Leucine enkephalin leu enk

Manufactured by Waters Corporation

Sourced in Belgium, United Kingdom

Leucine-enkephalin (leu-enk) is a synthetic peptide used as a reference standard in analytical procedures. It is a pentapeptide with the sequence Tyr-Gly-Gly-Phe-Leu. Leu-enk is commonly used to calibrate and validate analytical instruments and techniques, particularly in the field of mass spectrometry.

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Lab products found in correlation

Sodium formate, by Merck Group (2 mentions) Lc ms grade formic acid, by Thermo Fisher Scientific (1 mentions) Integral 3 system, by Merck Group (1 mentions) Verapamil, by Merck Group (1 mentions) Buspirone, by Merck Group (1 mentions) Cm3050s cryostat, by Leica (1 mentions) Synapt g2 si q tof, by Waters Corporation (1 mentions) Hdi software, by Waters Corporation (1 mentions) Oasis hlb, by Waters Corporation (1 mentions) Sodium hydroxide (naoh), by Merck Group (1 mentions) Formic acid, by Avantor (1 mentions) Methanol and acetonitrile hplc grade, by Thermo Fisher Scientific (1 mentions) Acetonitrile, by Thermo Fisher Scientific (1 mentions)

Close spelling variants of this product

Leucine enkephalin (55 citations)

4 protocols using leucine enkephalin leu enk

ALD-Coated Glass Slide Preparation

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TiO₂-coated glass slides were created by atomic layer deposition of titanium(IV) isopropoxide on glass; the full procedure has been reported elsewhere [20 (link)]. Verapamil, buspirone, and titanium(IV) oxide nanopowder P25 were obtained from Sigma-Aldrich (Zwijndrecht, The Netherlands). Testosterone, ostarine, and andarine were kindly donated by RIKILT (Wageningen, The Netherlands). Ultrapure water (H₂O)—18.2 MΩ × cm⁻¹ at 25 °C—was freshly produced daily with a Millipore (Molsheim, France) Integral 3 system. Acetonitrile (ACN) LC-MS grade was bought from VWR (Leuven, Belgium). Methanol (MeOH) UPLC-MS grade was purchased from Biosolve (Valkenswaard, The Netherlands). Formic acid (FA) LC-MS grade was bought from Fisher Scientific (Geel, Belgium) and leucine-enkephalin (leu-enk) for lock mass-corrected mass calibration was purchased from Waters (Manchester, UK).

van Geenen F.A., Franssen M.C., Miikkulainen V., Ritala M., Zuilhof H., Kostiainen R, & Nielen M.W. (2019). TiO2 Photocatalyzed Oxidation of Drugs Studied by Laser Ablation Electrospray Ionization Mass Spectrometry. Journal of the American Society for Mass Spectrometry, 30(4), 639-646.

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DESI-MS Imaging of Lung Metabolites

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DESI-MS, an ambient ionization imaging technique, was performed to detect metabolites and their spatial distributions in situ. Prior to data acquisition, murine lungs were embedded in 2% carboxymethylcellulose (CMC, w/v, Sigma, 419273) (Nguyen et al., 2018 (link); Stoeckli et al., 2007 (link)), sectioned to 10 μm thickness using a Leica CM3050 S cryostat (Columbia University Molecular Pathology Shared Resource (MPSR) histology service) and stored at −80°C. The frozen 10 μm lung tissues were dried for 20 min at 300 torr using a vacuum dessicator (Bel-Art). Briefly, DESI-MS was performed in the negative ion mode (−0.6 kV) from m/z 50–1000 using the Waters Synapt G2-Si QTOF coupled to a Waters DESI source with a motorized stage. The lung tissues were scanned under charged droplets generated from the electrospray nebulization of a histologically compatible solvent, methanol:acetonitrile 1:1 (v/v) containing 40 pg/μl of the internal standard leucine enkephalin (Leu-Enk) (Waters Corp.), that is used as a lock mass to correct any mass drifts during imaging runs (flow rate 1.5 μl/min). Raw MS files are processed using the HDI software (version 1.5, Waters Corp.) or exported to imzML (Schramm et al., 2012 (link)) to be used in SCiLS Lab MVS Pro (2020 version).

Wong Fok Lung T., Charytonowicz D., Beaumont K.G., Shah S.S., Sridhar S.H., Gorrie C.L., Mu A., Hofstaedter C.E., Varisco D., McConville T.H., Drikic M., Fowler B., Urso A., Shi W., Fucich D., Annavajhala M.K., Khan I.N., Oussenko I., Francoeur N., Smith M.L., Stockwell B.R., Lewis I.A., Hachani A., Baskota S.U., Uhlemann A.C., Ahn D., Ernst R.K., Howden B.P., Sebra R, & Prince A. (2022). Klebsiella pneumoniae induces host metabolic stress that promotes tolerance to pulmonary infection. Cell metabolism, 34(5), 761-774.e9.

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Analytical Standards and Sample Preparation Protocol

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Analytical standards (purity >98%) were purchased from Cluzeau Info Labo (CIL, Sainte-Foy-La Grande, France), TechLab (Metz, France), Sigma-Aldrich (Saint-Quentin Fallavier, France), and LGC standard (Molsheim, France).
The acetonitrile and methanol (HPLC grade) used for extraction were purchased from Fisher Chemical (Ilkirch, France). Ultrapure water was produced using a Millipore Direct-Ultrapure Water System. Oasis® HLB (divinylbenzene/N-vinylpyrrolidone copolymer) extraction cartridges (500 mg, 6cc, 60 µm) were purchased from Waters Corporation (Guyancourt, France). Empty polypropylene SPE tubes with polyethylene frits were supplied by Supelco (Saint-Quentin Fallavier, France). The POCIS were purchased from Exposmeter SA (Tavelsjö, Sweden). Their pharmaceutical configuration consists of two 0.1-µm PolyEther Sulfone (PES) membranes containing Oasis® HLB sorbent.
The solvents used for the HPLC-HRMS analysis included acetonitrile and water (UPLC/MS grade) purchased from Biosolve (Dieuze, France), and formic acid (99%, LC/MS grade) purchased from Avantor (Deventer, the Netherlands). The lock mass used as an internal reference in the mass spectrometer's ionization source, Leucine Enkephalin (LeuEnk), was purchased from Waters Corporation and the calibrant for the mass spectrometer, sodium formate, was prepared with sodium hydroxide, purchased from Sigma Aldrich.

Soulier C., Coureau C, & Togola A. (2016). Environmental forensics in groundwater coupling passive sampling and high resolution mass spectrometry for screening. The Science of the total environment, 563-564.

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Melphalan Handling and Characterization

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Caution: melphalan, degradation products and oligomers are carcinogenic and should be handled with care.
2.1 Chemicals Melphalan (Mel; min. 95 %) and sodium formate (HPLC, > 99.0 %) were purchased from Sigma-Aldrich (Bornem, Belgium). Acetonitrile (ACN; HPLC grade for gradient analysis) and formic acid (FA; 99+ %) were obtained from Acros (Geel, Belgium). Reverse osmosis (RO) water was prepared using a Silex water filtering system from Eurowater (Nazareth-Eke, Belgium). Leucine Enkephalin (Leu-Enk) was obtained from Waters (Manchester, UK).

Boschmans J., Lemière F, & Sobott F. (2017). Analyzing complex mixtures of drug-like molecules: Ion mobility as an adjunct to existing liquid chromatography-(tandem) mass spectrometry methods. Journal of chromatography. A, 1490.

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