6o1g
Full length human plasma kallikrein with inhibitor
Structural highlights
Disease[KLKB1_HUMAN] Defects in KLKB1 are the cause of prekallikrein deficiency (PKK deficiency) [MIM:612423]; also known as Fletcher factor deficiency. This disorder is a blood coagulation defect. Function[KLKB1_HUMAN] The enzyme cleaves Lys-Arg and Arg-Ser bonds. It activates, in a reciprocal reaction, factor XII after its binding to a negatively charged surface. It also releases bradykinin from HMW kininogen and may also play a role in the renin-angiotensin system by converting prorenin into renin. Publication Abstract from PubMedPlasma kallikrein (pKal) is a serine protease responsible for cleaving high-molecular-weight kininogen to produce the pro-inflammatory peptide, bradykinin. Unregulated pKal activity can lead to hereditary angioedema (HAE) following excess bradykinin release. HAE attacks can lead to a compromised airway that can be life threatening. As there are limited agents for prophylaxis of HAE attacks, there is a high unmet need for a therapeutic agent for regulating pKal with a high degree of specificity. Here we present crystal structures of both full-length and the protease domain of pKal, bound to two very distinct classes of small-molecule inhibitors: compound 1, and BCX4161. Both inhibitors demonstrate low nM inhibitory potency for pKal and varying specificity for related serine proteases. Compound 1 utilizes a surprising mode of interaction and upon binding results in a rearrangement of the binding pocket. Co-crystal structures of pKal describes why this class of small-molecule inhibitor is potent. Lack of conservation in surrounding residues explains the approximately 10,000-fold specificity over structurally similar proteases, as shown by in vitro protease inhibition data. Structural information, combined with biochemical and enzymatic analyses, provides a novel scaffold for the design of targeted oral small molecule inhibitors of pKal for treatment of HAE and other diseases resulting from unregulated plasma kallikrein activity. Structures of full-length plasma kallikrein bound to highly specific inhibitors describe a new mode of targeted inhibition.,Partridge JR, Choy RM, Silva-Garcia A, Yu C, Li Z, Sham H, Metcalf B J Struct Biol. 2019 Mar 12. pii: S1047-8477(19)30046-2. doi:, 10.1016/j.jsb.2019.03.001. PMID:30876891[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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