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The effect of trypsin cleavage on the structure and function of human C4
Author(s) -
Yman Ingrid Malmheden,
Lundwall Åke,
Stålenheim Gunnemar,
Sjöquist John
Publication year - 1981
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(81)81157-x
Subject(s) - trypsin , cleavage (geology) , chemistry , structure function , biochemistry , biology , enzyme , physics , paleontology , fracture (geology) , particle physics
When activated by Cis, C4 is cleaved, releasing a small peptide, C4a, of M, 10 000 [5,6].This peptide is spasmogenic for guinea pig ileum and tachyphylactic for human C3a anaphylatoxin [7]. The rest of the molecule after Cis cleavage, i.e., C4b, can bind to the cell surface via a labile binding site. C4b, on the cell surface or in solution, is easily cleaved by the C4b inactivator (C4bINA) [8] in the presence of CCbinding protein (C4bp) [9,10]. Two fragments are produced, namely C4d, a fragment of the a-chain, and C4c, which consists of the residual a-chain and the intact /?and y-chains. Fresh frozen ACD-plasma from healthy adult, purchased from the University Hospital (Uppsala) served as the origin for preparation of complement components. Sheep erythrocytes and rabbit antisheep hemolysin were from the National Bacteriological Lab. (Stockholm). D,L-Dithiothreitol (DTT) was purchased from Sigma (St Louis MO). L-(Tosylamide-2phenyl-ethyl-chloromethyl-ketone)-treated trypsin with spec. act. 224 units/mg and soybean trypsin inhibitor (SBTI) were purchased from Worthington Biochemical Corp. (Freehold NJ).