TABLE 2

Summary of mass spectral data of radioactive [¹⁴C]HKI-272 peptide adducts obtained by HCl hydrolysis of human plasma incubated with [¹⁴C]HKI-272 for 6 h

HKI-272 Adducts	Matching Residue	Precursor MH⁺	Product Ions
K^*	190^**	703.311	557, 658, 488, 147(d)
GK^*	189–190^**	760.333	557, 315(a), 273(b), 228(c), 204(d)
K^*A	190–191^**	774.349	557, 329(a), 287(b), 242(c), 218(d)
GK^*A	189–191	831.370	557, 386(a), 344(b), 299(c), 275(d)
K^*AS	190–192	861.382	557, 416(a), 374(b), 329(c), 305(d)
GK^*AS	189–192	918.403	557, 473(a), 431(b), 386(c), 362(d)
EGK^*A	188–191	960.413	557, 515(a), 473(b), 428(c), 404(d)

↵* , the AA residue to which HKI-272 is bound;
↵** , more than one matching; (), fragmentation pathway of product ion formation (see Fig. 1).