Singlet molecular oxygen quenching by saturated and unsaturated fatty-acids and by cholesterol.
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.
C
C
Vever-Bizet
M
M
Dellinger
D
D
Brault
M
M
Rougee
R V
RV
Bensasson
D002784:Cholesterol; D005227:Fatty Acids; D005231:Fatty Acids, Unsaturated; D010100:Oxygen; D010777:Photochemistry; D013329:Structure-Activity Relationship
D005227:Fatty Acids; D005231:Fatty Acids, Unsaturated; D002784:Cholesterol; D010100:Oxygen