Protein A chromatography resin lifetime—impact of feed composition

Adsorbent lifetime during protein A chromatography is not readily predicted or understood, representing a key challenge to be addressed for biopharmaceutical manufacturers. This article focuses on the impact of feed composition on the performance of a typical agarose‐based protein A resin across a lifetime of 50 cycles. Cycling studies were performed using three different feed materials with varying levels of feed components including proteases, histones, DNA, and nonhistone proteins. Changes in the process and quality attributes were measured. The DBCs were not seen to vary between conditions although there was a reduction in particle porosity in all cases. Fluorescence spectroscopy and LC‐MS/MS were used to identify the contribution and extent of fouling to the observed capacity loss. Residual protein A ligand density and deposition of foulants (HCP, residual mAb, and DNA) varied between the three feed materials. Resins cycled in feed materials containing high concentrations of HCP and histones were seen to have greater extents of capacity loss. The mode of performance loss, capacity loss, or impact on product quality was seen to vary depending on the feed material. The results indicate that feed material composition may be correlated to the rate and mode of resin aging as a basis for improved process understanding. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 34:412–419, 2018     

Chemotaxonomy of the genus Xanthorrhoea

It was found that the composition of the resins produced by members of the genus Xanthorrhoea was sufficiently taxon-specific to allow the setting up of a chemotaxonomic key. A generalized procedure for the isolation of flavanoids from Xanthorrhoea resins is given together with details of all isolated components.     

Indices of plant N availability in an alpine grassland under elevated atmospheric CO2

The objective of this study was to estimate whether elevated atmospheric [CO₂] alters plant N availability in a native high-elevation grassland in the Swiss Alps using two integrative, relatively non-disruptive methods. Estimates based on seasonal net plant N uptake, and those based on the amounts of NH ₄ ⁺ -N plus NO ₃ ^– -N captured by ion exchange resin (IER) bags, did not differ in plots treated with ambient (355 L L^–1) and elevated (680 L L^–1) [CO₂] in either the second (1993) or third (1994) growing season under treatment with elevated [CO₂]. The results of this study suggest that the effects of rising atmospheric [CO₂] on plant N availability may be negligible in this grassland. The results also contrast the relatively large effects of elevated atmospheric [CO₂] (increases and decreases) reported for highly disturbed artificial systems.     

Development of a boron buffered solution culture system for controlled studies of plant boron nutrition

Chelated-buffered nutrient solutions are used for studies on micronutrient metals but so far no equivalent system exists for boron nutrition studies: the present investigation was initiated with that intention. From a literature review, it was noted that a range of substances form chelates with boron including polyhydric alcohols, sugars and phenolic compounds. However, none apart from hydrofluoric acid formed chelates with formation constants comparable to those of micronutrient metal chelates like diethylenetriaminepentaacetic acid (DTPA). Moreover, most chelating substances had deleterious side effects which reduced their possible use in water culture: many of the compounds are substrates for bacterial growth, some are harmful to handle, and others are toxic to plants or humans. Borosilicate glass; was tested in a laboratory experiment but found to release boron too slowly into solution to maintain constant boron concentration in solution even when very finely ground. Current investigations centre around the use of a boron-specific resin, which strongly complexes H₃BO₃ on its N-methyl glucamine functional groups. The boron sorption capacity of the resin varied from 2.2 to 5.0 mg B g^-1 resin. Boron saturated resin maintained an equilibrium solution boron concentration of 46 t M when added at the rate of 2 g of resin to 1 L of boron free triple deionised water. Plants grown in complete nutrient solution with boron saturated resin added at 1 g per litre of nutrient solution grew as well as plants grown in conventional nutrient solution containing 9.2 t M boron and their shoots contained adequate boron concentrations for growth. There was no evidence that the resin had effects on plant growth other than in releasing and equilibrating boron concentration in the nutrient solution.     

Flavonoids from the external leaf resins of four hemizonia species (asteraceae)

The external leaf resins of four Hemizonia species afforded nine methylated flavonoids, including flavanones, flavones and flavonols. Besides the rare compounds 7-methyleriodictyol and 3,6,8-trimethoxy-5,7,3′,4′-tetrahydroxyflavone the new 6-methoxy-5,7,8,3′,4′-pentahydroxyflavone was isolated and identified by spectroscopic means.     

Minor components of ponderosa pine oleoresin

Esters of ferulic acid with monoterpene alcohols were found in ponderosa pine oleoresin. These colorless ferulic acid esters are responsible for a yellow band seen on DEAE-Sephadex fractionation of the oleoresin. Two diterpene resin acids not previously found in pines and several resin acid artifacts were identified.     

Promoting Green Innovation or Prolonging the Existing Technology

Abstract: A case study of the chlor-alkali industry in Western Europe and Japan is presented examining the effects of environmental regulation on technological change. In Western Europe, standards were set for mercury emissions from chlor-alkali plants, which were gradually tightened subsequently. Research and development (R&D) efforts were directed to end-of-pipe technologies as well as process improvements for reducing mercury emissions, rather than to clean technologies, which eliminate mercury from within the production process. With a significant reduction in mercury emissions with end-of-pipe technologies, new plants continued to be built that relied on the mercury process. As long as these relatively new plants could be utilized, technological transition to the clean ion-exchange membrane process remained slow. The success in reducing mercury emissions with end-of-pipe technologies, in effect, helped to prolong the lifetime of the existing mercury process. In Japan, the government introduced policies to phase out the existing mercury process. The strict approach encouraged innovative companies to make R&D efforts on clean technologies, instead of end-of-pipe technologies for pollution abatement. Applied in a hasty and inflexible way, however, the stringent regulation initially induced most of the chlor-alkali producers to choose the diaphragm process, which later turned out to be inappropriate. After the regulatory schedule was modified to allow more time for process conversion, the remaining mercury-based plants were converted directly to the most efficient ion-exchange membrane process. The technological transition, however, was costly, as most of the diaphragm-based plants introduced following the regulatory mandate were operated only for a short period of time, with the large investment wasted.     

Study of the effect of the peptide loading and solvent system in SPPS by HRMAS-NMR.

The SPPS methodology has continuously been investigated as a valuable model to monitor the solvation properties of polymeric materials. In this connection, the present work applied HRMAS-NMR spectroscopy to examine the dynamics of an aggregating peptide sequence attached to a resin core with varying peptide loading (up to 80%) and solvent system. Low and high substituted BHAR were used for assembling the VQAAIDYING sequence and some of its minor fragments. The HRMAS-NMR results were in agreement with the swelling of each resin, i.e. there was an improved resolution of resonance peaks in the better solvated conditions. Moreover, the peptide loading and the attached peptide sequence also affected the spectra. Strong peptide chain aggregation was observed mainly in highly peptide loaded resins when solvated in CDCl3. Conversely, due to the better swelling of these highly loaded resins in DMSO, improved NMR spectra were acquired in this polar aprotic solvent, thus enabling the detection of relevant sequence-dependent conformational alterations. The more prominent aggregation was displayed by the VQAAIDYING segment and not by any of its intermediary fragments and these findings were also corroborated by EPR studies of these peptide-resins labelled properly with an amino acid-type spin probe.     

Authors index

In a runoff irrigation system in Northern Kenya, we studied the nutrient interactions of sole cropped and alley cropped Sorghum bicolor (L.) Moench and Acacia saligna (Labill.) H.L. Wendl. The trees were pruned once before the cropping season and the biomass was used as fodder for animals. The nutrient contents in leaf tissue, soil and soil solution were monitored and the uptake of applied tracers (¹⁵N, Sr) was followed. The grain yield of alley cropped sorghum was similar to or slightly higher than in monoculture and did not decrease near the tree-crop interface. Foliar N and Ca contents of the crop were higher in the agroforestry combination than in monoculture, corresponding to higher soil N and Ca contents. Soil solution and soil mineral N dynamics indicate an increase of N under the tree row and unused soil N at the topsoil in the alley of the sole cropped trees as well as below 60 cm depth in the crop monoculture. The N use efficiency of the tree+crop combination was higher than the sole cropped trees or crops. Competition was observed for Zn and Mn of both tree and crop whereas for Ca only the tree contents decreased. P, K, Mg and Fe dynamics were not affected by alley cropping at our site. The lower uptake of applied Sr by trees in alley cropping compared to those of the monoculture stand suggested a lower competitiveness of the acacia than sorghum, which did not show lower Sr contents when intercropped. The study showed the usefulness of combining soil and plant analyses together with tracer techniques identifying nutrient competition, nutrient transfer processes and the complementary use of soil nutrients, as the main features of the tree-crop combination. This revised version was published online in June 2006 with corrections to the Cover Date.