Table 2.

Acid-catalyzed nitrosation/nitration of N-AcTyr

	AcATyr per 106 AcTyr
AcTyr	0.4 ± 0.1
+ HCl	2.0 ± 0.3†
+ HCl + NaNO2*	98.7 ± 10.0‡
+ HCl + NaNO3	10.3 ± 7.0§
+ HCl + NaNO3 + 1% phenol	3.8 ± 2.3§

AcTyr (1 mM) was incubated in 0.1 M NaOAc (pH 7.2) for 30 min on ice. Where indicated, 1 M HCl, sodium nitrite (10 μM), or sodium nitrate (10 μM), and/or 1% phenol were also included in the incubate. Samples were concentrated to dryness, reconstituted in 0.5 M KH₂PO₄ buffer (pH 7.0), reduced with DT, and analyzed as described. 

^*Control experiments indicated that N-acetyl-NTyr was the exclusive product of this nitrosation reaction. Values represent the mean ± SD of three determinations. 

^†P < 0.0005;  

^‡P < 0.0001;  

^§P < 0.05 compared to AcTyr control; one-tailed Students t test.