L his

Manufactured by Merck Group

Sourced in United States

L-His is a laboratory equipment product manufactured by Merck Group. It is used for the measurement and analysis of histidine, an amino acid essential for various biological processes. The core function of L-His is to provide accurate and reliable data on histidine levels in samples. No further interpretation or extrapolation on the intended use of this product is provided.

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L-histidine (His) (5 citations) L-histidine (L-His, (2 citations)

6 protocols using l his

Bacterial Zinc Uptake Assay

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Overnight cultures of bacteria were diluted 1:50 in LB and grown at 37 °C for 1 h. These cultures were re-seeded 1:100 in 10 mL CP media plus or minus 150 µg/mL CP for 6 h. Cells were normalized to the same OD₆₀₀, pelleted, and suspended in 1 mL 50 mM Tris-HCl, pH 7.5, 1 mM MgCl₂. His-Zn complexes were prepared by incubating 1 mM L-His (Sigma) and 500 µM Zn⁷⁰ or 500 µM Zn⁷⁰ alone in 5 mL of 50 mM Tris-HCl, pH 7.5 for 30 min. Buffer only, Zn⁷⁰, or His-Zn complexes were diluted 1:10 into the bacterial samples and incubated for 30 min. Uptake was quenched with 1 mL ice cold ethanol:acetone (1:1) and incubated 10 min on ice. Cells were pelleted and washed twice with Milli-Q water. Samples were then suspended in 0.5 mL Milli-Q water and 1 mL of 50% Optima Ultra-pure nitric acid (Fisher), incubated overnight at 50 °C, and then diluted in Milli-Q water to 10 mL. ICP-MS was performed on a Perkin-Elmer DRCII ICP-MS equipped with AS-93 autosampler and DRC cell as outlined in our previous work (Jacobsen et al., 2011 (link)).

Nairn B.L., Lonergan Z.R., Wang J., Braymer J.J., Zhang Y., Calcutt M.W., Lisher J.P., Gilston B.A., Chazin W.J., de Crécy-Lagard V., Giedroc D.P, & Skaar E.P. (2016). The response of Acinetobacter baumannii to Zinc starvation. Cell host & microbe, 19(6), 826-836.

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Quantitative Determination of Urocanic Acid

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0.5~2 µM purified HutH (see Supplemental Experimental Procedures) was incubated with various concentrations of L-His (Sigma) (25 mM HEPES, 100 mM KCl, 3 mM TCEP, pH 7.5, with Zn or chelator) for 3 min at ambient temperature. Reactions were quenched with 3-fold HPLC running buffer A (2% MeOH, 98% water, 0.1% TFA). Samples were run though a spin column to remove proteins and injected onto a Kinetex C18 reverse phased column (Phenomenex XB-C18 100 Å) on a Waters 600 HPLC system equipped with a Waters 717 plus auto-sampler and Waters 486 tunable absorbance detector. Following injection, the HPLC was run as follows: 0–5 min 0% buffer B (95% MeOH, 5% water, 0.1% TFA), 5–15 gradient to 100% buffer B, 15–18 min, 100% buffer B, 18–20 min gradient to 0% buffer B. Urocanic acid was detected by absorbance at 277 nm with concentration determined from the integrated peak areas by comparison to a standard curve of urocanic acid (Aldrich).

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Assessing Reactive Species Impact on Bacterial Viability

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The scavengers used was sodium chromate (Cr(VI)), 2.5 mM, Sigma, 99.5%) for electron, superoxide dismutase (400 U mL⁻¹, Sigma, 99%)) for •O₂⁻, l-histidine for ¹O₂ (l-His, 2.5 mM, Sigma, 99%), catalase for H₂O₂ (300 U mL⁻¹, Sigma), isopropanol (2.5 mM, Sigma, 99.5%) for •OH and sodium oxalate (2.5 mM, Sigma, 99.5%) for hole. The scavengers were added into the bacteria suspension before illumination. The concentrations of bacteria in solution were measured at different time intervals by using standard spread plating techniques. Each sample was serially diluted and each dilution was plated in triplicate onto nutrient agar and incubated at 37 °C for 20 h.

Li P., Li J., Feng X., Li J., Hao Y., Zhang J., Wang H., Yin A., Zhou J., Ma X, & Wang B. (2019). Metal-organic frameworks with photocatalytic bactericidal activity for integrated air cleaning. Nature Communications, 10, 2177.

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Biogenic Amine and Amino Acid Analysis

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BA standards (tyramine hydrochloride, 2-phenylethylamine hydrochloride, putrescine dihydrochloride, cadaverine dihydrochloride, histamine dihydrochloride, tryptamine hydrochloride, spermidine trihydrochloride) and amino acid standards (L-Asp, L-Glu, L-Ser, L-Gly, L-His, L-Thr, L-Arg, γ-aminobutyric acid [GABA], L-Ala, L-Pro, L-Tyr, L-Val, L-Met, L-Iso, L-Leu, L-Phe, L-Trp, and L-Lys) were all purchased from Sigma-Aldrich Chemical Co. (St. Louis, MO, USA). Dansyl chloride, perchloric acid, sodium hydrogen carbonate, potassium dichromate, and silver nitrate were purchased from Daejung Chemical Co. (Siheung, Korea). Distilled water, acetone, and acetonitrile (HPLC grade) were purchased from Tedia Co. (Fairfield, OH, USA).

Shi B, & Moon B. (2024). Effects of soybean cultivar and starter strain on biogenic amines formation during Cheonggukjang fermentation. Food Chemistry: X, 22, 101280.

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Substrate-dependent Amino Acid Transport Assay

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Oocyte recordings were performed in ND100 medium (100 mM NaCl, 2 mM KCl, 1 mM MgCl₂, and 1.8 mM CaCl₂) buffered with 5 mM 2-(N-morpholino)ethanesulfonic acid (MES)-NaOH to pH 5.00, unless stated otherwise. L-Arg, L-Lys, or L-His (Sigma-Aldrich) were added as monohydrochloride salts. For substrate-free solutions, the amino acid was replaced by NMDG hydrochloride (Sigma-Aldrich) to keep the chloride concentration and osmolarity unchanged. The maximum concentration of NMDG used (20 mM) had no effect on PQCL2 and endogenous currents. For patch-clamp recordings in HEK293T cells, the substrate-free external solution contained the following: 130 mM NaCl, 5 mM KCl, 2 mM CaCl₂, 1 mM MgCl₂, 20 mM glucose, 20 mM NMDG-Cl, and 20 mM MES adjusted to pH 5.00 with NaOH or HCl (osmolarity: 315 to 330 mOsm). For substrate application, NMDG was replaced by 20 mM Lys, Arg, or His. The micropipette solution contained the following: 130 mM CsCl, 10 mM ethylene glycol-bis(β-aminoethyl ether)-N,N,N′,N′-tetraacetic acid (EGTA), 2 mM CaCl2, 2 mM MgCl2, and 10 mM Hepes adjusted to pH 7.35 to 7.40 with KOH or HCl, supplemented with 20 mM NMDG, Arg, or Lys (osmolarity: 295 to 305 mOsm). L-[2,3,4-³H]arginine monhydrochloride (specific activity: 40 to 50 Ci/mmol) was from Perkin-Elmer.

Leray X., Conti R., Li Y., Debacker C., Castelli F., Fenaille F., Zdebik A.A., Pusch M, & Gasnier B. (2021). Arginine-selective modulation of the lysosomal transporter PQLC2 through a gate-tuning mechanism. Proceedings of the National Academy of Sciences of the United States of America, 118(32), e2025315118.

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Biomolecular Interactions in Bicine Buffer

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PLP, L-Ser, L-His, L-Trp, indole, indoline, benzimidazole (BZI), CsCl, and 2-AP were purchased from Sigma-Aldrich. Bicine was bought from Thomas Scientific. Unless mentioned otherwise, all solution studies were conducted at 22 ± 3°C and maintained at pH 7.8 in 0.05 M Bicine CsCl buffer containing 1 mM EDTA.

Ghosh R.K., Hilario E., Liu V., Wang Y., Niks D., Holmes J.B., Sakhrani V.V., Mueller L.J, & Dunn M.F. (2021). Mutation of βGln114 to Ala Alters the Stabilities of Allosteric States in Tryptophan Synthase Catalysis. Biochemistry, 60(42), 3173-3186.

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