Immobilized metal-ion affinity chromatography of peptides on metalloporphyrin stationary phases

The retention of selected dipeptides and tripeptides containing tyrosine was examined. As stationary phase an aminopropylated silica gel loaded with covalently linked tetraphenylporphyrin was used. The effect of metalization of porphyrin with Cu(II) and Zn(II) on retention was investigated. The observed separation is based on a mixed mechanism involving π-π and hydrophobic interactions as well as complex formation between immobilized metal ions and peptides. A satisfactory separation was demonstrated for C-peptide and bovine insulin. The possibility of separation of various insulins was also investigated. Received: 10 August 1998 / Revised: 21 December 1998 / Accepted: 28 December 1998     

On the mathematical modelling of dynamic problems in a micro‐periodic composite material

The aim of this paper is to propose a certain new approach to the formulation of both discrete and continuum models for the analysis of dynamic problems in elastic composite solids with a periodic microstructure. The proposed approach is based on a periodic simplicial division of the unit cell and on the assumption of a uniform strain in every simplex. The main feature of the obtained discrete model is the finite‐difference form of governing equations. By applying smoothing operation the continuum models are derived directly from the discrete ones.     

In vitro protein profiles in the early and late stages of Douglas‐fir xylogenesis

The process of wood formation is of great interest to control and manipulate wood quality for economically important gymnosperms. A Douglas‐fir tissue culture system was developed that could be induced to differentiate into tracheary elements (fibers) making it possible to monitor xylogenesis in vitro by a proteomics approach. Two proteomes were analyzed and compared, one from an early and one from a late stage of the fiber differentiation process. After 18 weeks in a differentiation‐inducing medium, 80% of the callus cells were elongated while 20% showed advanced spiral thickening indicating full wood fiber differentiation. Based on 2D electrophoresis, MS, and data analyses (data are available via ProteomeXchange with identifier PXD001484.), it was shown that in nondifferentiated callus (representing an early stage of development), proteins related to protein metabolism, cellular energy, and primary cell wall metabolism were abundant. By comparison, in cells actively differentiating wood fibers (representing a late stage of development), proteins involved in cell wall polysaccharide biosynthesis predominated together with housekeeping and stress‐associated proteins.     

A comparative survey of proteins from recalcitrant tissues of a non-model gymnosperm, Douglas-fir

Most research in plants and other organisms has, for the sake of convenience, focused on the use of model species to identify mechanisms that are conserved throughout the whole kingdom. Nevertheless, unique features and processes such as those related to plant cell wall and fiber formation, and to wood quality, sometimes need to be studied directly in the non-model organism of interest. Such organisms, like the economically and ecologically important gymnosperm Douglas-fir (Pseudotsuga menziesii), which is one of the crucial softwood timber species in Northern America, are often difficult to investigate. High phenolic, resin, and tannin contents in the woody tissues, as well as an incompletely sequenced genome, have contributed greatly to the species' recalcitrance for molecular biology investigations. In this study, we present a complete procedure detailing protein sample preparation, separation, and proteomic analysis based on cross-species identification of Douglas-fir. Proteins from the cambial zone, mature needles, and in vitro callus were extracted, purified, and separated via 1D and 2D SDS-PAGE. One-dimensional electrophoresis coupled with ESI-MS/MS was used for cross-species protein identification in order to evaluate the potential of this approach and reveal major differences in protein profiles among tested tissues. Identified proteins were functionally and developmentally compared. The likely contribution of these proteins to the properties of the cell wall and wood is indicated and discussed.     

Investigation of natural dyes occurring in historical Coptic textiles by high-performance liquid chromatography with UV-Vis and mass spectrometric detection

Liquid chromatography (LC) combined with ultraviolet-visible (UV-Vis) and mass spectrometric (MS) detection was utilized to study the chemical components present in extracts of natural dyes originating from fiber samples obtained from Coptic textiles from Early Christian Art Collection of National Museum in Warsaw. Chromatographic retention, ionization, UV-Vis and mass spectra of twenty selected dye compounds of flavanoid-, anthraquinone- and indigo-types were studied. Most of the investigated compounds could be ionized by positive and negative ion electrospray ionization. Difficulties with the ionization by electrospray were experienced for indigotin and brominated indigotins, but these were ionized by atmospheric pressure chemical ionization. Mass spectrometric detection, utilizing different scanning modes of a triple quadrupole mass spectrometer, combined with the UV-Vis detection was demonstrated to be a powerful approach to detection and identification of dyes in the extracts of archeological textiles. Using this approach the following compounds were identified in the extracts of Coptic textiles: luteolin, apigenin, rhamnetin, kaempferol, alizarin, purpurin, xanthopurpurin, monochloroalizarin, indirubin, and so the type of dye that was utilized to dye the textiles could be identified. Detection capabilities for several dye-type analytes were compared for the UV-Vis and mass spectrometric detection. The signal-to-noise ratios obtained for luteolin, apigenin, and rhamnetin were higher for the MS detection for most of the examined sample extracts. Purpurin, alizarin, and indirubin showed similar signal-to-noise ratios for UV-Vis and mass spectrometric detection.     

Identification of natural dyes in archeological Coptic textiles by liquid chromatography with diode array detection

Reversed-phase HPLC with diode-array UV-Vis spectrophotometric detection has been used for identification of natural dyes in extracts from wool and silk fibres from archeological textiles. The examined objects originate from 4th to 12th Century Egypt and belong to the collection of Early Christian Art of the National Museum in Warsaw. Extraction from fibres was carried out with HCl solution containing ethanol or with warm pyridine. As the main individual chemical components of natural dyes, anthraquinone, indigoid and flavonoid dyes including alizarin, purpurin, luteolin, apigenin, carminic acid, ellagic acid, gallic acid, laccaic acids A and B and indigotin were found. For pyridine extracts another mobile phase with an optimized gradient of organic modifier concentration was used. With such an eluent the appearance of double peaks for indigotin and indirubin was eliminated. For acidic extraction of dyes from fibres, ethanol was used. Due to its higher boiling point than methanol it evaporates slower from the extraction solution enabling a more efficient extraction of dyes.