Table 2. Photochemical Oxidation of α₃Y and l-Tyrosine^a.

pH(D)	[α3Y] (μM)	kobs (s–1)	yield Y32–O•	kPCET (M–1 s–1)	KIE	[X] × kCOMP (s–1)	kY–O• (M–1 s–1)
pH 5.5	70	1.6 ± 0.1	0.58	(1.1 ± 0.2) × 104	2.5 ± 0.5	0.86 ± 0.04	(1.7 ± 0.7) × 104
	170	5.4 ± 0.1	0.55	(1.6 ± 0.2) × 104		2.7 ± 0.04
pD 5.5	410	4.9 ± 0.1	0.46	(5.4 ± 0.7) × 103		2.7 ± 0.05	–
	150	1.4 ± 0.1	0.58	(5.4 ± 0.9) × 103		0.79 ± 0.04
pH 8.5	580	210 ± 3	0.47	(1.7 ± 0.2) × 105	4.5 ± 0.9	110 ± 2	(1.1 ± 0.3) × 104
	890	420 ± 10	0.36	(1.9 ± 0.3) × 105		250 ± 6
pD 8.5	480	56 ± 1	0.28	(3.3 ± 0.5) × 104		40 ± 1	–
	940	130 ± 4	0.38	(4.8 ± 0.7) × 104		85 ± 2

	[Y] (μM)	kobs (s–1)	Yield Y–O•	kPCET (M–1 s–1)			kY–O• (M–1 s–1)
pH 5.5	260	420 ± 50	1.0	(2.5 ± 0.3) × 106		–	(1.9 ± 0.2) × 108
pH 8.5	260	(5.4 ± 0.1) × 104	1.0	(2.1 ± 0.2) × 108		–	(6.8 ± 0.9) × 108

^aRate constants and k^H/k^D KIEs are reported to one standard deviation.