Fmoc-D-Orn(Me)2-OH HCl

Protein acylation is a posttranslational modification in which an amino acid residue of a protein is acylated by a fatty acid. This process plays a key role in regulating proteomic function. Studies of protein acylation have relied on the development and application of extremely complicated molecular methods. However, global protein acylation can be profiled following hydrolysis of fatty acyl groups from cellular proteins. The present study aimed to develop a method for analysis of global protein acylation using gas-liquid chromatography (GLC). The total protein was extracted from the human hepatocellular carcinoma (HepG2) cell line. Protein sedimentation and extensive wash were combined with differential O-, S-, or N-acyl hydrolysis using sodium hydroxide (NaOH), hydroxylamine (NH2 OH), or hydrochloric acid (HCl), respectively. GLC with a flame ionization detector system was used to analyze changes in the fatty acid composition of the released lipids. The effect of selective inhibition of monounsaturated fatty acid (MUFA) synthesis on global protein acylation and the expression of reprogramming markers were determined to further validate the proposed profiling approach. In all hydrolysis conditions, the amount of myristate released was significantly higher than of other fatty acids. Notable differences were observed in the release of individual fatty acids among the hydrolyzing agents. Only NH2 OH could release significant amounts of palmitoleate (>2.5-fold vs. NaOH and HCl). The acylation assay indicates that treatment with a chemical inhibitor of monounsaturated fatty acid synthesis led to an overall increase in saturated fatty acid O- and N-acylation, and a decrease in palmitoleate O- and S-acylation of cellular proteins (<-15%). This was accompanied by significant reductions in the gene expression of the reprogramming markers Oct4 (-26%, P < 0.01) and Sox2 (-40%, P < 0.01). GLC-based analysis of global protein acylation affords a semi-quantitative method that can be used to assess the gross changes in the protein acylation profile during cell differentiation and reprogramming. © 2018 IUBMB Life, 71(3):340-346, 2019.

New mononuclear titanium and zirconium imido complexes [M(NR)(R'(2)calix)] [M=Ti, R'=Me, R=tBu (1), R=2,6-C(6)H(3)Me(2) (2), R=2,6-C(6)H(3)iPr(2) (3), R=2,4,6-C(6)H(2)Me(3) (4); M=Ti, R'=Bz, R=tBu (5), R=2,6-C(6)H(3)Me(2) (6), R=2,6-C(6)H(3)iPr(2) (7); M=Zr, R'=Me, R=2,6-C(6)H(3)iPr(2) (8)] supported by 1,3-diorganyl ether p-tert-butylcalix[4]arenes (R'(2)calix) were prepared in good yield from the readily available complexes [MCl(2)(Me(2)calix)], [Ti(NR)Cl(2)(py)(3)], and [Ti(NR)Cl(2)(NHMe(2))(2)]. The crystallographically characterised complex [Ti(NtBu)(Me(2)calix)] (1) reacts readily with CO(2), CS(2), and p-tolyl-isocyanate to give the isolated complexes [Ti[N(tBu)C(O)O](Me(2)calix)] (10), [[Ti(mu-O)(Me(2)calix)](2)] (11), [[Ti(mu-S)(Me(2)calix)](2)] (12), and [Ti[N(tBu)C(O)N(-4-C(6)H(4)Me)](Me(2)calix)] (13). In the case of CO(2) and CS(2), the addition of the heterocumulene to the Ti-N multiple bond is followed by a cycloreversion reaction to give the dinuclear complexes 11 and 12. The X-ray structure of 13.4(C(7)H(8)) clearly establishes the N,N'-coordination mode of the ureate ligand in this compound. Complex 1 undergoes tert-butyl/arylamine exchange reactions to form 2, 3, [Ti(N-4-C(6)H(4)Me)(Me(2)calix)] (14), [Ti(N-4-C(6)H(4)Fc)(Me(2)calix)] (15) [Fc=Fe(eta(5)-C(5)H(5))(eta(5)-C(5)H(4))], and [[Ti(Me(2)calix)](2)[mu-(N-4-C(6)H(4))(2)CH(2)]] (16). Reaction of 1 with H(2)O, H(2)S and HCl afforded the compounds [[Ti(mu-O)(Me(2)calix)](2)] (11), [[Ti(mu-S)(Me(2)calix)](2)] (12), and [TiCl(2)(Me(2)calix)] in excellent yields. Furthermore, treatment of 1 with two equivalents of phenols results in the formation of [Ti(O-4-C(6)H(4)R)(2)(Me(2)calix)] (R=Me 17 or tBu 18), [Ti(O-2,6-C(6)H(3)Me(2))(2)(Me(2)calix)] (19) and [Ti(mbmp)(Me(2)calix)] (20; H(2)mbmp=2,2'-methylene-bis(4-methyl-6-tert-butylphenol) or CH(2)([CH(3)][C(4)H(9)]C(6)H(2)-OH)(2)). The bis(phenolate) compounds 17 and 18 with para-substituted phenolate ligands undergo elimination and/or rearrangement reactions in the nonpolar solvents pentane or hexane. The metal-containing products of the elimination reactions are dinuclear complexes [[Ti(O-4-C(6)H(4)R)(Mecalix)](2)] [R=Me (23) or tBu (24)] where Mecalix=monomethyl ether of p-tert-butylcalix[4]arene. The products of the rearrangement reaction are [Ti(O-4-C(6)H(4)Me)(2) (paco-Me(2)calix)] (25) and [Ti(O-4-C(6)H(4)tBu)(2)(paco-Me(2)calix)] (26), in which the metallated calix[4]arene ligand is coordinated in a form reminiscent of the partial cone (paco) conformation of calix[4]arene. In these compounds, one of the methoxy groups is located inside the cavity of the calix[4]arene ligand. The complexes 24, 25 and 26 have been crystallographically characterised. Complexes with sterically more demanding phenolate ligands, namely 19 and 20 and the analogous zirconium complexes [Zr(O-4-C(6)H(4)Me)(2)(Me(2)calix)] (21) and [Zr(O-2,6-C(6)H(3)Me(2))(2)(Me(2)calix)] (22) do not rearrange. Density functional calculations for the model complexes [M(OC(6)H(5))(2)(Me(2)calix)] with the calixarene possessing either cone or partial cone conformations are briefly presented.

The reactivity of the cerium(IV) oxo complex [(LOEt)2CeIV(═O)(H2O)]·MeC(O)NH2 (1; LOEt- = [CoCp{P(O)(OEt)2}3]-, where Cp = η5-C5H5) toward electrophiles and Brønsted acids has been investigated. The treatment of 1 with acetic anhydride afforded the diacetate complex [CeIV(LOEt)2(O2CMe)2] (2). The reaction of 1 with B(C6F5)3 yielded [CeIV(LOEt)2(Me2CONH2)2][B(C6F5)3(OH)]2 (3), in which the [B(C6F5)3(OH)]- anions are H-bonded to the O-bound acetamide ligands. The treatment of 1 with HCl and HNO3 afforded [CeIV(LOEt)2Cl2] and [CeIV(LOEt)2(NO3)2], respectively. Protonation of 1 with triflic acid (HOTf) gave the diaqua complex [CeIV(LOEt)2(H2O)2](OTf)2 (4), in which the triflate anions are H-bonded to the two aqua ligands. The treatment of 1 with phenol afforded the phenoxide complex [CeIV(LOEt)2(OPh)2] (5). The oxo-bridged bimetallic complex [(LOEt)2(Me2CONH2)CeIV(O)NaLOEt] (6) with the Ce-Ooxo and Na-Ooxo distances of 1.953(4) and 2.341(4) Å, respectively, was obtained from the reaction of 1 with [NaLOEt]. Density functional theory calculations showed that the model complex [(LOMe)2CeIV(Me2CONH2)(O)NaLOMe] (6A; LOMe- = [CoCp{P(O)(OMe)2}3]-) contains a polarized Ce═O multiple bond. The energy for dissociation of the {NaLOMe} fragment from 6A in acetonitrile was calculated to be +33.7 kcal/mol, which is higher than that for dissociation of the H-bonded acetamide from [(LOMe)2CeIV(═O)(H2O)]·MeC(O)NH2 (1A) (calculated to be +17.4 kcal/mol). In hexanes containing trace water, complex 1 decomposed readily to a mixture of a tetranuclear cerium(IV) oxo cluster, [CeIV4(LOEt)4(μ4-O)(μ2-O)4(μ2-OH)2] (7), and a cerium(III) complex, [CeIII(LOEt)2(H2O)2][LOEt] [8(LOEt)], whereas the cerium/sodium oxo complex 6 is stable under the same conditions. The crystal structures of 3, 4·H2O, 6, and 8(LOEt) have been determined.