Ž . Immunopharmacology 45 1999 171–177 www.elsevier.comrlocaterimmpharm A double headed serine proteinase inhibitor — human plasma kallikrein and elastase inhibitor — from Boophilus microplus larvae Aparecida S. Tanaka a, ) , Renato Andreotti b , Alberto Gomes b , Ricardo J.S. Torquato a , Misako U. Sampaio a , Claudio A.M. Sampaio a a Departamento de Bioquımica, UNIFESP-EPM, Rua 3 de Maio 100, 04044-020, Sao Paulo, SP, Brazil ´ b EMBRAPA-CNPGC, C. Grande, MS, Brazil Accepted 4 March 1999 Abstract Preying on cattle, the hard tick Boophilus microplus causes heavy economical losses to Brazil. Tick proteins are a good Ž . target to be used as tools for tick control. Serine protease inhibitors from B. microplus larvae BmTI were preliminarily characterized. One-week-old larvae were the source of a 2% protein solution in 5 mM Tris–HCl, 20 mM NaCl, pH 7.4. The inhibitors were purified by affinity chromatography on trypsin-Sepharose, and ion-exchange chromatography on Resource Q Ž column, and they separated in two major active peaks, corresponding to 10-kDa and 18-kDa proteins BmTI-B and BmTI-A, . respectively . Both purified proteins inhibited trypsin with K of 0.3 and 3.0 nM, respectively, but only the 18-kDa protein i Ž . Ž . Ž . inhibited elastase K 1.4 nM and plasma kallikrein K 120 nM . BmTI-A did not change prothrombin time PT and i i Ž . Ž . thrombin time TT , but it increased activated partial thromboplastin time APTT was dose-dependent. The partial amino Ž . acid sequence indicated that BmTI-A belongs to the bovine pancreatic trypsin inhibitor BPTI -Kunitz type inhibitor family. Ž . These inhibitors by their properties play a role in the feeding process of the tick. Development of antibodies against these proteins may be used to impair the normal feeding and consequently, the parasite would be no longer viable. q 1999 Elsevier Science B.V. All rights reserved. Keywords: Serine proteinase inhibitors; Tick; Blood coagulation; APTT 1. Introduction Ž . The tick Boophilus microplus is an important cattle parasite in South and Central America, Aus- tralia, Asia and Africa. One cause of death in cattle is the heavy infestation by ticks, and the transmission ) Corresponding author. Tel: q55-11-576-4444; fax: q55-11- 572-3006; e-mail: tanaka.bioq@epm.br of diseases such as anaplasmosis and babesiosis. Tick control can be achieved by application of chem- ical products, but the development of resistance to many acaricides has created problems in this ap- Ž . proach Roulstan et al., 1981 . Cattle acquire partial immunity to the ectoparasite after extensive natural exposure, due largely to an immediate hypersensi- tivity reaction to the tick which is, nevertheless, unable to prevent serious losses in cattle production Ž . Rodrıguez et al., 1994 . Recently tick control has ´ 0162-3109r99r$ - see front matter q 1999 Elsevier Science B.V. All rights reserved. Ž . PII: S0162-3109 99 00074-0