TABLE 1.

Human and Mouse Transferrin (Swiss Prot accession# P02787 and Q921I1) Labeled with OP Agents

OP	Human-labeled peptide	Mouse-labeled peptide	OP-Tyr
FP-biotin	KPVDEY*K	KPVDQY*EDCYLAR	Y238
FP-biotin		LYLGHNY*VTAIR	Y319
FP-biotin		GY*YAVAVVK	Y429
FP-biotin		FDEFFSQGCAPGY*EK	Y491
FP-biotin		EEYNGY*TGAFR	Y518
FP-biotin	KPVEEY*ANCHLAR		Y574
DFP	KPVDEY*K	KPVDQY*EDCYLAR	Y238
DFP		GY*YAVAVVK	Y429
DFP	KPVEEY*ANCHLAR		Y574
CPO	KPVDEY*K	KPVDQY*EDCYLAR	Y238
CPO		LYLGHNY*VTAIR	Y319
CPO		GY*YAVAVVK	Y429
CPO		FDEFFSQGCAPGY*EK	Y491
CPO		EEYNGY*TGAFR	Y518
CPO	KPVEEY*ANCHLAR		Y574
Dichlorvos	KPVDEY*K		Y238
Dichlorvos	KPVEEY*ANCHLAR		Y574
Sarin	KPVDEY*K	KPVDQY*EDCYLAR	Y238
Sarin		GY*YAVAVVK	Y429
Sarin		GYY*AVAVVK	Y430
Sarin	KPVEEY*ANCHLAR		Y574
Soman	KPVDEY*K	KPVDQY*EDCYLAR	Y238
Soman		GYY*AVAVVK	Y430
Soman	KPVEEY*ANCHLAR		Y574

Note. Single letter codes for amino acids are A, ala; C, cys; D, asp; E, glu; F, phe; G, gly; H, his; I, ile, K, lys; L, leu; M, met; N, asn; P, pro; Q, gln; R, arg; S, ser; T, thr; V, val; W, trp; Y, tyr. The labeled tyrosine is designated by an asterisk Y*. The table shows the amino acid sequences of the tryptic peptides containing OP-labeled tyrosine. The location of the labeled tyrosine in the transferrin protein is given in the last column. Tyrosine 238 of transferrin was labeled in both species. Tyr 319, 429, 430, 491, and 518 was labeled only in mouse transferrin. Tyr 574 was labeled only in human transferrin. Transferrin 1 mg/ml in pH 8.5 buffer was treated in vitro with 0.5mM OP at 37°C for 16 h.