title: A spider-derived Kunitz-type serine protease inhibitor that acts as a plasmin inhibitor and an elastase inhibitor.
abstract: Kunitz-type serine protease inhibitors are involved in various physiological processes, such as ion channel blocking, blood coagulation, fibrinolysis, and inflammation. While spider-derived Kunitz-type proteins show activity in trypsin or chymotrypsin inhibition and K(+) channel blocking, no additional role for these proteins has been elucidated. In this study, we identified the first spider (Araneus ventricosus) Kunitz-type serine protease inhibitor (AvKTI) that acts as a plasmin inhibitor and an elastase inhibitor. AvKTI possesses a Kunitz domain consisting of a 57-amino-acid mature peptide that displays features consistent with Kunitz-type inhibitors, including six conserved cysteine residues and a P1 lysine residue. Recombinant AvKTI, expressed in baculovirus-infected insect cells, showed a dual inhibitory activity against trypsin (K(i) 7.34 nM) and chymotrypsin (K(i) 37.75 nM), defining a role for AvKTI as a spider-derived Kunitz-type serine protease inhibitor. Additionally, AvKTI showed no detectable inhibitory effects on factor Xa, thrombin, or tissue plasminogen activator; however, AvKTI inhibited plasmin (K(i) 4.89 nM) and neutrophil elastase (K(i) 169.07 nM), indicating that it acts as an antifibrinolytic factor and an antielastolytic factor. These findings constitute molecular evidence that AvKTI acts as a plasmin inhibitor and an elastase inhibitor and also provide a novel view of the functions of a spider-derived Kunitz-type serine protease inhibitor.
authors: College of Natural Resources and Life Science, Dong-A University, Busan, Republic of Korea.
authors: Hu
authors: H
authors: Wan
authors: Kwang Sik
authors: KS
authors: Lee
authors: Bo Yeon
authors: BY
authors: Kim
authors: Feng Ming
authors: FM
authors: Zou
authors: Hyung Joo
authors: HJ
authors: Yoon
authors: Yeon Ho
authors: YH
authors: Je
authors: Jianhong
authors: J
authors: Li
authors: Byung Rae
authors: BR
authors: Jin
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000933:Antifibrinolytic Agents / Q000737:chemistry* / Q000378:metabolism; D007611:Aprotinin / Q000737:chemistry* / Q000235:genetics; D060829:Arthropod Proteins / Q000737:chemistry* / Q000235:genetics; D016367:Baculoviridae / Q000235:genetics; D002918:Chymotrypsin / Q000037:antagonists & inhibitors / Q000378:metabolism; D017124:Conserved Sequence; D015951:Factor Xa / Q000737:chemistry; D005341:Fibrinolysin / Q000037:antagonists & inhibitors* / Q000737:chemistry; D015870:Gene Expression; D008969:Molecular Sequence Data; D010196:Pancreatic Elastase / Q000037:antagonists & inhibitors* / Q000737:chemistry; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry* / Q000235:genetics; D016415:Sequence Alignment; D015842:Serine Proteinase Inhibitors / Q000737:chemistry* / Q000235:genetics; D013112:Spiders / Q000737:chemistry* / Q000378:metabolism; D013917:Thrombin / Q000737:chemistry; D010959:Tissue Plasminogen Activator / Q000737:chemistry; D014357:Trypsin / Q000378:metabolism; D014361:Trypsin Inhibitors / Q000737:chemistry* / Q000235:genetics
chemical_list: D000933:Antifibrinolytic Agents; D060829:Arthropod Proteins; D011994:Recombinant Proteins; D015842:Serine Proteinase Inhibitors; D014361:Trypsin Inhibitors; C098973:recombinant Kunitz protease inhibitor; D007611:Aprotinin; D002918:Chymotrypsin; D010196:Pancreatic Elastase; D014357:Trypsin; D013917:Thrombin; D015951:Factor Xa; D010959:Tissue Plasminogen Activator; D005341:Fibrinolysin