Staphylococcal protein A (SPA) is a surface protein existing in the cell wall of Staphylococcus. SPA mainly exists in some SAs, but not in Staphylococcus epidermidis (Staphypider. Idies.se.se) and Staphylococcus saprophyticus (Stephy saprophytic bacteria). 55).

SPA contains nitrogen 14- 16%, which is a single and multi-slave chain, and contains about 395 amino acids (AA), including bright, preserved, sour, sweet, C, silk, cereals, asparagus and lysine. Each multi-skin chain contains four highly homologous Fc binding regions, namely D, A, B and C, and each region consists of about 55-62 AA residues.

Extended data

Immunological characteristics:

It has the characteristic of binding with Fc segment of G molecule in various animal serum. SPA can produce precipitation lines with the sera of many mammals (pigs, guinea pigs, mice, dogs and monkeys, etc.). ) or 1gG, in which the titer of pig serum was the highest, and no precipitation line was formed for cattle, horses and sheep. Fish, amphibians, reptiles and birds can't react with Bigger.

SPA can bind to Fc fragments of IgG in humans and many mammals. The combination of SPA and IgG has many biological activities, such as anti-phagocytosis, promoting cell division, causing hypersensitivity and damaging platelets.

On the other hand, the Fab segment of IgG (except IgG 3) can still specifically bind antigen after binding to IgGFc in SPA, which can be used for cooperative agglutination test to detect various bacterial antigens or antigen-antibody complexes. SPA is also a B cell mitogen, which can activate and proliferate polyclonal B cells.

Baidu Encyclopedia-Staphylococcus A Protein