Unser 10. Leibniz Plant Biochemistry Symposium am 7. und 8. Mai war ein großer Erfolg. Thematisch ging es in diesem Jahr um neue Methoden und Forschungsansätze der Naturstoffchemie. Die exzellenten Vorträge über Wirkstoffe…
Omanische Heilpflanze im Fokus der Phytochemie IPB-Wissenschaftler und Partner aus Dhofar haben jüngst die omanische Heilpflanze Terminalia dhofarica unter die phytochemische Lupe genommen. Die Pflanze ist reich an…
Geschmack ist vorhersagbar: Mit FlavorMiner. FlavorMiner heißt das Tool, das IPB-Chemiker und Partner aus Kolumbien jüngst entwickelt haben. Das Programm kann, basierend auf maschinellem Lernen (KI), anhand der…
Vasco, A. V.; Moya, C. G.; Gröger, S.; Brandt, W.; Balbach, J.; Pérez, C. S.; Wessjohann, L. A.; Rivera, D. G.;Insights into the secondary structures of lactam N-substituted stapled peptidesOrg. Biomol. Chem.183838-3842(2020)DOI: 10.1039/D0OB00767F
Stapled peptides derived from the Ugi macrocyclization comprise a special class of cyclopeptides with an N-substituted lactam bridge cross-linking two amino acid side chains. Herein we report a comprehensive analysis of the structural factors influencing the secondary structure of these cyclic peptides in solution. Novel insights into the s-cis/s-trans isomerism and the effect of N-functionalization on the conformation are revealed.
Publikation
Hussain, H.; Ziegler, J.; Hause, G.; Wohlrab, J.; Neubert, R. H.;Quantitative Analysis of Free Amino Acids and Urea Derived from Isolated Corneocytes of Healthy Young, Healthy Aged, and Diseased SkinSkin Pharmacol. Physiol.3294-100(2019)DOI: 10.1159/000495992
Background/Aims: Free amino acids (FAAs) and urea, present inside the corneocytes, can be important indicators of skin condition. However, due to the lack of a standard extraction protocol for FAAs from corneocytes, conflicting research results have been reported. Therefore, the purpose of this study was (1) to standardize the extraction protocol and (2) to investigate FAA profiles in healthy young and healthy old volunteers, as well as in psoriasis and atopic dermatitis patients. Methods: Skin samples were collected from four groups (healthy young, healthy old, and psoriasis and atopic dermatitis patients) with 5 volunteers per group. Corneocytes were isolated and examined microscopically. FAAs and urea were extracted from the isolated corneocytes, and their amounts were quantified using LC-ESI/MS/MS (after derivatization with Fmoc-Cl) and colorimetric methods, respectively. Results: The micrographs of the corneocytes showed no morphological features attributable to age or disease conditions. The highest and lowest concentrations of total FAAs and urea were observed in the healthy old group and the healthy young group, respectively. Unlike the other FAAs and urea, citrulline was found at a higher level in the healthy young group than in the disease groups. Conclusion: This study suggests that the levels of FAAs and urea in the skin are affected by age and skin conditions (healthy/diseased). However, further studies are needed to show the effects of different skin conditions on the levels of FAAs and urea.
Publikation
Vattekkatte, A.; Garms, S.; Brandt, W.; Boland, W.;Enhanced structural diversity in terpenoid biosynthesis: enzymes, substrates and cofactorsOrg. Biomol. Chem.16348-362(2018)DOI: 10.1039/C7OB02040F
The enormous diversity of terpenes found in nature is generated by enzymes known as terpene synthases, or cyclases. Some are also known for their ability to convert a single substrate into multiple products. This review comprises monoterpene and sesquiterpene synthases that are multiproduct in nature along with the regulation factors that can alter the product specificity of multiproduct terpene synthases without genetic mutations. Variations in specific assay conditions with focus on shifts in product specificity based on change in metal cofactors, assay pH and substrate geometry are described. Alterations in these simple cellular conditions provide the organism with enhanced chemodiversity without investing into new enzymatic architecture. This versatility to modulate product diversity grants organisms, especially immobile ones like plants with access to an enhanced defensive repertoire by simply altering cofactors, pH level and substrate geometry.
Publikation
Bürstenbinder, K.; Mitra, D.; Quegwer, J.;Functions of IQD proteins as hubs in cellular calcium and auxin signaling: A toolbox for shape formation and tissue-specification in plants?Plant Signal Behav.12e1331198(2017)DOI: 10.1080/15592324.2017.1331198
Calcium (Ca2+) ions play pivotal roles as second messengers in intracellular signal transduction, and coordinate many biological processes. Changes in intracellular Ca2+ levels are perceived by Ca2+ sensors such as calmodulin (CaM) and CaM-like (CML) proteins, which transduce Ca2+ signals into cellular responses by regulation of diverse target proteins. Insights into molecular functions of CaM targets are thus essential to understand the molecular and cellular basis of Ca2+ signaling. During the last decade, IQ67-domain (IQD) proteins emerged as the largest class of CaM targets in plants with mostly unknown functions. In the March issue of Plant Physiology, we presented the first comprehensive characterization of the 33-membered IQD family in Arabidopsis thaliana. We showed, by analysis of the subcellular localization of translational green fluorescent protein (GFP) fusion proteins, that most IQD members label microtubules (MTs), and additionally often localize to the cell nucleus or to membranes, where they recruit CaM Ca2+ sensors. Important functions at MTs are supported by altered MT organization and plant growth in IQD gain-of-function lines. Because IQD proteins share structural hallmarks of scaffold proteins, we propose roles of IQDs in the assembly of macromolecular complexes to orchestrate Ca2+ CaM signaling from membranes to the nucleus. Interestingly, expression of several IQDs is regulated by auxin, which suggests functions of IQDs as hubs in cellular auxin and calcium signaling to regulate plant growth and development.