Jasper D.H van Heemst

Encapsulation of protein in humic acid from a histosol as an explanation for the occurrence of organic nitrogen in soil and sediment

Recent work suggests that nitrogen in humic acids exists primarily as amide functional groups that mirror those in protein. However, the mode for the existence of such labile materials as protein still remains unclear. With the combined applications of NMR spectroscopy, tetramethylammonium hydroxide (TMAH) thermochemolysis, pyrolysis/GC/MS, and elemental analysis, we propose that the survival of proteins in humic acids is carried out by encapsulation into hydrophobic domains of humic acids. To test this hypothesis, we simulated encapsulation of 15N-labeled protein extracts into humic acids and demonstrated that complete hydrolysis of the protein is prevented by the encapsulating humic acid. Results from this study constitute evidence to support the encapsulation mechanism involved in the formation of refractory organic nitrogen during sediment diagenesis.

Laser Micropyrolysis GC-MS of lignin

Abstract The potential for using lasers as a highly directional thermal source in analytical pyrolysis studies is further investigated by the laser micropyrolysis GC–MS analysis of lignin moieties. Two woods representative of the main types of lignin (i.e. gymnosperm/guaiacyl producing and angiosperm/syringyl and guaiacyl producing) were separately analysed by both laser micropyrolysis GC–MS and the longer used pyroprobe pyrolysis GC–MS. High levels of correlation were observed from the laser and pyroprobe pyrograms of both lignins.

Multiple sources of alkylphenols produced upon pyrolysis of DOM, POM and recent sediments

Abstract This study focuses on the different precursors of simple alkylphenols in pyrolyzates of different types of organic matter. Several organic matter samples were studied, i.e. dissolved organic matter (DOM), particulate organic matter (POM), sediments, polysaccharide/protein standards, algae, hydrolyzable tannins, lignins, lignites, coals, soils and insect cuticles. Most samples were subjected to saponification and some to hydrolysis using hydrochloric acid. Distribution patterns of the alkylphenols in the pyrolyzates were compared with those in pyrolyzates of natural samples. To some extent, the distribution patterns of these alkylphenols can be used to discriminate their precursors, lignins, protein and transformed protein. Alkylphenols in pyrolyzates of samples like DOM, POM and sediments are probably reflecting polymers which are formed by cross-linking of protein units (tyrosine) forming non-amide bonds on hydrolysis of polysaccharide/protein material in the water column. The polysaccharide part plays a major role in the formation of these polymers.

Preservation of algaenan and proteinaceous material during the oxic decay of Botryococcus braunii as revealed by pyrolysis-gas chromatography/mass spectrometry and 13C NMR spectroscopy

Botryococcus braunii cells were grown until the late-stationary phase of growth and subsequently decomposed under oxic conditions for 201 days using a microbial consortium obtained from a freshwater lake.Degradation exhibited multi-G model kinetics, with a ‘labile’ fraction lost at a rate two to three times slower than those observed for the degradation of other previously studied phytoplankton, and a ‘refractory’ fraction lost even more slowly.Scanning electron microscopy of the 201-day detritus, as previously seen for the kerogen, indicates the preservation of cell wall material with loss of intracellular contents.Detrital samples analyzed by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and solid-state ramp-CPMAS 13 C NMR, however, indicates the preservation of highly aliphatic material, algaenan, as well as ‘intrinsically labile’ proteinaceous components.These results further support the encapsulation hypothesis that proteins may be sterically protected from enzymatic attack via intimate associations with refractory, macromolecular organic matter. # 2003 Elsevier Science Ltd.All rights reserved.

Characterization of amino acids and proteinaceous materials using online tetramethylammonium hydroxide (TMAH) thermochemolysis and gas chromatography-mass spectrometry technique

Abstract An on-line thermochemolysis technique using tetramethylammonium hydroxide (TMAH) for the characterization of amino acids and proteinaceous materials was developed. Amino acids were converted to their corresponding N -and O -methyl derivatives by TMAH in the pyrolysis chamber for 15 s at 300°C prior to separation and detection by gas chromatography-mass spectrometry. Thermochemolysis reactions of TMAH with protein and macromolecular environmental sample were also performed. Results show that the peptide bonds were effectively cleaved by thermochemolysis reaction, yielding individual amino acid methyl esters. Thus, this on-line TMAH thermochemolysis technique is an easy and efficient method for the characterization of amino acids and proteinaceous materials.

Nature, origin and average age of estuarine ultrafiltered dissolved organic matter as determined by molecular and carbon isotope characterization

The Ems-Dollart estuary (on the border of the Netherlands and Germany) was chosen for a pilot study to characterize ultrafiltered dissolved organic matter (UDOM) in estuarine systems. UDOM samples were taken from four locations with salinities varying from 0.43 to 20 parts per thousand. The UDOM in these samples was concentrated using cross-flow ultrafiltration and represents the size fraction of DOM between 1000 Dalton and 0.2 mu m. The samples were analyzed by analytical pyrolysis, stable carbon isotope and radiocarbon analysis, and solid state C-13 NMR, All UDOM samples throughout the estuary showed relatively similar pyrolyzates and C-14 activities (c. 87%). Solid-state C-13 NMR spectra were also similar, except for the sample with the highest salinity. UDOM delta(13)C values ranged from -27.78 to -25.40 parts per thousand with increasing salinity. This suggests mixing of river DOM with seawater DOM of comparable ages. The absence of pyrolysis products of unaltered polysaccharides, lignins, proteins and lipids indicates that the Ems-Dollart estuary UDOM consists of a large fraction of refractory organic matter and a very small fraction of fresh organic matter

Novel algal polyphenolic biomacromolecules as significant contributors to resistant fractions of marine dissolved and particulate organic matter

Abstract To investigate whether novel polyphenolic constituents, that have been reported to contribute considerably to dissolved organic matter (DOM) and particulate organic matter (POM), are of algal origin, a number of algae, i.e. the brown macroalgae Nereocystis luetkeana, Fucus gardneri, Costaria costata, Sargassum muticum , a green macroalga Ulva fenestrata , a red macroalga Opuntiella californica and a microalga Rhodomonas sp., were subjected to analytical pyrolysis. The freeze-dried algae were extracted and saponified. In the case of N. luetkeana and U. fenestrata proteins and carbohydrates were removed by acid treatments with HCl and H 2 SO 4 . All fractions were analysed by Curie-point pyrolysis-gas chromatography-mass spectroscopy (CuPy-GC-MS). Alkylphenols were encountered in the pyrolysates of all algae, and in the residues obtained after acid treatment of N. luetkeana and U. fenestrata . It is thought that these alkylphenols are generated from possibly alkylated phlorotannin-type compounds. Though non-alkylated phlorotannins are known to occur almost exclusively in brown macroalgae, these postulated alkylated counterparts occur in both brown macroalgae and other algae. Their selective preservation during water column transport causes a significant enrichment of these substances in DOM and POM.

Alternative biological sources for 1,2,3,4-tetramethylbenzene in flash pyrolysates of kerogen

Pyrolysates of kerogens isolated from Indian Ocean surface sediments and from Black Sea Unit II contain abundant 1,2,3,4-tetramethylbenzene (1,2,3,4-TMB) suggesting the presence of macromolecularly-bound isorenieratane skeletons derived from isorenieratene biosynthesized by green sulphur bacteria (cf. Hartgers et al., 1994c). However, the 13C content of 1,2,3,4-TMB is identical to that of algal lipids, excluding an origin from green sulphur bacteria. The presence of 1,2,3,4-TMB in pyrolysates of stable residues of several marine algae indicates that it can also have an algal origin. Therefore, the assessment of photic zone anoxia on the basis of the abundant presence of 1,2,3,4-TMB in the pyrolysate is not possible without determination of its stable carbon isotopic composition and comparison with those of algal lipids.