A high affinity Ca2(+)-ATPase on the surface membrane of Leishmania donovani promastigote

Journal Article · Thu Jul 05 04:00:00 EDT 1990 · Journal of Biological Chemistry; (USA)

OSTI ID:6650762

Ghosh, J; Ray, M; Sarkar, S; Bhaduri, A ^[1]

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1. Indian Institute of Chemical Biology, Calcutta (India)

A Ca2(+)-dependent ATP-hydrolytic activity was detected in the crude membrane ghost of the promastigote or vector form of the protozoal parasite Leishmania donovani, the pathogen responsible for kala azar. The Ca2(+)-ATPase was purified to apparent homogeneity after solubilization with deoxycholate. The enzyme consists of two subunits of Mr = 51,000 and 57,000 and has an apparent molecular weight of 215,000 +/- 12,000. The enzyme activity is exclusively dependent on Ca2+, and the pure enzyme can hydrolyze 1.6 mumol of ATP/min/mg of protein. The apparent Km for Ca2+ is 35 nM, which is further reduced to 12 nM in the presence of heterologous calmodulin. The enzyme is sensitive to vanadate, but is insensitive to oligomycin and ouabain. The enzyme is strongly associated with the plasma membrane and has its catalytic site oriented toward the cytoplasmic face. The enzyme spans across the plasma membrane as surface labeling with radioiodine shows considerable radioactivity in the completely purified enzyme. The localization and orientation of this high affinity, calmodulin-sensitive Ca2(+)-ATPase suggest some role of this enzyme in Ca2+ movement in the life cycle of this protozoal parasite.

• OSTI ID: 6650762
• Journal Information: Journal of Biological Chemistry; (USA), Journal Name: Journal of Biological Chemistry; (USA) Vol. 265:19; ISSN JBCHA; ISSN 0021-9258
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ACID ANHYDRASES
ALKALINE EARTH METAL COMPOUNDS
ANIMALS
ATP-ASE
BIOLOGICAL LOCALIZATION
CALCIUM COMPOUNDS
CALMODULIN
CARBOHYDRATES
CARDIAC GLYCOSIDES
CARDIOTONICS
CARDIOVASCULAR AGENTS
CATALYSIS
CELL CONSTITUENTS
CELL MEMBRANES
CYTOPLASM
DRUGS
ENZYME ACTIVITY
ENZYMES
GLYCOSIDES
HYDROLASES
INVERTEBRATES
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
LIFE CYCLE
MEMBRANES
MICROORGANISMS
MOLECULAR WEIGHT
ORGANIC COMPOUNDS
OUABAIN
OXYGEN COMPOUNDS
PARASITES
PHOSPHOHYDROLASES
PROTEINS
PROTOZOA
STROPHANTHINS
TRACER TECHNIQUES
TRANSITION ELEMENT COMPOUNDS
VANADATES
VANADIUM COMPOUNDS