Mechanisms of Macromolecular Protease Inhibitors
ABSTRACT Relatively few design principles underlie the inhibition mechanisms of macromolecular protease inhibitors. These inhibitors tend to compete with substrate binding either through direct competition or deformation of the protease active site; they gain potency and specificity by burying a large surface area and through contacts with specific exosites. Protein engineering has allowed both potency and specificity to be modified.
Full-textDOI: · Available from: Charles S Craik, Aug 13, 2015
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- "Recently, the Kunitz-type serine protease inhibitor HAI-2 (hepatocyte growth factor activator inhibitor type 2) has been shown to inhibit the proteolytic activity of MT-2 . Since Kunitz-type inhibitors bind to their target proteases in a substrate-like manner , HAI-2 can also be considered to bear a processing site attacked by MT-2. For instance, Kunitz domain I exhibited two critical Arg residues which might be recognized by MT-2. "
ABSTRACT: Human matriptase-2 is an enzyme that belongs to the family of type II transmembrane serine proteases. So far there is a limited knowledge regarding its specificity and protein substrate(s). One of the identified natural substrates is hemojuvelin, a protein involved in the control of iron homeostasis. In this work, we describe the synthesis and evaluation of internal quenched substrates using a combinatorial approach. The iterative deconvolution of two libraries to define the specificity of matriptase-2 yielded to the identification of the substrate ABZ-Ile-Arg-Ala-Arg-Ser-Ala-Gly-Tyr(3-NO2)-NH2 with a kcat/Km value of 4.5×10(5) M(-1)×s(-1), i.e. the highest specificity constant reported so far for matriptase-2.Biochimie 10/2013; 97(1). DOI:10.1016/j.biochi.2013.10.001 · 3.12 Impact Factor
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ABSTRACT: Semliki Forest virus (SFV) is a member of the Alphavirus genus, which produces its replicase proteins in the form of a nonstructural (ns) polyprotein precursor P1234. The maturation of the replicase occurs in a temporally controlled manner by protease activity of nsP2. The template preference and enzymatic capabilities of the alphaviral replication complex have a very important connection with its composition, which is irreversibly altered by proteolysis. The final cleavage of the 2/3 site in the ns polyprotein apparently leads to significant rearrangements within the replication complex and thus denotes the "point of no return" for viral replication progression. Numerous studies have devised rules for when and how ns protease acts, but how the alphaviral 2/3 site is recognized remained largely unexplained. In contrast to the other two cleavage sites within the ns polyprotein, the 2/3 site evidently lacks primary sequence elements in the vicinity of the scissile bond sufficient for specific protease recognition. In this study, we sought to investigate the molecular details of the regulation of the 2/3 site processing in the SFV ns polyprotein. We present evidence that correct macromolecular assembly, presumably strengthened by exosite interactions rather than the functionality of the individual nsP2 protease, is the driving force for specific substrate targeting. We conclude that structural elements within the macrodomain of nsP3 are used for precise positioning of a substrate recognition sequence at the catalytic center of the protease and that this process is coordinated by the exact N-terminal end of nsP2, thus representing a unique regulation mechanism used by alphaviruses.Journal of Virology 01/2012; 86(1):553-65. DOI:10.1128/JVI.05195-11 · 4.65 Impact Factor
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ABSTRACT: Parasitic organisms are constantly challenged by the defence mechanisms of their respective hosts, which often depend on serine protease activities. Consequently, protease inhibitors such as those belonging to the serpin superfamily have emerged as protective elements that support the survival of the parasites. This report describes the crystal structure of ShSPI, a serpin from the trematode Schistosoma haematobium. The protein is exposed on the surface of invading cercaria as well as of adult worms, suggesting its involvement in the parasite-host interaction. While generally conforming to the well established serpin fold, the structure reveals several distinctive features, mostly concerning the helical subdomain of the protein. It is proposed that these peculiarities are related to the unique biological properties of a small serpin subfamily which is conserved among pathogenic schistosomes.Acta Crystallographica Section D Biological Crystallography 06/2012; 68(Pt 6):686-94. DOI:10.1107/S0907444912008372 · 7.23 Impact Factor