SINGLET MOLECULAR OXYGEN QUENCHING BY SATURATED AND UNSATURATED FATTY-ACIDS AND BY CHOLESTEROL |
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| Authors: | C Vever-Bizet M Dellinger D Brault M Rougee R V Bensasson |
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| Institution: | Laboratoire de Biophysique, INSERM U. 201, CNRS UA 481, Museum National D'Histoire Naturelle, 43 rue Cuvier, 75231 Paris Cedex 05, France |
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| Abstract: | The rate constants of molecular singlet oxygen quenching by saturated and unsaturated fatty-acids and by cholesterol-membrane critical components - membrane critical components - have been measured by time resolved detection of the 1270 nm phosphorescence of singlet molecular oxygen O2(1deltag)]. We have determined (i) an increment of 5.7 x 10(2)M(-1)s(-1) per -CH2- in C6D6 and CD3OD for saturated fatty acids between C4 and C20, (ii) an increment of 3 x 10(4)M(-1)s(-1) per non-conjugated cis-double bond for C18 unsaturated fatty acids, identical in C6D6 and DC3OD, (iii) a lower quenching rate constant by a factor of 2.7 for the trans-C16 and trans-C18 as compared to the corresponding cis-monounsaturated fatty acids, (iv) a rate constant of O2x(1deltag) quenching by cholesterol of 5.7 x 10(4)M(-1)s(-1) in benzene. These rate constants are compared to those obtained for other membrane cellular components. |
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