Characterization of the h1 protein antigen from Staphylococcus aureus 17A

The h1 protein antigen from Staphylococcus aureus 17 A was found to be present associated with the cell wall as well as freely in the growth medium. The two forms did not differ in size or immunological properties. Only lytic or proteolytic enzymes could release h1 from the isolated cell wall. The molecule was readily broken down by trypsin to discrete fragments which all had common antigenic determinants. The results suggest that the antigen is covalently linked in the cell wall and that its structure might be similar to that of protein A.