Conformational interpretation of intramolecular electron transfer in Met5-enkephalins between Tyr and Met(S:.Br) radical.
Mean distances between C beta atoms of redox centers and mean values of the exponentially distance dependent rate constants for intramolecular electron transfer, (k), in aqueous solution were calculated for Met5-enkephalin and its D-Ala2 analogue using the molecular mechanics and Monte Carlo techniques. The ratio of (k) values thus obtained proved similar to that determined experimentally for intramolecular electron transfer accompanying Met(S:.Br)----TyrO.radical transformation in these two peptides. This agreement indicates that the almost 2-fold difference observed between experimental k values for Met5-enkephalin and its D-Ala2 analogue can be attributed to the effect of Gly2 for D-Ala2 replacement on the average separation of the redox centers.
Vesterman
B
B
Institute of Organic Synthesis, Latvian Academy of Sciences, Riga, U.S.S.R.
Bobrowski
K
K
Betins
J
J
Nikiforovich
G V
GV
Wierzchowski
K L
KL
D004579:Electron Transport; D004744:Enkephalin, Methionine / Q000737:chemistry*; D005609:Free Radicals; D008715:Methionine / Q000737:chemistry*; D010084:Oxidation-Reduction; D011487:Protein Conformation; D014443:Tyrosine / Q000737:chemistry*
D005609:Free Radicals; D014443:Tyrosine; D004744:Enkephalin, Methionine; D008715:Methionine