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Effect of detergents on in vitro 7α‐hydroxycholesterol formation by rat liver microsomes
Author(s) -
Sanghvi Ajit,
Grassi Enrico,
Bartman Candace,
Diven Warren F.
Publication year - 1982
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/bf02535372
Subject(s) - microsome , chemistry , chromatography , enzyme , in vitro , lipidology , clinical chemistry , yield (engineering) , mass spectrometry , microsoma , enzyme assay , biochemistry , kinetics , materials science , metallurgy , physics , quantum mechanics
Formation of 7α‐hydroxycholesterol by rat liver microsomes was quantitated using a gas chromatograph‐mass spectrometer (GC/MS) operated in selected ion monitoring (SIM) mode. Microsomes from normal rat livers incubated for different periods were found to yield increased 7α‐hydroxycholesterol with time. This was also true when incubations contained Tween‐80, but in this instance, the rate of 7α‐hydroxycholesterol production was lower and dependent on the concentration of Tween used. Similarly, Triton X‐100, Renex‐30, Kyro EOB, Cutscum, and Emulgen 911 all lowered the formation of 7α‐hydroxycholesterol by rat liver microsomes, whereas Triton WR‐1339 stimulated its production. Analysis of data obtained from following the enzyme reaction over an extended period using an integrated Michaelis‐Menten equation indicated the enzyme possesses a very significant affinity for the product (K s >K p ). Similar analysis shows that Tween‐80 is a noncompetitive inhibitor of the enzyme.