is carried out as described in Exercise 21.