Pulmonary surfactant synthesis. A highly active microsomal phosphatidate phosphohydrolase in the lung

Journal Article · Mon May 01 04:00:00 EDT 1978 · J. Lipid Res.; (United States)

OSTI ID:5616910

Mavis, R D; Finkelstein, J N; Hall, B P

Lung cell-free homogenate, which contains about twice the units of phosphatidate phosphohydrolase per mg of protein compared to liver, was fractionated by differential centrifugation and the fractions were assayed for phosphatidate phosphohydrolase and marker enzymes of endoplasmic reticulum, mitochondria, and lysosomes. Over 60% of the lung phosphatidate phosphohydrolase was associated with the endoplasmic reticulum, compared to 50% of the total liver enzyme. Thus a major portion of the more active lung enzyme is potentially involved in lipid biosynthesis by the endoplasmic reticulum. Less than 0.2% of the total lung enzyme was found in a lamellar body fraction, consistent with previous findings. The lung microsomal phosphohydrolase was specific for lipid substrates, showing equal activity towards phosphatidic acid or lysophosphatidic acid and relatively low activities towards glycerophosphates. It had a neutral pH optimum, similar to the liver enzyme, but differed somewhat in its relative activity at extremes of pH. Stability at 65/sup 0/C was greater for the lung enzyme. Fluoride inhibited lung (or liver) microsomal phosphatidate phosphohydrolase, while tartrate, MgCl/sub 2/, or EDTA had no effect. The presence of a high activity of phosphatidate phosphohydrolase in lung endoplasmic reticulum is consistent with the rapid synthesis of pulmonary surfactant phosphatidylcholine.

• Research Organization: Univ. of Rochester, NY
• OSTI ID: 5616910
• Journal Information: J. Lipid Res.; (United States), Journal Name: J. Lipid Res.; (United States) Vol. 19:4; ISSN JLPRA
• Country of Publication: United States
• Language: English

Related Subjects

550200* -- Biochemistry
550500 -- Metabolism
59 BASIC BIOLOGICAL SCIENCES
ALKALINE EARTH METAL COMPOUNDS
AMINO ACIDS
BIOSYNTHESIS
BODY
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CENTRIFUGATION
CHELATING AGENTS
CHLORIDES
CHLORINE COMPOUNDS
EDTA
ELEMENTS
ENDOPLASMIC RETICULUM
ENZYMES
FLUORIDES
FLUORINE
FLUORINE COMPOUNDS
HALIDES
HALOGEN COMPOUNDS
HALOGENS
LIPIDS
LUNGS
LYSOSOMES
MAGNESIUM CHLORIDES
MAGNESIUM COMPOUNDS
MITOCHONDRIA
NONMETALS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANOIDS
ORGANS
RESPIRATORY SYSTEM
SEPARATION PROCESSES
SURFACTANTS
SYNTHESIS