Table 1.

Characteristic absorption properties of bacteriorhodopsin mutants before and after spin labeling

	Abs. max. (nm) before spin labeling	Abs. max. (nm) after spin labeling	Intermediates and occupancies, pH 6	Intermediates and occupancies, pH 9
V49A	565 nm	N/A	N′ (22%)	N (21%)
A103R1/M163R1	565 nm	564 nm	N′ (28%)	N (26%);M (2%)
V101R1/A168R1	565 nm	563 nm	N′ (20%)	N (25%);M (2%)
L100R1/T170R1	564 nm	563 nm	N′ (19%)	N (22%)
S169R1/S226R1	565 nm	564 nm	N′ (22%)	N (20%)
G106R1/G155R1	564 nm	562 nm	N′ (23%);L (6%)	N (15%);M (9%)

All mutants contained the V49A residue change as background. The occupancies of N, N′, L, or M intermediates are shown for the spin-labeled mutants under continuous illumination with 635 nm light.