Markus Fischer

• Prof. Dr.
• Head Department of Chemistry, Director Hamburg School of Food Science at Hamburg University

DNA microarrays are now used in fields such as gene expression analysis, pathogen/virus detection and identification of biomarkers. Although they have been used in the food sector for species identification, they detect a limited number of species and are thus less suited for fishery products due to the large variety of traded species. Here, the ai...

Fluorine-containing flavin derivatives can be used as probes in flavin-binding proteins forming radical pairs to exploit the photo-chemically induced dynamic nuclear polarization (photo-CIDNP) effect. Knowledge of the hyperfine structure is crucial for studying the mechanism of intramolecular radical-pair formation in proteins. Transient ¹⁹F photo-...

Riboflavin analogs lacking one methyl group (7α or 8α) can still serve as a surrogate for riboflavin in riboflavin-deficient microorganisms or animals. The absence of both methyl groups at once completely abolishes this substitution capability. To elucidate the molecular mechanisms behind this phenomenon, we performed an adaptive laboratory evoluti...

The application and development of fast and simple screening methods for the authentication of foods has increased continuously in recent years. A widely used analytical technique is Fourier transform near-infrared...

Featured Application The Authors demonstrate the preparation and application of LAMP-based mobile testing at the point of care for authentication of animal and plant derived food. Abstract The potential of loop-mediated isothermal amplification (LAMP) assays for species identification in medical diagnostics, food safety, and authentication is indi...

Apples are among the most important fruits worldwide and the most consumed fruit in Germany. Due to higher energy and personnel costs, domestic apples are more expensive and thus offer an incentive for mixing with foreign goods. Moreover, imported apples have a higher carbon footprint, which is an obstacle regarding sales in times of climate change...

The LOV2 domain from Avena sativa ( As ) is a blue light receptor that undergoes adduct formation with the native flavin mononucleotide (FMN) cofactor [Salomon et al ., Biochemistry , 2000, 39 , 9401]....

The methyl-d-erythritol phosphate (MEP) pathway has emerged as an interesting target in the fight against antimicrobial resistance. The pathway is essential in many human pathogens, including Plasmodium falciparum (Pf), but is absent in human cells. In the present study, we report on the discovery of a new chemical class targeting IspD, the third e...

Element profiling is a powerful tool for detecting fraud related to claims of geographical origin. However, these methods must be continuously developed, as mixtures of different origins in particular offer great potential for adulteration. This study is a proof of principle to determine whether elemental profiling is suitable for detecting mixture...

Studying the metabolic role of non‐essential promiscuous enzymes is a challenging task, as genetic manipulations usually do not reveal at which point(s) of the metabolic network the enzymatic activity of such protein is beneficial for the organism. Each of the HAD‐like phosphatases YcsE, YitU and YwtE of Bacillus subtilis catalyzes the dephosphoryl...

The Mediterranean herb oregano is one of the most frequently adulterated foods. Often morphologically similar leaf material is used as a filler, which can generally be detected using DNA-based methods. Loop-mediated isothermal amplification (LAMP) has high potential for point-of-care testing as it requires only a simple device for sample incubation...

The methyl-D-erythritol phosphate (MEP) pathway has emerged as an interesting target in the fight against antimicrobial resistance. The pathway is essential in many human pathogens, including Plasmodium falciparum (Pf), but is absent in human cells, reducing the risk of off-target side effects. In the present study, we conducted a high-throughput s...

Die Authentizitätsprüfungen von Lebensmitteln und deren Rohstoffen ist in der amtlichen Lebensmittelüberwachung schon seit einiger Zeit ein großes Themenfeld – es geht um die Aspekte Lebensmitteltäuschung und Lebensmittelsicherheit. Eine effiziente und kostengünstige Untersuchungsmethode stellt das DNA‐basierte Next Generation Sequencing (NGS) dar,...

The blue-light photoreceptor YtvA from Bacillus subtilis has an N-terminal flavin mononucleotide (FMN)-binding light-oxygen-voltage (LOV) domain that is fused to a C-terminal sulfate transporter and anti-σ factor antagonist (STAS) output domain. To interrogate the signal transduction pathway that leads to photoactivation, the STAS domain was replac...

The detection of raw material defects, e.g., due to incorrect or excessively long storage, is an important issue in incoming goods inspections in the food industry. Fast and easy-to-use analytical methods for evaluating the usability of raw materials are particularly important. In this study, the applicability of Fourier transform near-infrared (FT...

High complex stability and longitudinal relaxivity of Gd‐based contrast agents are important requirements for magnetic resonance imaging (MRI) because they ensure patient safety and contribute to measurement sensitivity. Charged and zwitterionic Gd³⁺‐complexes of the well‐known chelator 1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetraacetic acid (DOTA...

5-Deazaflavins are analogs of naturally occurring flavin cofactors. They serve as substitutes for natural flavin cofactors to investigate and modify the reaction pathways of flavoproteins. Demethylated 5-deazaflavins are potential candidates for artificial cofactors, allowing us to fine-tune the reaction kinetics and absorption characteristics of f...

The price of different truffle types varies according to their culinary value, sometimes by more than a factor of 10. Nonprofessionals can hardly distinguish visually the species within the white or black truffles, making the possibility of food fraud very easy. Therefore, the identification of different truffle species (Tuber spp.) is an analytica...

The untargeted metabolomics analysis of biological samples with nuclear magnetic resonance (NMR) provides highly complex data containing various signals from different molecules. To use these data for classification, e.g., in the context of food authentication, machine learning methods are used. These methods are usually applied as a black box, whi...

Discovery of novel antibiotics needs multidisciplinary approaches to gain target enzyme and bacterial activities while aiming for selectivity over mammalian cells. Here, we report a multiparameter optimisation of a fragment‐like hit that was identified through a structure‐based virtual‐screening campaign on Escherichia coli IspE crystal structure....

Accelerated storage is routinely used with pharmaceuticals to predict stability and degradation patterns over time. The aim of this is to assess the shelf life and quality under harsher conditions, providing crucial insights into their long-term stability and potential storage issues. This study explores the potential of transferring this approach...

The price of different truffle types varies according to their culinary value, sometimes by more than a factor of ten. Non-professionals can hardly distinguish the species within the white or black truffles by eye, which makes the possibility of food fraud very easy. Therefore, the identification of different truffle species (Tuber spp.) is an anal...

Deazaflavins are important analogues of the naturally occurring flavins: riboflavin, flavin mononucleotide (FMN), and flavin adenine dinucleotide (FAD). The use of 5‐deazaflavin as a replacement coenzyme in a number of flavoproteins has proven particularly valuable in unraveling and manipulating their reaction mechanisms. It was frequently reported...

Deazaflavins are important analogues of the naturally occurring flavins: riboflavin, flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD). The use of 5‐deazaflavin as replacement coenzyme in a number of flavoproteins has proven particularly valuable in unraveling and manipulating their reaction mechanisms. It was frequently reported th...

Nutmeg is a popular spice often used in ground form, which makes it highly susceptible to food fraud. Therefore, the aim of the present study was to detect adulteration of ground nutmeg with nutmeg shell via Fourier transform near-infrared (FT-NIR) spectroscopy. For this purpose, 36 authentic nutmeg samples and 10 nutmeg shell samples were analyzed...

The importance of animal welfare and the organic production of chicken eggs has increased in the European Union in recent years. Legal regulation for organic husbandry makes the production of organic chicken eggs more expensive compared to conventional husbandry and thus increases the risk of food fraud. Therefore, the aim of this study was to deve...

This review explains the strategies behind genomics, proteomics, metabolomics, metallomics and isotopolomics approaches and their applicability to written artefacts. The respective sub-chapters give an insight into the analytical procedure and the conclusions drawn from such analyses. A distinction is made between information that can be obtained f...

Unlabelled: To prevent food fraud, products can be monitored by various chemical-analytical techniques. In this study, we present a CRISPR-Cpf1 DETECTR-based assay for the differentiation of plant ingredients in sweet confectionary like fine and bulk-cocoa, or bitter and sweet almonds. To enable rapid in-field analysis, the trans-cleavage activity...

Oregano (Origanum vulgare and O. onites) is one of the most frequently counterfeited herbs in the world and is diluted with the leaves of a wide variety of plants. In addition to olive leaves, marjoram (O. majorana) is often used for this purpose in order to achieve a higher profit. However, apart from arbutin, no marker metabolites are known to re...

Lipids make up more than half of the human brain's dry weight, yet the composition and function of the brain lipidome is not well characterized. They not only provide the structural basis of cell membranes, but also take part in a wide variety of biochemical processes. In neurodegenerative diseases, lipids can facilitate neuroprotection and serve a...

Aptamers offer several advantages over antibodies. However, to ensure high affinity and specificity, a better understanding of the interactions between the nucleic-acid-based aptamers and their targets is mandatory. Therefore, we investigated the influence of two physical properties of proteins—molecular mass and charge—on the affinity of nucleic-a...

Top-down proteomics deals with the characterization of intact biomolecules, which reduces the sample complexity and facilitates the detection of modifications at the protein level. The combination of the matrix-assisted laser desorption/ionization (MALDI) technique with time-of-flight (TOF) mass analysis allows for the generation of gaseous ions in...

The determination of the cocoa shell content is of interest because a high shell content causes a reduction in the quality of cocoa products. Consequently, the aim of the present study was the development of a routinely applicable method for the quantitation of shell material in cocoa nibs. For this, 51 fermented cocoa samples of different varietie...

Storage is a critical step in the post-harvest processing of hazelnuts, as it can lead to mold, rancidity, and off-flavor. However, there is a lack of analytical methods to detect improper or extended storage. To comprehensively investigate the effects of hazelnut storage, samples were stored under five different conditions for up to 18 months. Sub...

To address the continued rise of multi-drug-resistant microorganisms, the development of novel drugs with new modes of action is urgently required. While humans biosynthesize the essential isoprenoid precursors isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP) via the established mevalonate pathway, pathogenic protozoa and certain...

The analytical requirements for food testing have increased significantly in recent years. On the one hand, because food fraud is becoming an ever‐greater challenge worldwide, and on the other hand because food safety is often difficult to monitor due to the far‐reaching trade chains. In addition, the expectations of consumers on the quality of foo...

In the present manuscript, we describe how we successfully used ligand-based virtual screening (LBVS) to identify two small-molecule, drug-like hit classes with excellent ADMET profiles against the difficult to address microbial enzyme 1-deoxy-d-xylulose-5-phosphate synthase (DXPS). In the fight against antimicrobial resistance (AMR), it has become...

Storage is a critical step in post-harvest processing of hazelnuts since it can lead to mold, rancidity and off-flavor. To comprehensively investigate the effects of hazelnut storage, samples were stored under three short-term and two long-term conditions and the polar metabolome was analyzed by 1H NMR spectroscopy at different time points. Large d...

Cocoa cultivation is dominated by the clone "Colleción Castro Naranjal 51" (CCN-51). In contrast, CCN-51 is the expensive and aromatic fine cocoa "Arriba Nacional" from Ecuador. The differences in the overall quality of the beans and in the prices show that it is necessary to develop a rapid and accurate method to distinguish these varieties and pr...

Near-infrared (NIR) spectroscopy is a proven tool for the determination of food authenticity, mainly because of good classification results and the possibility of industrial use due to its easy and fast application. Since water shows broad absorption bands, the water content of a sample should be as low as possible. Freeze-drying is a commonly used...