Search

A three-stage linear gradient strategy using reverse-phase high-performance liquid chromatography (HPLC) was optimized for rapid, high-quality, and simultaneous purification of the lipopeptide isoforms of iturin, fengycin, and surfactin, which may differ in composition by only a single amino acid and/or the fatty acid residue. Matrix-assisted laser desorption ionization time-of-flight tandem mass spectrometry (MALDI-TOF-MS/MS) was applied to detect the lipopeptides harvested from each reversed-phase HPLC peak. Amino acid analysis based on phenyl isothiocyanate derivatization was further used for confirmation of the amino acid species and molar ratio in a certain HPLC fraction. By this MALDI-TOF-MS/MS coupled with amino acid analysis, it was revealed that iturin at m/ z 1,043 consists of a circular Asn-Tyr-Asn-Gln-Pro-Asn-Ser peptide and C β-OH fatty acid. Surfactin homologs from Bacillus subtilis THY-7 at m/ z 1,030, 1,044, 1,058, and 1,072 possess a circular Glu-Leu-Leu-Val-Asp-Leu-Leu peptide and the β-OH fatty acid with a different length (C-C). Fengycin species at m/ z 1,463 and 1,477 are homologs possessing the circular peptide Glu-Orn-Tyr-Thr-Glu-Ala-Pro-Gln-Tyr-Ile linked to a C or C γ-OH fatty acid, whereas fengycin at m/ z 1,505 contains a Glu-Orn-Tyr-Thr-Glu-Val-Pro-Gln-Tyr-Ile sequence with a Val instead of Ala at position 6. The method developed in this work provided an efficient approach for characterization of diverse lipopeptide isoforms from the iturin, fengycin, and surfactin families. [ABSTRACT FROM AUTHOR]

A methodology to purify a Ho solution has been developed by a combination of activity and mass concentration measurements in order to further determine the Ho half-life. The isobaric interference at m/ q ≃ 166 requires Ho purification from non-natural Er with a high purification degree due to the large amount of Ho as opposed to Er. The Ho/Er separation was achieved using high-performance liquid chromatography on a semi-preparative column followed by purification on gravitational chromatography. The efficiency of the separation was evaluated after precise determination of the Er isotopic composition. The purification methodology enabled to separate Ho from Er. [ABSTRACT FROM AUTHOR]

To achieve an efficient separation and purification of α-L-rhamnosidase (Rha) from naringinase (Nar) that was prepared from a fermented broth of Aspergillus niger, improved experimental methods were developed with aid of a chemical dithiothreitol (DTT) and a novel HPLC method. The addition of DTT did not negatively affect the purification of Rha and Nar, but greatly simplified the purification steps due to its strong capability of separating the Rha from Nar. The novel HPLC method enabled simultaneous measurement and differentiation of the Rha and the Nar with the naringin as the substrate. These improvements resulted in an efficient purification of the homogenous Rha with an estimated molecular weight of 87 kDa. Otherwise, Rha could not be extracted with enough purity even by the combination of sulphate precipitation, ion exchange chromatography and gel filtration chromatography. The modified methods have ensured efficient purification of the Rha from A. niger naringinase. This study provides a powerful and simple procedure to separate and purify the Rha of Nar, which will facilitate further more in-depth studies of these enzymes, as well as their industrial applications. [ABSTRACT FROM AUTHOR]

Abstract  A facile and fast approach for the purification of deoxycytidine kinase (dCK) from calf thymus was developed using a fast performance liquid chromatography system. A 73-fold enrichment of the enzyme was noted compared to unfractionated dCK. Characterization studies demonstrated that dCK had a molecular mass of 31 kDa using SDS–PAGE, an optimum pH of 7.0 and the enzyme maintained stability between 30 and 40°C. The rapid preparation of dCK demonstrated here will be valuable in the synthesis of nucleotide analogs. [ABSTRACT FROM AUTHOR]

The naturally occurring octacyclopeptide brachystemin F was synthesized for the first time in the present study by a two-step solid-phase/solution strategy. All the amino acids in this study have the L-configuration. The linear octapeptide was assembled by standard Fmoc solid-phase peptide synthesis (SPPS), and subsequent cyclization was carried out by the solution method. The target compound was purified by preparative RP-HPLC, and its structure was identified by H NMR, C NMR, and MS. [ABSTRACT FROM AUTHOR]

The article discusses the characterization of the olfactory receptors in mice which are used to attract female mice by male counterparts. It mentions that fractionation and purification of compounds through high performance liquid chromatography bioassays revealed that tetradecen-1-ol chemical compound present in urine of male mice is responsible for attraction of female mice. It highlights that olfactory receptors of mice are also used for detection of volatile chemicals in environment.