Isolation of a glycoprotein from Mycoplasma pneumoniae membranes

A glycoprotein was detected in Mycoplasma pneumoniae membranes. Its apparent molecular weight was about 60,000, as observed by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. It corresponded to the single band that was detected on the gels by the carbohydrate stain, periodic acid-Schiff reagent. The intensity of this stained band varied for membranes derived from cells harvested between 4 and 10 days, with maximal intensity found for cells grown for 6 days. The carbohydrate-containing polypeptide was extracted with lithium diiodosalicylate. The extracted fraction consisted of about 80 to 90% amino acids (mainly glycine and histidine) and about 7% carbohydrates (mainly glucose, galactose, and glucosamine). The fraction was immunologically active, as indicated by the complement fixation and precipitin tests with antisera against whole cells, membranes, and membrane proteins.