3 methyl l histidine

Histone proteins were purchased from the following commercial sources: unfractionated whole histone from calf thymus (Sigma-Aldrich; H9250) and histone H3 from calf thymus (Roche; 11034758001). Proteases qualified for use in mass spectrometry sample preparation are as follows: trypsin (Promega; V5111), chymotrypsin (Promega; V1061), and clostripain (Promega; V1881). Standards used in LC-MS/MS are as follows: L-lysine monohydrochloride (Sigma-Aldrich; L-5626), Nε-monomethyl-L-lysine hydrochloride (Sigma-Aldrich; 04,685), Nε,Nε -dimethyl-L-lysine monohydrochloride (Sigma-Aldrich; 19,773), Nε,Nε,Nε-trimethyl-lysine hydrochloride (Sigma-Aldrich; T1660), L-arginine hydrochloride (Arg, Sigma-Aldrich; A-5131), NG-monomethyl-L-arginine monoacetate salt (Sigma-Aldrich; 475,886), NG,NG-dimethylarginine dihydrochloride (Sigma-Aldrich; D4268), NG,N′G-dimethyl-L-arginine dihydrochloride (Santa Cruz; sc-222070), L-histidine hydrochloride monohydrate (His, Wako; 084–00702), 3-methyl-L-histidine (Sigma-Aldrich; M9005), 1-methyl-L-histidine (Sigma-Aldrich; 67,520), Nω-propyl-L-arginine hydrochloride (Wako; 512–27111).

For sample extraction and LC analysis we used Fisher Optima^TM grade solvents (Fisher Scientific, Hanover Park, IL). The chemical standards were purchased from Cayman Chemical Company (stachydrine hydrochloride [i.e., proline betaine]) (Ann Arbor, MI) or Sigma-Aldrich (debrisoquine, chlorpropamide, 4-nitrobenzoic acid, Nε,Nε,Nε-trimethyllysine hydrochloride [TML], L-carnitine, cis-aconitic acid, citric acid, N1-acetylspermidine dihydrochloride, N-acetyl-L-arginine, creatine, niacinamide, 3-methyl-L-histidine, betaine hydrochloride, L-pipecolic acid, indole-3-acetic acid, and indoxyl sulfate) (St. Louis, MO). The hexosamine-valine-isoleucine-OH (Hex-V-I) was synthesized by Expert Synthesis Solutions (London, ON, Canada) with details previously provided [27 (link)]. Quality control reference materials were obtained from the National Institute of Standards and Technology (NIST) (NIST Standard Reference Material 3667 [creatinine in frozen human urine] and NIST Standard Reference Material 1950 [metabolites in frozen human plasma]).