Mechanism of inhibition of rat brain adenosine triphosphatase by mercuric chloride
- Selma Univ., AL (USA)
Mercuric Chloride (Hg), a neurotoxic compound inhibited ATPase system of rat brain microsomes. Membrane bound enzymes, Na{sup +}-K{sup +} ATPase (IC{sub 50} = 2.35 {times} 10{sup {minus}7M}) and K-paranitrophenyl phosphatase (K-PNPPase) (IC{sub 50} = 2.7 {times} 10{sup {minus}7M}) and {sup 3}H-Ouabain binding (IC{sub 50} = 3.3 {times} 10{sup {minus}7M}) were inhibited by Hg at micromolar concentrations in a dose dependent manner. Hydrolysis of ATP was linear with time with or without Hg in the reaction mixtures. Altered pH or temperature versus enzyme activity showed higher inhibition by Hg at basic pH (8.0-9.0) and at lower temperatures (17-32{degree}C). Activation energy ({Delta}E) values were increased at 27-37{degree}C in the presence of Hg. Kinetic studies of cationic-substrate activation of Na{sup +}-K{sup +} ATPase and K-PNPPase in the presence of Hg showed significant changes in kinetic constant (K{sub m} and V{sub max}). Inhibition of Na{sup +}-K{sup +} ATPase was partially restored by repeated washings of microsomes. Preincubation with sulfhydryl agents protected Na{sup +}-K{sup +} ATPase from Hg inhibition. Cumulative inhibition studies with Hg and ouabain indicated possible interaction between the two inhibitors of Na{sup +}-K{sup +} ATPase by interacting at Na{sup +} and K{sup +} sites.
- OSTI ID:
- 6831869
- Journal Information:
- FASEB Journal (Federation of American Societies for Experimental Biology); (USA), Vol. 3:3; ISSN 0892-6638
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
ATP-ASE
BIOCHEMICAL REACTION KINETICS
MERCURY CHLORIDES
TOXICITY
ATP
BIOLOGICAL EFFECTS
BRAIN
DOSE-RESPONSE RELATIONSHIPS
ENZYME ACTIVITY
INHIBITION
MICROSOMES
PH VALUE
RATS
TEMPERATURE EFFECTS
THIOLS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
ACID ANHYDRASES
ANIMALS
BODY
CELL CONSTITUENTS
CENTRAL NERVOUS SYSTEM
CHLORIDES
CHLORINE COMPOUNDS
ENZYMES
HALIDES
HALOGEN COMPOUNDS
HYDROGEN COMPOUNDS
HYDROLASES
ISOTOPE APPLICATIONS
KINETICS
MAMMALS
MERCURY COMPOUNDS
MERCURY HALIDES
NERVOUS SYSTEM
NUCLEOTIDES
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
ORGANOIDS
ORGANS
PHOSPHOHYDROLASES
REACTION KINETICS
RIBOSOMES
RODENTS
VERTEBRATES
560300* - Chemicals Metabolism & Toxicology
550201 - Biochemistry- Tracer Techniques