Figure 7

G27 LPS species are quantitatively recovered in purified preparations, and respond to cholesterol in the growth medium. In two independent experiments, parallel cultures of H. pylori strain G27 were grown overnight in defined medium without (-) or with (+) 50 μg/ml cholesterol. Cell lysates were digested with proteinase K, and portions of each lysate were further purified by hot phenol extraction and alcohol precipitation. Aliquots taken after digest only or after the extraction/precipitation procedure were resolved on a 15% urea gel. Each lane represents an amount of sample material derived from an equivalent amount of the initial cell lysate (2 μg protein). The reference lane contains 400 ng of LPS from E. coli O111:B4 as a silver staining control. No bands were selectively gained or lost in the workup following proteolytic digestion.