2
|
Rush MD, van Breemen RB. Role of ammonium in the ionization of phosphatidylcholines during electrospray mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2017; 31:264-268. [PMID: 27862466 PMCID: PMC5253255 DOI: 10.1002/rcm.7788] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Revised: 11/04/2016] [Accepted: 11/05/2016] [Indexed: 05/09/2023]
Abstract
RATIONALE Electrospray mass spectrometry methods for the analysis of phosphatidylcholines (PCs) routinely include ammonium acetate or ammonium formate in the mobile phase. In an effort to justify and optimize the use of these additives, we investigated possible functions of ammonium compounds in the ionization of PCs. METHODS Because PCs contain a quaternary amine, the role of ammonium in neutralizing the negatively charged phosphate group was investigated by using deuterated ammonium acetate, adjusting the pH, varying the organic solvent composition, and by comparing the additives ammonium acetate, ammonium formate and ammonium bicarbonate. Seven PC standards were measured ranging from lyso 1-palmitoyl-sn-glycero-3-phosphocholine to 1,2-dieicosapentaenoyl-sn-glycero-3-phosphocholine as well as a mixture of PCs in a krill oil dietary supplement. RESULTS Under all conditions tested, aqueous acetonitrile provided more abundant formation of protonated PCs than did aqueous methanol. Regardless of the mobile phase composition and electrospray ion source parameters, no [M + NH4 ]+ ions were detected. Adding deuterated ammonium acetate to the mobile phase failed to form deuterated PCs, indicating that ammonium is not the source of the proton that neutralizes the phosphate negative charge. Instead, water was the source of the proton as deuterated water resulted in the formation of [M + D]+ ions. Addition of organic acids, ammonium formate, ammonium acetate, or ammonium bicarbonate to the mobile phase did not enhance and in most cases suppressed PC ionization. CONCLUSIONS Ammonium compounds and organic acids can suppress ionization of PCs when using an aqueous acetonitrile mobile phase during electrospray. Copyright © 2016 John Wiley & Sons, Ltd.
Collapse
Affiliation(s)
- Michael D Rush
- Chicago Mass Spectrometry Laboratory, Department of Medicinal Chemistry and Pharmacognosy, University of Illinois College of Pharmacy, 833 South Wood St., Chicago, IL, 60612, USA
| | - Richard B van Breemen
- Chicago Mass Spectrometry Laboratory, Department of Medicinal Chemistry and Pharmacognosy, University of Illinois College of Pharmacy, 833 South Wood St., Chicago, IL, 60612, USA
| |
Collapse
|
3
|
Tang DQ, Zou L, Yin XX, Ong CN. HILIC-MS for metabolomics: An attractive and complementary approach to RPLC-MS. MASS SPECTROMETRY REVIEWS 2016; 35:574-600. [PMID: 25284160 DOI: 10.1002/mas.21445] [Citation(s) in RCA: 121] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Accepted: 07/28/2014] [Indexed: 05/14/2023]
Abstract
Hydrophilic interaction chromatography (HILIC) is an emerging separation mode of liquid chromatography (LC). Using highly hydrophilic stationary phases capable of retaining polar/ionic metabolites, and accompany with high organic content mobile phase that offer readily compatibility with mass spectrometry (MS) has made HILIC an attractive complementary tool to the widely used reverse-phase (RP) chromatographic separations in metabolomic studies. The combination of HILIC and RPLC coupled with an MS detector expands the number of detected analytes and provides more comprehensive metabolite coverage than use of only RP chromatography. This review describes the recent applications of HILIC-MS/MS in metabolomic studies, ranging from amino acids, lipids, nucleotides, organic acids, pharmaceuticals, and metabolites of specific nature. The biological systems investigated include microbials, cultured cell line, plants, herbal medicine, urine, and serum as well as tissues from animals and humans. Owing to its unique capability to measure more-polar biomolecules, the HILIC separation technique would no doubt enhance the comprehensiveness of metabolite detection, and add significant value for metabolomic investigations. © 2014 Wiley Periodicals, Inc. Mass Spec Rev 35:574-600, 2016.
Collapse
Affiliation(s)
- Dao-Quan Tang
- Department of Pharmaceutical Analysis, Xuzhou Medical College, Xuzhou, 221044, China
- Jiangsu Key Lab for the study of New Drug and Clinical Pharmacy, Xuzhou Medical College, Yunlong, China
- NUS Environmental Research Inst., National University of Singapore, 5 A Engineering Srive 1, Singapore, 117411, Singapore
| | - Ll Zou
- Saw Swee Hock School of Public Health, National University of Singapore, 16 Medical Drive, Singapore, 117597, Singapore
| | - Xiao-Xing Yin
- Jiangsu Key Lab for the study of New Drug and Clinical Pharmacy, Xuzhou Medical College, Yunlong, China
| | - Choon Nam Ong
- NUS Environmental Research Inst., National University of Singapore, 5 A Engineering Srive 1, Singapore, 117411, Singapore
- Saw Swee Hock School of Public Health, National University of Singapore, 16 Medical Drive, Singapore, 117597, Singapore
| |
Collapse
|
4
|
Morita J, Kano K, Kato K, Takita H, Sakagami H, Yamamoto Y, Mihara E, Ueda H, Sato T, Tokuyama H, Arai H, Asou H, Takagi J, Ishitani R, Nishimasu H, Nureki O, Aoki J. Structure and biological function of ENPP6, a choline-specific glycerophosphodiester-phosphodiesterase. Sci Rep 2016; 6:20995. [PMID: 26888014 PMCID: PMC4757880 DOI: 10.1038/srep20995] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Accepted: 01/14/2016] [Indexed: 11/09/2022] Open
Abstract
Choline is an essential nutrient for all living cells and is produced extracellularly by sequential degradation of phosphatidylcholine (PC). However, little is known about how choline is produced extracellularly. Here, we report that ENPP6, a choline-specific phosphodiesterase, hydrolyzes glycerophosphocholine (GPC), a degradation product of PC, as a physiological substrate and participates in choline metabolism. ENPP6 is highly expressed in liver sinusoidal endothelial cells and developing oligodendrocytes, which actively incorporate choline and synthesize PC. ENPP6-deficient mice exhibited fatty liver and hypomyelination, well known choline-deficient phenotypes. The choline moiety of GPC was incorporated into PC in an ENPP6-dependent manner both in vivo and in vitro. The crystal structure of ENPP6 in complex with phosphocholine revealed that the choline moiety of the phosphocholine is recognized by a choline-binding pocket formed by conserved aromatic and acidic residues. The present study provides the molecular basis for ENPP6-mediated choline metabolism at atomic, cellular and tissue levels.
Collapse
Affiliation(s)
- Junko Morita
- Department of Biological Sciences, Graduate School of Sciences, The University of Tokyo, 2-11-16, Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan
| | - Kuniyuki Kano
- Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3, Aoba, Aramaki, Aoba-ku, Sendai, Miyagi, 980-8578, Japan
| | - Kazuki Kato
- Department of Biological Sciences, Graduate School of Sciences, The University of Tokyo, 2-11-16, Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan
| | - Hiroyuki Takita
- Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3, Aoba, Aramaki, Aoba-ku, Sendai, Miyagi, 980-8578, Japan
| | - Hideki Sakagami
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1, Hongo, Bumkyo-ku, Tokyo, 113-0033, Japan
| | - Yasuo Yamamoto
- Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3, Aoba, Aramaki, Aoba-ku, Sendai, Miyagi, 980-8578, Japan
| | - Emiko Mihara
- Institute for Protein Research, Osaka University, 3-2, Yamadaoka, Suita-shi, Osaka, 565-0871, Japan
| | - Hirofumi Ueda
- Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3, Aoba, Aramaki, Aoba-ku, Sendai, Miyagi, 980-8578, Japan
| | - Takanao Sato
- Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3, Aoba, Aramaki, Aoba-ku, Sendai, Miyagi, 980-8578, Japan
| | - Hidetoshi Tokuyama
- Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3, Aoba, Aramaki, Aoba-ku, Sendai, Miyagi, 980-8578, Japan
| | - Hiroyuki Arai
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1, Hongo, Bumkyo-ku, Tokyo, 113-0033, Japan
| | - Hiroaki Asou
- Center for Kampo Medicine, Keio University School of Medicine, 35, Shinanomachi, Shinjuku-ku, Tokyo, 160-0016, Japan
| | - Junichi Takagi
- Institute for Protein Research, Osaka University, 3-2, Yamadaoka, Suita-shi, Osaka, 565-0871, Japan
| | - Ryuichiro Ishitani
- Department of Biological Sciences, Graduate School of Sciences, The University of Tokyo, 2-11-16, Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan
| | - Hiroshi Nishimasu
- Department of Biological Sciences, Graduate School of Sciences, The University of Tokyo, 2-11-16, Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan.,PRESTO (Precursory Research for Embryonic Science and Technology), JST (Japan Science and Technology Agency), 4-1-8, Honcho, Kawaguchi, Saitama, 332-0012, Japan
| | - Osamu Nureki
- Department of Biological Sciences, Graduate School of Sciences, The University of Tokyo, 2-11-16, Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan.,AMED (Japan Agency for Medical Research and Development)-CREST (Core Research for Evolutional Science and Technology), 1-7-1, Otemachi, Chiyoda-ku, Tokyo, 100-0004, Japan
| | - Junken Aoki
- Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3, Aoba, Aramaki, Aoba-ku, Sendai, Miyagi, 980-8578, Japan.,AMED (Japan Agency for Medical Research and Development)-CREST (Core Research for Evolutional Science and Technology), 1-7-1, Otemachi, Chiyoda-ku, Tokyo, 100-0004, Japan
| |
Collapse
|
8
|
Surlow BA, Cooley BM, Needham PG, Brodsky JL, Patton-Vogt J. Loss of Ypk1, the yeast homolog to the human serum- and glucocorticoid-induced protein kinase, accelerates phospholipase B1-mediated phosphatidylcholine deacylation. J Biol Chem 2014; 289:31591-604. [PMID: 25258318 DOI: 10.1074/jbc.m114.581157] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Ypk1, the yeast homolog of the human serum- and glucocorticoid-induced kinase (Sgk1), affects diverse cellular activities, including sphingolipid homeostasis. We now report that Ypk1 also impacts the turnover of the major phospholipid, phosphatidylcholine (PC). Pulse-chase radiolabeling reveals that a ypk1Δ mutant exhibits increased PC deacylation and glycerophosphocholine production compared with wild type yeast. Deletion of PLB1, a gene encoding a B-type phospholipase that hydrolyzes PC, in a ypk1Δ mutant curtails the increased PC deacylation. In contrast to previous data, we find that Plb1 resides in the ER and in the medium. Consistent with a link between Ypk1 and Plb1, the levels of both Plb1 protein and PLB1 message are elevated in a ypk1Δ strain compared with wild type yeast. Furthermore, deletion of PLB1 in a ypk1Δ mutant exacerbates phenotypes associated with loss of YPK1, including slowed growth and sensitivity to cell wall perturbation, suggesting that increased Plb1 activity buffers against the loss of Ypk1. Because Plb1 lacks a consensus phosphorylation site for Ypk1, we probed other processes under the control of Ypk1 that might be linked to PC turnover. Inhibition of sphingolipid biosynthesis by the drug myriocin or through utilization of a lcb1-100 mutant results in increased PLB1 expression. Furthermore, we discovered that the increase in PLB1 expression observed upon inhibition of sphingolipid synthesis or loss of Ypk1 is under the control of the Crz1 transcription factor. Taken together, these results suggest a functional interaction between Ypk1 and Plb1 in which altered sphingolipid metabolism up-regulates PLB1 expression via Crz1.
Collapse
Affiliation(s)
- Beth A Surlow
- From the Department of Biological Sciences, Duquesne University, Pittsburgh, Pennsylvania 15282 and
| | - Benjamin M Cooley
- From the Department of Biological Sciences, Duquesne University, Pittsburgh, Pennsylvania 15282 and
| | - Patrick G Needham
- the Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15260
| | - Jeffrey L Brodsky
- the Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15260
| | - Jana Patton-Vogt
- From the Department of Biological Sciences, Duquesne University, Pittsburgh, Pennsylvania 15282 and
| |
Collapse
|