Metabolism of some ω-halogenoalkylbenzenes and related alcohols in the rabbit

Ca2+ or Mg2+ (1-67 mm). These did not inhibit lysolecithin hydrolysis by the enzyme preparation. 6. Fluoride completely inhibited promoted lecithinase activity and lysolecithin hydrolysis at 4-1 mm and inhibition was still apparent at 0-41 mM. 7. Splitting of the acyl fatty-ester bonds in the activating lipids cardiolipin or monophosphoinositide by mild alkaline hydrolysis resulted in a complete loss of the ability to promote lecithin hydrolysis. 8. Monophosphoinositide (but not cardiolipin or tripalmitin) was hydrolysed by the enzyme preparation and this attack was inhibited by lecithin. 9. No transfer of fatty acids from lecithin labelled with 14C-fatty acid to monophosphoinositide could be demonstrated in the presence of the enzyme preparation. 10. The activating lipids caused no detectable precipitation of phospholipase B on the surface of the lecithin particles, as measured by the lysolecithinase activity of the particles and supernatant. 11. Small quantities of cardiolipin and monophosphoinositide completely changed the surface character of lecithin particles in aqueous emulsion, so that the lecithin became no longer extractable into organic solvents such as ether. 12. The promotion of lecithinase activity by cardiolipin or monophosphoinositide occurred at a concentration at which the surface of the lecithin particle had changed so that it had become substantially non-extractable into ether. Both the surface change and the enzymic activity could be prevented by the addition of Ca2+ ions. 13. It is suggested that cardiolipin and monophosphoinositide promote lecithin hydrolysis by P. notatum phospholipase B preparations by introducing on the surface of the lecithin particles, certain polar groups which are necessary for the enzymic attack. I wish to thank Sir Rudolph Peters, F.R.S., for the interest he has displayed in this investigation, and also Miss Norma Hemington and Mr R. W. White for much valuable assistance. The Distillers Co. Ltd. are thanked for a supply of corn-steep liquor.