Reactivity of sarcoplasmic reticulum from rabbit cardiac muscle with 1-fluoro- and 1,5-difluoro- 2,4-dinitrobenzene.
Sarcoplasmic reticulum preparations from rabbit cardiac and fast skeletal muscle react differentially with low concentrations of 1-fluoro- and 1,5-difluoro-2,4-dinitrobenzene. Dinitrophenylation of cardiac sarcoplasmic reticulum by 1-fluoro-2,4-dinitrobenzene is not affected by Ca2+ and is limited to the lipoprotein-lipid region. This contrasts sharply with the predominant Ca2+-dependent dinitrophenylation of the ATPase protein of rabbit skeletal sarcoplasmic reticulum by this reagent. Formation of non-serial high mol. wt. oligomers by 1,5-difluoro-2,4-dinitrobenzene is significantly greater in cardiac than in skeletal vesicles. Substrate MgATP2- does not protect rabbit cardiac sarcoplasmic reticulum ATPase activity or Ca2+ uptake from dinitrophenylation when monofunctional and bifunctional reagents are used. Chemical differences in the overall structure of the two kinds of membrane preparations can be ascertained from a comparison of the effects of Ca2+ and MgATP2- on the reactivity of these reagents.
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000378:metabolism; D004139:Dinitrofluorobenzene / Q000494:pharmacology*; D006321:Heart / Q000187:drug effects*; D009124:Muscle Proteins / Q000378:metabolism; D009132:Muscles / Q000378:metabolism; D009578:Nitrobenzenes / Q000494:pharmacology*; D011506:Proteins / Q000378:metabolism; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000187:drug effects*
D009124:Muscle Proteins; D009578:Nitrobenzenes; D011506:Proteins; D000255:Adenosine Triphosphate; D004139:Dinitrofluorobenzene; D000252:Calcium-Transporting ATPases; D002118:Calcium