title: Heparin modulates the endopeptidase activity of Leishmania mexicana cysteine protease cathepsin L-Like rCPB2.8.
abstract: BACKGROUND
  Cysteine protease B is considered crucial for the survival and infectivity of the Leishmania in its human host. Several microorganism pathogens bind to the heparin-like glycosaminoglycans chains of proteoglycans at host-cell surface to promote their attachment and internalization. Here, we have investigated the influence of heparin upon Leishmania mexicana cysteine protease rCPB2.8 activity.
  
  
  RESULTS
  THE DATA ANALYSIS REVEALED THAT THE PRESENCE OF HEPARIN AFFECTS ALL STEPS OF THE ENZYME REACTION: (i) it decreases 3.5-fold the k 1 and 4.0-fold the k -1, (ii) it affects the acyl-enzyme accumulation with pronounced decrease in k 2 (2.7-fold), and also decrease in k 3 (3.5-fold). The large values of ΔG  =  12 kJ/mol for the association and dissociation steps indicate substantial structural strains linked to the formation/dissociation of the ES complex in the presence of heparin, which underscore a conformational change that prevents the diffusion of substrate in the rCPB2.8 active site. Binding to heparin also significantly decreases the α-helix content of the rCPB2.8 and perturbs the intrinsic fluorescence emission of the enzyme. The data strongly suggest that heparin is altering the ionization of catalytic (Cys(25))-S(-)/(His(163))-Im(+) H ion pair of the rCPB2.8. Moreover, the interaction of heparin with the N-terminal pro-region of rCPB2.8 significantly decreased its inhibitory activity against the mature enzyme.
  
  
  CONCLUSIONS
  Taken together, depending on their concentration, heparin-like glycosaminoglycans can either stimulate or antagonize the activity of cysteine protease B enzymes during parasite infection, suggesting that this glycoconjugate can anchor parasite cysteine protease at host cell surface.
authors.affiliation: Centro Interdisciplinar de Investigação Bioquímica, Universidade de Mogi das Cruzes, Mogi das Cruzes, Brazil.
authors.forename: Wagner A S
authors.initials: WA
authors.lastname: Judice
authors.forename: Marcella A
authors.initials: MA
authors.lastname: Manfredi
authors.forename: Gerson P
authors.initials: GP
authors.lastname: Souza
authors.forename: Thiago M
authors.initials: TM
authors.lastname: Sansevero
authors.forename: Paulo C
authors.initials: PC
authors.lastname: Almeida
authors.forename: Cláudio S
authors.initials: CS
authors.lastname: Shida
authors.forename: Tarsis F
authors.initials: TF
authors.lastname: Gesteira
authors.forename: Luiz
authors.initials: L
authors.lastname: Juliano
authors.forename: Gareth D
authors.initials: GD
authors.lastname: Westrop
authors.forename: Sanya J
authors.initials: SJ
authors.lastname: Sanderson
authors.forename: Graham H
authors.initials: GH
authors.lastname: Coombs
authors.forename: Ivarne L S
authors.initials: IL
authors.lastname: Tersariol
mesh_terms: D000818:Animals; D001483:Base Sequence; D056668:Cathepsin L / Q000235:genetics / Q000378:metabolism*; D002942:Circular Dichroism; D003001:Cloning, Molecular; D017931:DNA Primers; D006493:Heparin / Q000494:pharmacology*; D007700:Kinetics; D007894:Leishmania mexicana / Q000201:enzymology*; D016133:Polymerase Chain Reaction; D013050:Spectrometry, Fluorescence
chemical_list: D017931:DNA Primers; D006493:Heparin; D056668:Cathepsin L