Steiner R F, Motevalli-Alibadi M
Arch Biochem Biophys. 1984 Nov 1;234(2):522-30. doi: 10.1016/0003-9861(84)90299-6.
The average separation of the phenolic groups of tyrosine-99 and tyrosine-138 has been measured by radiationless energy transfer between each tyrosine and the nitro derivative of the second tyrosine. A separation of 16.7 +/- 0.7 A was found in the absence of Ca2+ and 15.5 +/- 0.7 A in the presence of Ca2+.