Laure Guilhaudis

Université de Rouen | UR · UFR Sciences et Techniques

The amphibian family Leptodactylidae is divided into three sub-families: Leiuperinae, Leptodactylinae, and Paratelmatobiinae. Host-defense peptides (HDPs) present in the skins of frogs belonging to the Leptodactylinae have been studied extensively, but information is limited regarding peptides from Leiuperinae species. Peptidomic analysis of norepi...

Frogs from the extensive amphibian family Hylidae are a rich source of peptides with therapeutic potential. Peptidomic analysis of norepinephrine-stimulated skin secretions from the Giant Gladiator Treefrog Boana boans (Hylidae: Hylinae) collected in Trinidad led to the isolation and structural characterization of five host-defense peptides with li...

Large amounts of root exudates are released by plant roots into the soil. Due to their importance in regulating the rhizosphere properties, it is necessary to unravel the precise composition and function of exudates at the root-soil interface. However, obtaining root exudates without inducing artefacts is a difficult task. To analyse the low molecu...

The SorLA protein, encoded by the SORL1 gene, is a major player in Alzheimer’s disease (AD) pathophysiology. Functional and genetic studies demonstrated that SorLA deficiency results in increased production of Aβ peptides, and thus a higher risk of AD. A large number of SORL1 missense variants have been identified in AD patients, but their function...

The aging of our population is accompanied by an increased prevalence of chronic diseases. Among those, liver, joint and adipose tissue-related pathologies have a major socio-economic impact. They share common origins as they result from a dysregulation of the inflammatory and metabolic status. Plant-derived nutrients and especially polyphenols, ex...

The SorLA protein, encoded by the SORL1 gene, is a major player in Alzheimer disease (AD) pathophysiology. Functional and genetic studies demonstrated that SorLA deficiency results in increased production of Aβ peptides, and thus a higher risk of AD. A large number of SORL1 missense variants have been identified in AD patients, but their functional...

The aim of the study was to determine the in vitro immunomodulatory, cytotoxic, and insulin‐releasing activities of seven phylloseptin‐TR peptides and plasticin‐TR, first isolated from the frog Phyllomedusa trinitatis. The most cationic peptides, phylloseptin‐1.1TR and phylloseptin‐3.1TR, showed greatest cytotoxic potency against A549, MDA‐MB231, a...

Electronic circular dichroism is one of the most used spectroscopic techniques for peptide and protein structural characterization. However, while valuable experimental spectra exist for α-helix, β-sheet and random coil secondary structures, previous studies showed important discrepancies for β-turns, limiting their use as a reference for structura...

Of four naturally occurring frenatin peptides tested, frenatin 2D (DLLGTLGNLPLPFI.NH2) from Discoglossus sardus was the most potent and effective in producing concentration-dependent stimulation of insulin release from BRIN-BD11 rat clonal β-cells without displaying cytotoxicity. The peptide also stimulated insulin release from 1.1B4 human-derived...

Cholesterol is doubtless one of the most studied bio-molecules, which unfortunately features low emitting properties, precluding its in vivo study by fluorescence experiments. The design of fluorescent analogues of cholesterol is thus an appealing challenge in biochemistry, which simultaneously requires minor changes in its chemical structure (to r...

The Mexican burrowing toad Rhinophrynus dorsalis is the sole extant representative of the Rhinophrynidae. United in the superfamily Pipoidea, the Rhinophrynidae is considered to be the sister-group to the extant Pipidae which comprises Hymenochirus, Pipa, Pseudhymenochirus and Xenopus. Cationic, α-helical host-defense peptides of the type found in...

We have recently characterized bicarinalin as the most abundant peptide from the venom of the ant Tetramorium bicarinatum. This antimicrobial peptide is active against Staphylococcus and Enterobacteriaceae. To further investigate the antimicrobial properties of this cationic and cysteine-free peptide, we have studied its antibacterial, antifungal a...

Isotopic labeling is widely used in various fields like proteomics, metabolomics, fluxomics, as well as in NMR structural studies, but it requires an efficient determination of the isotopic enrichment. Mass spectrometry is the method of choice for such analysis. However, when complex systems like hairy roots are used for production, multiple popula...

Background and purpose: The neuropeptide 26RFa and its cognate receptor GPR103 are involved in the control of food intake and bone mineralization. Here, we have tested, experimentally, the predicted ligand-receptor interactions by site-directed mutagenesis of GPR103 and designed point-substituted 26RFa analogues. Experimental approach: Using the...

This unique book covers fundamentals of organolithium compounds and gives a comprehensive overview of the latest synthetic advances and developments in the field. Part I covers computational and spectroscopic aspects as well as structure-reactivity relationships of organolithiums, whereas Part II deals with new lithium-based synthetic methodologies...

A series of four fluorinated dipeptide analogues each containing a fluoro-olefin moiety as peptide bond surrogate has been designed and synthesized. These motifs have been successfully introduced into the bioactive C-terminal heptapeptide of the neuropeptide 26RFa by conventional SPPS. We then evaluated the ability of the generated pseudopeptides t...

26RFa, a novel RFamide neuropeptide, is the endogenous ligand of the former orphan receptor GPR103. Intracerebroventricular injection of 26RFa and its C-terminal heptapeptide, 26RFa((20-26)), stimulates food intake in rodents. To develop potent, stable ligands of GPR103 with low molecular weight, we have designed a series of aza-β(3)-containing 26R...

Brevinin-1BYa (FLPILASLAAKFGPKLFCLVTKKC), first isolated from skin secretions of the frog Rana boylii, displays broad-spectrum antimicrobial activity and potent haemolytic activity. This study investigates the effects on conformation and biological activity of replacement of the intramolecular disulphide bridge in the peptide by a non-reducible dic...

PAC1 receptor is abundant in the CNS and plays an important role in neuronal survival. To identify the molecular determinants and the conformational components responsible for the activation of the PAC1 receptor, we performed a SAR study focusing on the N-terminal domain of its endogenous ligand, PACAP. This approach revealed that residues Asp(3) a...

Kisspeptins, the natural ligands of the G protein-coupled receptor KISS1R, comprise a family of related peptides derived from the proteolytic processing of a common precursor encoded by the KISS1 gene. Among those, Kisspeptin-10 (Kp-10) contains the basic residues to retain full functional activity and exhibits higher receptor affinity and biopoten...

Spondias purpurea L. (Anacardiaceae), disseminated in Venezuela, produces a polysaccharide gum constituted by galactose (59%), arabinose (9%), mannose (2%), xylose (2%), rhamnose (2%) and uronic acids (26%). It also contains a proteinaceous material (2%). The original gum was subjected to two successive Smith-degradation process to obtain polysacch...

The affinity toward the PAC1 receptor, the biological activity, and the alpha-helical content of several truncated PACAP27 analogs were measured. We first evaluated the pharmacological and structural parameters of C-terminal shortened PACAP fragments, from PACAP(1-23) to PACAP(1-19). All carboxy-truncated derivatives demonstrated circular dichroism...

Urotensin-II (U-II) is a vasoactive hormone that acts through a G-protein-coupled receptor named UT. Recently, we have shown, using the surface plasmon resonance technology that human U-II (hU-II) interacts with the hUT(281-300) fragment, a segment containing the extracellular loop III (EC-III) and short extensions of the transmembrane domains VI a...

Urotensin II (U-II) and urotensin II-related peptide (URP) are the endogenous ligands for the orphan G-protein-coupled receptor GPR14 now renamed UT. At the periphery, U-II and/or URP exert a wide range of biological effects on cardiovascular tissues, airway smooth muscles, kidney and endocrine glands, while central administration of U-II elicits v...

Human KIN17 is a 45-kDa eukaryotic DNA- and RNA-binding protein that plays an important role in nuclear metabolism and in particular in the general response to genotoxics. Its amino acids sequence contains a zinc finger motif (residues 28-50) within a 30-kDa N-terminal region conserved from yeast to human, and a 15-kDa C-terminal tandem of SH3-like...

Urotensin-II (U-II) and urotensin-II-related peptide (URP) are potent vasoconstrictors, and this action is mediated through a G protein-coupled receptor identified as UT. This receptor is expressed abundantly in the mammalian cardiovasculature, and the effects of U-II and URP can be blocked with urantide, a selective antagonist. Thus, we carried ou...

A number of RFamide peptides have been characterized in invertebrate species and these peptides have been found to exert a broad spectrum of biological activities. In contrast, in vertebrates, our knowledge on RFamide peptides is far more limited and only a few members of the RFamide peptide family have been identified in various vertebrate classes...

A novel hypothalamic neuropeptide of the RFamide family, comprising 26 amino acids residues and thus termed 26RFa, has been recently characterized in human, and was found to be the endogenous ligand for the orphan G protein-coupled receptor GPR103. Intracerebroventricular injection of 26RFa provokes a robust increase in food intake in rodents. In t...

Urotensin II (UII) has been described as the most potent vasoconstrictor peptide and recognized as the endogenous ligand of the orphan G protein-coupled receptor GPR14. Recently, a UII-related peptide (URP) has been isolated from the rat brain and its sequence has been established as H-Ala-Cys-Phe-Trp-Lys-Tyr-Cys-Val-OH. In order to study the struc...

In HIV the viral envelope protein is processed by a host cell protease to form gp120 and gp41. The C1 and C5 domains of gp120 are thought to directly interact with gp41 but are largely missing from the available X-ray structure. Biophysical studies of the HIV gp120 C5 domain (residues 489-511 of HIV-1 strain HXB2), which corresponds to the carboxy...

Chloroplast thioredoxin m from the green alga Chlamydomomas reinhardtii is very efficiently reduced in vitro and in vivo in the presence of photoreduced ferredoxin and a ferredoxin dependent ferredoxin-thioredoxin reductase. Once reduced, thioredoxin m has the capability to quickly activate the NADP malate dehydrogenase (EC 1.1.1.82) a regulatory e...

Chloroplast thioredoxin m from the green alga Chlamydomomas reinhardtii is very efficiently reduced in vitro and in vivo in the presence of photoreduced ferredoxin and a ferredoxin dependent ferredoxin-thioredoxin reductase. Once reduced, thioredoxin m has the capability to quickly activate the NADP malate dehydrogenase (EC 1.1.1.82) a regulatory e...

The lipoate containing H-protein plays a pivotal role in the catalytic cycle of the glycine decarboxylase complex (GDC), undergoing reducing methylamination, methylene transfer, and oxidation. The transfer of the CH(2) group is catalyzed by the T-protein, which forms a 1:1 complex with the methylamine-loaded H-protein (Hmet). The methylamine group...

The lipoate-dependent H protein plays a pivotal role in the catalytic cycle of the glycine decarboxylase complex (GDC), undergoing reducing methylamination, methylene transfer, and oxidation. The local structure and backbone dynamics of the methylamine-loaded H (Hmet), oxidized H (Hox), and H apoprotein (Hapo) have been investigated in solution. Fi...

Spondias mombin gum is constituted by a carbohydrate main fraction and an important protein component (20.65%). An exhaustive study of the carbohydrate-protein interaction in Spondias mombin gum, using Size Exclusion Chromatograpy (SEC) and Nuclear Magnetic Resonance (NMR), was the objective of this investigation. The original gum was submitted t...