Abstract
The mouse protective antigen (MPA) and histamine-sensitizing factor (HSF) in sonic extracts of B. pertussis resembled one another in being much less sensitive to destruction by sodium periodate at 1 °C than was the serological activity of the pertussis lipopolysaccharide (LP). Whereas the latter was more than 96% inactivated by 2 hours in 0.01 M periodate at pH 7.4 at 1°, MPA and HSF underwent, on average, 48% and 32% inactivation respectively. Glucose and serine similarly treated with periodate were completely oxidized; trypsin underwent 44% inactivation, but insulin, tetanus toxin, and the peptide cystinyldiglycine were not significantly attacked. These results are interpreted as supporting the view that MPA and HSF probably do not contain functionally essential carbohydrate and, from this and other evidence, are probably protein in nature.