Dityrosine, 3,4-dihydroxyphenylalanine (DOPA), and radical formation from tyrosine residues on milk proteins with globular and flexible structures as a result of riboflavin-mediated photo-oxidation
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Dityrosine, 3,4-dihydroxyphenylalanine (DOPA), and radical formation from tyrosine residues on milk proteins with globular and flexible structures as a result of riboflavin-mediated photo-oxidation. / Dalsgaard, Trine K; Nielsen, Jacob H; Brown, Bronwyn E; Stadler, Nadina; Davies, Michael Jonathan.
In: Journal of Agricultural and Food Chemistry, Vol. 59, No. 14, 27.07.2011, p. 7939-47.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Dityrosine, 3,4-dihydroxyphenylalanine (DOPA), and radical formation from tyrosine residues on milk proteins with globular and flexible structures as a result of riboflavin-mediated photo-oxidation
AU - Dalsgaard, Trine K
AU - Nielsen, Jacob H
AU - Brown, Bronwyn E
AU - Stadler, Nadina
AU - Davies, Michael Jonathan
PY - 2011/7/27
Y1 - 2011/7/27
N2 - Riboflavin-mediated photo-oxidative damage to protein Tyr residues has been examined to determine whether protein structure influences competing protein oxidation pathways in single proteins and protein mixtures. EPR studies resulted in the detection of Tyr-derived o-semiquione radicals, with this species suggested to arise from oxidation of 3,4-dihydroxyphenylalanine (DOPA). The yield of this radical was lower in samples containing β-casein than in samples containing only globular proteins. Consistent with this observation, the yield of DOPA detected on β-casein was lower than that on two globular proteins, BSA and β-lactoglobulin. In contrast, samples with β-casein gave higher yields of dityrosine than samples containing BSA and β-lactoglobulin. These results indicate that the flexible structure of β-casein favors radical-radical termination of tyrosyl radicals to give dityrosine, whereas the less flexible structure of globular proteins decreases the propensity for tyrosyl radicals to dimerize, with this resulting in higher yields of DOPA and its secondary radical.
AB - Riboflavin-mediated photo-oxidative damage to protein Tyr residues has been examined to determine whether protein structure influences competing protein oxidation pathways in single proteins and protein mixtures. EPR studies resulted in the detection of Tyr-derived o-semiquione radicals, with this species suggested to arise from oxidation of 3,4-dihydroxyphenylalanine (DOPA). The yield of this radical was lower in samples containing β-casein than in samples containing only globular proteins. Consistent with this observation, the yield of DOPA detected on β-casein was lower than that on two globular proteins, BSA and β-lactoglobulin. In contrast, samples with β-casein gave higher yields of dityrosine than samples containing BSA and β-lactoglobulin. These results indicate that the flexible structure of β-casein favors radical-radical termination of tyrosyl radicals to give dityrosine, whereas the less flexible structure of globular proteins decreases the propensity for tyrosyl radicals to dimerize, with this resulting in higher yields of DOPA and its secondary radical.
KW - Amino Acid Motifs
KW - Animals
KW - Cattle
KW - Dihydroxyphenylalanine
KW - Free Radicals
KW - Lactoglobulins
KW - Milk Proteins
KW - Oxidation-Reduction
KW - Protein Conformation
KW - Riboflavin
KW - Serum Albumin, Bovine
KW - Tyrosine
U2 - 10.1021/jf200277r
DO - 10.1021/jf200277r
M3 - Journal article
C2 - 21696221
VL - 59
SP - 7939
EP - 7947
JO - Journal of Agricultural and Food Chemistry
JF - Journal of Agricultural and Food Chemistry
SN - 0021-8561
IS - 14
ER -
ID: 129669787