3.4.21.47	Cleavage of Arg-/-Ser bond in complement component C3 alpha-chain to yield C3a and C3b, and Arg-/- bond in complement component C5 alpha-chain to yield C5a and C5b	factor B binding to C3b forms an open activation state of C3bB. Factor D specifically binds the open conformation of factor B through a site distant from the catalytic center and is activated by the substrate, which displaces factor D's self-inhibitory loop. This concerted proteolytic mechanism, which is cofactor-dependent and substrate-induced, restricts complement amplification to C3b-tagged target cells	718398	
3.4.21.47	Cleavage of Arg-/-Ser bond in complement component C3 alpha-chain to yield C3a and C3b, and Arg-/- bond in complement component C5 alpha-chain to yield C5a and C5b	the enzyme is a bimolecular complex of complement fragment Bb with either C3b or cobra venom factor. Bb contains the active site. Bb is formed by cleavage of proenzyme factor B by factor D. Cleavage of complement component C5 requires additional C3b which binds C5 and renders it susceptible to cleavage by C3b,Bb complex, , intermediate catalytic mechanism and a kinetic mechanism of a tetra uni ping pong bi bi reaction reduced to a uni bi reaction	36596