Influences of apolipoprotein E on soluble and heparin-immobilized hepatic lipase
Journal Article
·
· Am. J. Physiol.; (United States)
OSTI ID:7039889
The effect of human apolipoprotein E (apoE), either alone or in combination with apoC, on the lipolysis of a radiolabeled triglyceride emulsion was studied with hepatic lipase in solution and immobilized on heparin-Sepharose. The soluble hepatic lipase was inhibited, whereas the heparin-immobilized lipase was stimulated by apoE. This stimulation was attenuated by combining apoE with either apoC-II or C-III. The heparin-immobilized lipase demonstrated much less lipolysis of the zwitterionic phosphatidylcholine-stabilized triglyceride emulsion than did the soluble enzyme. This difference was less when the emulsion was stabilized by a nonionic detergent. apoE inhibited lipase activity when assayed under conditions (0.4 M NaCl) of bound enzyme and unbound substrate. Increasing the emulsion apoE content beyond optimum inhibited lipolysis by the immobilized enzyme. Kinetic analysis of phosphatidylcholine-stabilized triglyceride emulsions revealed a significant decrease in immobilized enzyme K/sub m/ and an increase in V/sub max/ when the emulsion was supplemented with apoE. Distributing the immobilized lipase in clustered aggregates produced more lipolysis than when the same enzyme content was uniformly bound.
- Research Organization:
- Duke Univ. Medical Center, Durham, NC (USA)
- OSTI ID:
- 7039889
- Journal Information:
- Am. J. Physiol.; (United States), Journal Name: Am. J. Physiol.; (United States) Vol. 252:6; ISSN AJPHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
APOLIPOPROTEINS
BIOCHEMICAL REACTION KINETICS
BIOCHEMISTRY
BODY
CARBON 14 COMPOUNDS
CARBOXYLESTERASES
CHEMISTRY
COLLOIDS
DIGESTIVE SYSTEM
DISPERSIONS
DOSE-RESPONSE RELATIONSHIPS
ELECTROPHORESIS
EMULSIONS
ENZYME ACTIVITY
ENZYMES
ESTERASES
ESTERS
GLANDS
HYDROLASES
KINETICS
LABELLED COMPOUNDS
LIPASE
LIPIDS
LIPOPROTEINS
LIVER
LYSIS
ORGANIC COMPOUNDS
ORGANS
PROTEINS
PURIFICATION
REACTION KINETICS
TRIGLYCERIDES
TRITIUM COMPOUNDS
59 BASIC BIOLOGICAL SCIENCES
APOLIPOPROTEINS
BIOCHEMICAL REACTION KINETICS
BIOCHEMISTRY
BODY
CARBON 14 COMPOUNDS
CARBOXYLESTERASES
CHEMISTRY
COLLOIDS
DIGESTIVE SYSTEM
DISPERSIONS
DOSE-RESPONSE RELATIONSHIPS
ELECTROPHORESIS
EMULSIONS
ENZYME ACTIVITY
ENZYMES
ESTERASES
ESTERS
GLANDS
HYDROLASES
KINETICS
LABELLED COMPOUNDS
LIPASE
LIPIDS
LIPOPROTEINS
LIVER
LYSIS
ORGANIC COMPOUNDS
ORGANS
PROTEINS
PURIFICATION
REACTION KINETICS
TRIGLYCERIDES
TRITIUM COMPOUNDS