Table 1.

Relative Activities of SpA Forms

SpA form		MW	No. of domains	Fab-binding	Fc-binding
		kD		M	M
SpA	Native	42	5	2 × 10−6	4 × 10−7
MSpA	Iodinated	42	5	1 × 10−5	ND
DD′	Native	11	1	1 × 10−2	2 × 10−4
DimDD′	L17D I31A	24	2	1 × 10−2	ND
TetmDD′	L17D I31A	37	4	5 × 10−3	ND

MW, molecular mass.