Reagents

1	L-Lysine: 2HCl (13C6) Catalog # CLM-2247 (Cambridge Isotope laboratories Inc, Andover MA.). 13C6 L-Lysine is a stable isotope of 12C6 L-Lysine and is 6 Da heavier than 12C6 L-Lysine.
2	L- Arginine:HCl (13C6) Catalog # CLM-2265 (Cambridge Isotope laboratories Inc, Andover MA.). 13C6 L- Arginine is a stable isotope of 12C6 L- Arginine and is 6 Da heavier than 12C6 L- Arginine.
3	L-Arginine:HCl (U-13C6, 15N4) Catalog # CNLM-539 (Cambridge Isotope laboratories Inc, Andover MA.). 13C6, 15N4 L- Arginine is a stable isotope of 12C6, 14N4 L- Arginine and is 10 Da heavier than 12C6 , 14N4 L- Arginine.
4	L-Arginine:HCl (U-13C6, 15N4, D7) Catalog # CDNLM-6801 (Cambridge Isotope laboratories Inc, Andover MA.).
5	L-Arginine:HCl (15N4, D7) Catalog # DNLM-7543 (Cambridge Isotope laboratories Inc, Andover MA.).
6	L-Lysine: 2HCl (13C6, 15N2) Catalog # CNLM-291 (Cambridge Isotope laboratories Inc, Andover MA.).
7	L-Lysine: 2HCl (13C6, 15N2, D9) Catalog # CDNLM-6810 (Cambridge Isotope laboratories Inc, Andover MA.).
8	L-Lysine: HCl (15N2, D9) Catalog # DNLM-7545 (Cambridge Isotope laboratories Inc, Andover MA.).
9	L-Lysine: 2HCl (4,4,5,5-D4) Catalog # DLM-2640 (Cambridge Isotope laboratories Inc, Andover MA.).
10	L-Methionine (1-13C, methyl-D3) Catalog # CDLM-760 (Cambridge Isotope laboratories Inc, Andover MA.).
11	L-Tyrosine ( 13C9; 9 Da) Catalog # CLM-2263 (Cambridge Isotope laboratories Inc, Andover MA.). 13C9 L- Tyrosine is a stable isotope of 12C9 L- Tyrosine and is 9 Da heavier than 12C9 L- Tyrosine.
12	- L-LYSINE*HCl (15N2) (Cat No#60,902-1, Sigma-Aldrich, Inc. St. Louis, MO). - L-LYSINE*HCl (13C6, 15N2) (Cat No#60,804-1, Sigma-Aldrich, Inc. St. Louis, MO). - L-ARGININE*HCl (15N4) (Cat No#60,011-3, Sigma-Aldrich, Inc. St. Louis, MO). - L-ARGININE*HCl (13C6, 15N4) (Cat No#60,803-3, Sigma-Aldrich, Inc. St. Louis, MO). - L-TYROSINE (15N) (Cat No#33,215-1, Sigma-Aldrich, Inc. St. Louis, MO). - L-TYROSINE (13C9, 15N) (Cat No#60,799-1, Sigma-Aldrich, Inc. St. Louis, MO).
13	DMEM and RPMI deficient in Lysine and Arginine: DMEM and RPMI 1640 deficient in above amino acids were custom synthesized from AthenaES, Baltimore, MD. http://www.athenaes.com.
14	Fetal Bovine Serum, Dialyzed (Catalog # 26400-044; Invitrogen, Carlsbad, CA).
15	Penicillin-Streptomycin (Catalog # 15140-122; Invitrogen, Carlsbad, CA).
16	Trypsin-EDTA (Catalog #25300-054; Invitrogen, Carlsbad, CA).
17	NP-40 (Catalog #492015; Calbiochem, EMD Biosciences, Inc. La Jolla, CA).
18	SDS (Catalog #L-5750; Sigma-Aldrich, St.Louis, MO).
19	Protease inhibitor tablets (Catalog #1697498  Roche Diagnostics).
20	Phosphate-buffered saline (Catalog #14190-144; Invitrogen, Carlsbad, CA).
21	Acetic acid, glacial (Catalog #A38-500; Fisher Chemicals, NJ).
22	Methanol (Catalog #MX0475P-4; EMD Chemicals Inc, NJ).
23	Sodium carbonate (Catalog #S-2127; Sigma-Aldrich, St.Louis, MO).
24	NH4HCO3 (Catalog #09830; Fluka, Sigma-Aldrich, St.Louis, MO).
25	Iodoacetamide (Catalog #I-6125; Sigma-Aldrich, St.Louis, MO).
26	Modified trypsin, sequencing grade (Catalog # V5111; Promega).
27	Colloidal Blue Staining Kit (Catalog # LC6025 Invitrogen, Carlsbad, CA).
28	Silver nitrate (Catalog # SX0205-5; EMD Chemicals Inc, NJ).
29	Sodium thiosulfate (Catalog # SX0820-1; EMD Chemicals Inc, NJ).