Proteinase-cleavage sites, targeting

CHAPTER 36, FIGURE 7 A group of structurally similar protein inhibitors of the serine proteinases known as SERPINS (SERine Proteinase INhibitors). The structure shown is human antithrombin. The reference SERPIN, a j-proteinase inhibitor or a. -antitrypsin contains -30% a helix (9 helices) and 40% sheet (5 3 sheets). Other members of the SERPIN family contain both additional helices and p sheets. The reactive center loop of antithrombin, residues 378-396, contains the reactive site residues Arg and Ser . Upon reaction with the target proteinase or after cleavage by the target proteinase (a reaction that inactivates the inhibitor without inactivating the proteinase), the reactive center loop folds between the S3 and S5 sheets. 

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