title: Identification, purification, and characterization of a secretory serine protease in an Indian strain of Leishmania donovani.
abstract: An aprotinin sensitive serine protease was identified in the culture supernatant of the Indian strain of Leishmania donovani (MHOM/IN/1983/AG83). The protease was subsequently purified and characterized. The apparent molecular mass of the enzyme was 115 kDa in SDS-PAGE under non-reducing condition, while on reduction it showed a 56 kDa protein band indicating that the protease is a dimeric protein. The purified enzyme was optimally active at the pH and temperature of 7.5 and 28 degrees C, respectively. Assays of thermal stability indicated that the enzyme preserved 59% of activity even after pretreatment at 42 degrees C for 1 h. The purified protease was not glycosylated and its isoelectric pI was 5.0. N-alpha-p-tosyl-L-arginine methylester (TAME) appeared to be relatively better substrate among the commonly used synthetic substrates. The enzyme was inhibited by Ca(2+) and Mn(2+), but activated by Zn(2+). The protease could play important role(s) in the pathogenesis of visceral leishmaniasis or kala-azar.
authors.affiliation: Department of Biochemistry and Biophysics, University of Kalyani, Kalyani, West Bengal 741235, India.
authors.forename: Rajdeep
authors.initials: R
authors.lastname: Choudhury
authors.forename: Siddhartha Kumar
authors.initials: SK
authors.lastname: Bhaumik
authors.forename: Tripti
authors.initials: T
authors.lastname: De
authors.forename: Tapati
authors.initials: T
authors.lastname: Chakraborti
mesh_terms: D000818:Animals; D002413:Cations, Divalent / Q000737:chemistry / Q000378:metabolism; D004795:Enzyme Stability; D006031:Glycosylation; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007194:India; D007526:Isoelectric Point; D007893:Leishmania donovani / Q000201:enzymology*; D008670:Metals / Q000737:chemistry / Q000378:metabolism; D015800:Protozoan Proteins / Q000302:isolation & purification / Q000378:metabolism; D057057:Serine Proteases / Q000302:isolation & purification / Q000378:metabolism; D015842:Serine Proteinase Inhibitors / Q000378:metabolism; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D002413:Cations, Divalent; D008670:Metals; D015800:Protozoan Proteins; D015842:Serine Proteinase Inhibitors; D057057:Serine Proteases