1. Orthovanadate-Induced Vasoconstriction of Rat Mesenteric Arteries Is Mediated by Rho Kinase-Dependent Inhibition of Myosin Light Chain Phosphatase
Kazuya Ito, Mai Matsuzaki, Tomoya Sasahara, Mariko Shin, Katsutoshi Yayama Biol Pharm Bull. 2015;38(11):1809-16. doi: 10.1248/bpb.b15-00587.
Orthovanadate (OVA), a protein tyrosine phosphatase inhibitor, induces vasoconstriction in a Rho kinase-dependent manner. The aim of this study was to determine the mechanism underlying OVA-induced vasoconstriction of rat mesenteric arteries. OVA-induced constriction of mesenteric arterial rings treated with N(G)-nitro-L-arginine methyl ester (L-NAME, 0.1 mM), a nitric oxide synthase inhibitor, was significantly blocked by the Rho kinase inhibitor Y-27632 (R-(+)-trans-N-(4-pyridyl)-4-(1-aminoethyl)-cyclohexanecarboxamide, 10 µM), extracellular signal-regulated kinase 1 and 2 (Erk1/2) inhibitor FR180204 (5-(2-phenyl-pyrazolo[1,5-a]pyridin-3-yl)-1H-pyrazolo[3,4-c]pyridazin-3-ylamine, 10 µM), Erk1/2 kinase (MEK) inhibitor PD98059 (2'-amino-3'-methoxyflavone, 10 µM), epidermal growth factor receptor (EGFR) inhibitor AG1478 (4-(3-chloroanilino)-6,7-dimethoxyquinazoline, 10 µM), and Src inhibitor PP2 (4-amino-3-(4-chlorophenyl)-1-(t-butyl)-1H-pyrazolo[3,4-d]pyrimidine, 3 µM). However, the myosin light chain kinase inhibitor ML-7 (1-(5-iodonaphthalene-1-sulfonyl)-homopiperazine, 10 µM) did not affect OVA-induced constriction. Phosphorylation of myosin phosphatase target subunit 1 (MYPT1, an index of Rho kinase activity) was abrogated by inhibitors of Src, EGFR MEK, Erk1/2, and Rho kinase. OVA-stimulated Erk1/2 phosphorylation was blocked by inhibitors of EGFR, Src, MEK, and Erk1/2 but not affected by an inhibitor of Rho kinase. OVA-induced Src phosphorylation was abrogated by an Src inhibitor but not affected by inhibitors of EGFR, MEK, Erk1/2, and Rho kinase. In addition, the metalloproteinase inhibitor TAPI-0 (N-(R)-[2-(hydroxyaminocarbonyl)methyl]-4-methylpentanoyl-L-naphthylalanyl-L-alanine amide, 10 µM) and an inhibitor of heparin/epidermal growth factor binding (CRM 197, 10 µg/mL) did not affect OVA-induced contraction of rat mesenteric arterial rings. These results suggest that OVA induces vasoconstriction in rat mesenteric arteries via Src, EGFR, MEK, and Erk1/2 activation, leading to the inactivation of myosin light chain phosphatase through phosphorylation of MYPT1.
2. Imatinibium dipicrate
Jerry P Jasinski, Ray J Butcher, Q N M Hakim Al-Arique, H S Yathirajan, B Narayana Acta Crystallogr Sect E Struct Rep Online. 2010 Jan 20;66(Pt 2):o411-2. doi: 10.1107/S1600536810000577.
IN THE CRYSTAL STRUCTURE OF IMATINIBIUM DIPICRATE [SYSTEMATIC NAME: 1-methyl-4-(4-{4-methyl-3-[4-(3-pyrid-yl)pyrimidin-2-yl-amino]-anilinocarbon-yl}benz-yl)piperazine-1,4-diium dipicrate], C(29)H(33)N(7)O(2+)·2C(6)H(2)N(3)O(7) (-), the imatinibium cation is proton-ated at both of the pyrimidine N atoms. Each of the two picrate anions inter-acts with the diprotonated cation through bifurcated N-H⋯O hydrogen bonds forming R(1) (2)(6) ring motifs. Also, an R(2) (2)(24) graph set is formed between the benzamidium -NH- group and the 4-pyridyl N atom inter-acting through N-H⋯N hydrogen-bond inter-actions. Additional weak C-H⋯Cg π-ring and π-π inter-molecular inter-actions are observed which also influence crystal packing.
3. Piperazines for peptide carboxyl group derivatization: effect of derivatization reagents and properties of peptides on signal enhancement in matrix-assisted laser desorption/ionization mass spectrometry
Xiaoqiang Qiao, Liangliang Sun, Lingfan Chen, Yuan Zhou, Kaiguang Yang, Zhen Liang, Lihua Zhang, Yukui Zhang Rapid Commun Mass Spectrom. 2011 Mar 15;25(5):639-46. doi: 10.1002/rcm.4903.
Piperazine-based derivatives, including 1-(2-pyridyl)piperazine (2-PP), 1-(2-pyrimidyl)piperazine (2-PMP), 1-(4-pyridyl)piperazine (4-PP), and 1-(1-methyl-4-piperidinyl)piperazine (M-PP), were used for the derivatization of carboxyl groups on peptides with 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) and 1-hydroxy-7-azabenzotriazole (HOAt) as coupling reagents, and trifluoroacetic acid (TFA) as activator. Taking synthetic peptides RVYVHPI (RI-7) and APGDRIYVHPF (AF-11) as samples, the yields of derivatized peptides by 2-PP, 2-PMP and 4-PP were higher than 94%. The effect of piperazine derivatives on the signals of tryptic digests of α-transferrin and bovine serum albumin (BSA) was investigated, and it was found that peptides derivatized by 2-PP and 2-PMP exhibited obviously improved ionization efficiency. Furthermore, comparison of identified peptides before and after derivatization showed that peptides with low molecular weight (MW) and high pI value were preferably detected after derivatization. In addition, after derivatization with 2-PP and 2-PMP, protein myelin basic protein S, 20 kDa protein, and histone H were confidently identified from the tryptic digests of two fractions of rat brain protein separated by reversed-phase high-performance liquid chromatography (HPLC), indicating the potential application of 2-PP and 2-PMP for the highly sensitive determination of peptides in comprehensive proteome analysis.
