title: Physicochemical characterization of an aspin (rBm-33) from a filarial parasite Brugia malayi against the important human aspartic proteases.
abstract: The aspartic protease inhibitory efficiency of rBm-33, an aspin from a filarial parasite Brugia malayi was investigated. rBm-33 was found to be thermostable up to 90°C and it forms a stable 'enzyme-product' complex with human pepsin. Aspartic protease inhibitory activity was investigated using UV spectroscopy and isothermal titration calorimetry. Our results suggest that rBm-33 inhibits the activity of important human aspartic proteases that were examined with binding constants (Kb) values between 10.23 × 10(3) and 6.52 × 10(3) M(-1). The binding reactions were enthalpy driven with ΔHb values between -50.99 and -46.07 kJ mol(-1). From kinetic studies, pepsin inhibition by rBm-33 was found to be linear competitive with an inhibition constant (Ki) of 2.5 (±0.8) nM. Because of the inhibitory efficacy of Bm-33 against important human aspartic proteases which play a vital role in immune-regulation along with other functions, Bm-33 can be projected as a drug target for the filariasis.
authors.affiliation: University of Madras, CAS in Crystallography and Biophysics , Chennai , India.
authors.forename: Nagampalli Raghavendra Sashi
authors.initials: NR
authors.lastname: Krishna
authors.forename: N S A
authors.initials: NS
authors.lastname: Krushna
authors.forename: R B
authors.initials: RB
authors.lastname: Narayanan
authors.forename: S S
authors.initials: SS
authors.lastname: Rajan
authors.forename: K
authors.initials: K
authors.lastname: Gunasekaran
mesh_terms: D000818:Animals; D000947:Antigens, Helminth / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D057055:Aspartic Acid Proteases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D017178:Brugia malayi / Q000737:chemistry*; D002627:Chemistry, Physical; D004305:Dose-Response Relationship, Drug; D015801:Helminth Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D015394:Molecular Structure; D011480:Protease Inhibitors / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D055550:Protein Stability; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D013329:Structure-Activity Relationship; D013696:Temperature
chemical_list: D000947:Antigens, Helminth; C540446:Bm-33 protein, Brugia malayi; D015801:Helminth Proteins; D011480:Protease Inhibitors; D011994:Recombinant Proteins; D057055:Aspartic Acid Proteases