Petros Giastas

Insulin-Regulated Aminopeptidase (IRAP) is an enzyme with important biological functions and the target of several drug-discovery efforts although no clinically useful inhibitors have been reported yet. We combined in silico screening with a medicinal chemistry optimization campaign to discover a nanomolar inhibitor of IRAP based on a pyrazolylpyri...

Background: Hypertension worsens outcomes in SARS-CoV-2 patients. Sartans, a type of antihypertensive angiotensin receptor blocker-(ARB), reduce COVID-19 morbidity and mortality by targeting angiotensin-converting enzyme-2 (ACE2). This study aimed to evaluate the antiviral and antihypertensive effects of nirmatrelvir, commercial sartans (candesart...

Objectives ER aminopeptidase 1 (ERAP1) in an intracellular enzyme that optimizes the peptide cargo of Major Histocompatibility Class I molecules (MHC-I) and regulates adaptive immune responses thus being an emerging target for immunotherapy applications. It has unusual substrate selectivity, preferring longer peptides to shorter ones and its trimmi...

[This corrects the article DOI: 10.3389/fphar.2019.00474.].

Endoplasmic reticulum aminopeptidase 2 (ERAP2) is a key enzyme involved in the trimming of antigenic peptides presented by Major Histocompatibility Complex class I. It is a target of growing interest for the treatment of autoimmune diseases and in cancer immunotherapy. However, the discovery of potent and selective ERAP2 inhibitors is highly challe...

Endoplasmic reticulum aminopeptidase 2 (ERAP2) is a key enzyme involved in the trimming of antigenic peptides presented by Major Histocompatibility Complex class I. It is a target of growing interest for the treatment of autoimmune diseases and in cancer immunotherapy. However, the discovery of potent and selective ERAP2 inhibitors is highly challe...

The β3 subunit of nicotinic acetylcholine receptors (nAChRs) participates in heteropentameric assemblies with some α and other β neuronal subunits forming a plethora of various subtypes, differing in their electrophysiological and pharmacological properties. While β3 has for several years been considered an accessory subunit without direct particip...

The oxytocinase subfamily of M1 zinc aminopeptidases comprises emerging drug targets, including the ER-resident aminopeptidases 1 and 2 (ERAP1 and ERAP2) and insulin-regulated aminopeptidase (IRAP); however, reports on clinically relevant inhibitors are limited. Here we report a new synthetic approach of high diastereo- and regioselectivity for fun...

Insulin-regulated aminopeptidase (IRAP) is a transmembrane zinc metallopeptidase with many important biological functions and an emerging pharmacological target. Although previous structural studies have given insight on how IRAP recognizes linear peptides, how it recognizes its physiological cyclic ligands remains elusive. Here, we report the firs...

The high-resolution X-ray crystal structures of the adducts formed between the “half sandwich”-type Ru(II) coordination compound [RuII(1,4,7-trithiacyclononane)(ethane-1,2-diamine)Cl]+ and two proteins, namely hen egg-white lysozyme and proteinase K, are presented. The structures unveil that upon reaction with both enzymes the Ru(II) compound is co...

Endoplasmic reticulum aminopeptidase 1 (ERAP1) is an intracellular enzyme that optimizes the peptide cargo of major histocompatibility class I (MHC-I) molecules and regulates adaptive immunity. It has unusual substrate selectivity for length and sequence, resulting in poorly understood effects on the cellular immunopeptidome. To understand substrat...

The α9 subunit of nicotinic acetylcholine receptors (nAChRs) exists mainly in heteropentameric assemblies with α10. Accumulating data indicate the presence of three different binding sites in α9α10 nAChRs: the α9(+)/α9(-), the α9(+)/α10(-), and the α10(+)/α9(-). The major role of the principal (+) side of the extracellular domain (ECD) of α9 subuni...

Ba0331 is a putative polysaccharide deacetylase from Bacillus anthracis, the etiological agent of the disease anthrax, that contributes to adaptation of the bacterium under extreme conditions and to maintenance of the cell shape. In the present study, the crystal structure of Ba0331 was determined at 2.6 Å resolution. The structure consists of two...

ER aminopeptidase 1 (ERAP1) is an intracellular enzyme that helps generate peptides presented by MHC class I molecules and is an emerging target for immunotherapy applications. Despite almost two decades of research on ERAP1, lack of high-resolution crystal structures has hampered drug-development efforts. By optimizing the protein construct, we ob...

Functional and folding constraints impose interdependence between interacting sites along the protein chain that are envisaged through protein sequence evolution. Studying the influence of structure in phylogenetic models requires detailed and reliable structural models. Polysaccharide deacetylases (PDAs), members of the carbohydrate esterase famil...

The cell wall peptidoglycan is recognized as a primary target of the innate immune system and usually its disintegration results in bacterial lysis. Bacillus cereus, a close relative of the highly virulent Bacillus anthracis, contains 10 polysaccharide deacetylases. Among these, the peptidoglycan N-acetylglucosamine deacetylase Bc1974 is the highes...

The enantioselectivity of β-cyclodextrin (β-CD) towards L- and D-N-acetyltryptophan (NAcTrp) has been studied in aqueous solution and the crystalline state. NMR studies in solution show that β-CD forms complexes of very similar but not identical geometry with both L- and D-NAcTrp and exhibits stronger binding with L-NAcTrp. In the crystalline state...

Experimental data containing geometry data of the β-CD hosts; H-bonding interactions in the β-CD dimer; NMR data (Job plots and 2D maps of the observed dipolar interactions); packing, origin selection and comparison of monomeric β-CD complexes; modeling results of D-NAcTrp/β-CD.

Nicotinic ACh receptors (nAChRs) are the best studied members of the superfamily of pentameric ligand-gated ion channels (pLGICs). Neuronal nAChRs regulate neuronal excitability and neurotransmitter release in the nervous system and form either homo- or hetero-pentameric complexes with various combinations of the 11 neuronal nAChR subunits (α2-7, α...

Insulin-regulated aminopeptidase (IRAP) is an enzyme with several important biological functions that is known to process a large variety of different peptidic substrates although the mechanism behind this wide specificity is not clearly understood. We describe a crystal structure of IRAP in complex with a recently developed bioactive and selective...

Endoplasmic reticulum aminopeptidase 2 assists with the generation of antigenic peptides for presentation onto Major Histocompatibility Class I molecules in humans. Recent evidence has suggested that the activity of ERAP2 may contribute to the generation of autoimmunity, thus making ERAP2 a possible pharmacological target for the regulation of adap...

Significance Nicotinic acetylcholine receptors (nAChRs) are pentameric ligand-gated ion channels involved in fast neurotransmission. Here, we present the crystal structure of the homopentameric assembly of the extracellular domain (ECD) of α2 nAChR subunit in complex with an agonist. The structure provides a unique opportunity to probe the interact...

We present here the self-assembling of a green - emitting metallosupramolecular romboid into a rigid, highly – ordered 3D multichromophoric network through the mediation of a tetra-anionic violet – blue molecular emitter. Control was obtained on the spatial topology, the electronic energy landscape and the fluorescence polarization of the interacti...

Endoplasmic reticulum aminopeptidases process antigenic peptide precursors to generate epitopes for presentation by MHC class I molecules and help shape the antigenic peptide repertoire and cytotoxic T-cell responses. To perform this function, ER aminopeptidases have to recognize and process a vast variety of peptide sequences. To understand how th...

p>The α9α10 nicotinic acetylcholine receptor (nAChR) was first identified in the auditory system, where it mediates synaptic transmission between efferent olivocochlear cholinergic fibers and cochlea hair cells. This receptor gained further attention due to its potential role in chronic pain and breast and lung cancers. We previously showed that α-...

Membrane-anchored lipoproteins have a broad range of functions and play key roles in several cellular processes in Gram-positive bacteria. BA0330 and BA0331 are the only lipoproteins among the 11 known or putative polysaccharide deacetylases of Bacillus anthacis. We found that both lipoproteins exhibit unique characteristics. BA0330 and BA0331 inte...

The α9α10 nicotinic acetylcholine receptor (nAChR) was first identified in the auditory system, where it mediates synaptic transmission between efferent olivocochlear cholinergic fibers and cochlea hair cells. This receptor gained further attention due to its potential role in chronic pain and breast and lung cancers. We previously showed that α-co...

We determined the X-ray crystal structures of the extracellular domain (ECD) of the monomeric state of human neuronal α9 nicotinic acetylcholine receptor (nAChR) and of its complexes with the antagonists methyllycaconitine and α-bungarotoxin at resolutions of 1.8 Å, 1.7 Å and 2.7 Å, respectively. The structure of the monomeric α9 ECD superimposed w...

The effect of non-contact current transfer on the crystallization of three model proteins (hen egg white lysozyme, bovine pancreatic ribonuclease A, and human recombinant insulin) was investigated using a prototype ion-generator device. The device can produce an equivalent of microcurrent that can be transmitted in a contactless manner by spraying...

The muscle nicotinic acetylcholine receptor (AChR) has a central role in neuromuscular transmission, and is the major target in the autoimmune disease myasthenia gravis (MG). We created mutants of the extracellular domains (ECD) of the human α1, β1, δ and ɛ AChR subunits, whereby their Cys-loop was exchanged for that of the acetylcholine binding pr...

The synthesis and spectroscopic characterization of [Rh{R2P(S)NP(S)R2-S,S′}(cod)] [cod = 1,5-cyclooctadiene; R = Ph (1), iPr (4)], [Rh{Ph2P(S)NP(S)Ph2-S,S′}(CO)2] (2) and [Rh{Ph2P(S)NP(S)Ph2-S,S′}(CO)(PPh3)] (3) is described. The crystal structures of complexes 1 and 3 are also presented. The synthesized RhI complexes are essentially not catalytica...

Endoplasmic reticulum aminopeptidases 1 and 2 (ERAP1 and ERAP2) cooperate to trim antigenic peptide precursors for loading onto MHC class I molecules and help regulate the adaptive immune response. Common coding single nucleotide polymorphisms in ERAP1 and ERAP2 have been linked with predisposition to human diseases ranging from viral and bacterial...

Structural genomics or structural proteomics can be defined as the quest to obtain the three-dimensional structures of all proteins. Single-crystal X-ray crystallography provides the most direct, accurate and in most of the cases the only way of forming images of macromolecules. Using crystallography, three-dimensional images have been made of thou...

The crystal structures of the C57A and V13G molecular variants of Allochromatium vinosum 2[4Fe-4S] ferredoxin (AlvinFd) and that of the homologous ferredoxin from Escherichia coli (EcFd) have been determined at 1.05-, 1.48-, and 1.65-A resolution, respectively. The present structures combined with cyclic voltammetry studies establish clear effects...

Octakis(6-bromo-6-deoxy)cyclomaltooctaose, perbrominated gamma-cyclodextrin at the primary side, crystallises from methanol in a very unique manner. The macrocycles are quite distorted in contrast to their beta-cyclodextrin analogue, heptakis(6-bromo-6-deoxy)cyclomaltoheptaose. The two monomers, arranged head-to-head, form a completely new kind of...

The structure of the 2[4Fe-4S] ferredoxin (PaFd) from Pseudomonas aeruginosa, which belongs to the Allochromatium vinosum (Alvin) subfamily, has been determined by X-ray crystallography at 1.32-A resolution, which is the highest up to now for a member of this subfamily of Fds. The main structural features of PaFd are similar to those of AlvinFd. Ho...

As a part of a systematic investigation of the inclusion compounds of plant growth regulators in Cyclodextrins (CDs) we report here the crystal structures of the complexes of 4-chlorophenoxyacetic acid (4CPA) encapsulated in -CD (4CPA/-CD) and in heptakis(2,3,6-tri-O-methyl)--CD (4CPA/TMCD). 4CPA is considered as a sufficiently safe plant growth re...

(Chemical Equation Presented) Sowing the seeds: Complexation of rac-1 in the solid state with a guest such as Et2O in the gas phase proceeds in the presence of a seed crystal of the inclusion complex (see scheme). For example, passing Et2O over a mixture of 1 and a seed of 1·(Et2O)3 gives rise to exclusive formation of the 1:3 complex.

The crystal structures of 4-chlorophenoxyacetic acid (4CPA) included in β-cyclodextrin (β-CD) and heptakis(2,3,6-tri-O-methyl)-β-cyclodextrin (TMβCD) have been studied by X-ray diffraction. The 4CPA/β-CD complex crystallizes as a head-to-head dimer in the space group C2 in the Tetrad packing mode. The packing modes of some β-CD dimeric complexes, h...

Heptakis(2,3-di-O-acetyl-6-bromo-6-deoxy)cyclomaltoheptaose has been characterized in aqueous solution by 1D and 2D NMR spectroscopy and in the solid state by X-ray crystallography. In methanol solution, the acetyl groups were found to interact with both inward and outward-pointing protons. This and the strong deshielding of the bridging carbons, r...

The synthesis, purification, and characterization of mono-6-modified-β-cyclodextrins bearing N-attached o-, m-, and p-aminobenzoic acids (2, 3, and 4, respectively) are presented. The structures in aqueous solution were investigated using one- and two-dimensional NMR spectroscopy. Detailed assignment of the spectra together with intramolecular NOE...

The synthesis, purification, and characterization of mono-6-modified-beta-cyclodextrins bearing N-attached o-, m-, and p-aminobenzoic acids (2, 3, and 4, respectively) are presented. The structures in aqueous solution were investigated using one- and two-dimensional NMR spectroscopy. Detailed assignment of the spectra together with intramolecular N...

The present investigation is part of an ongoing study on the influence of the long end-functonalized guest molecules DBA and BNZ in the crystal packing of beta-cyclodextrin (betaCD) dimeric complexes. The title compounds are 2:2 host:guest complexes showing limited host-guest hydrogen bonding at the primary faces of the betaCD dimers. Within the be...

The present investigation is part of an ongoing study on the influence of the long end-functonalized guest molecules DBA and BNZ in the crystal packing of β-cyclodextrin (βCD) dimeric complexes. The title compounds are 2:2 host:guest complexes showing limited host–guest hydrogen bonding at the primary faces of the βCD dimers. Within the βCD cavity...

Photoirradiation of a 2:1 inclusion crystal of 2-pyridone with biphenyl-2,2′-dicarboxylic acid in the solid state gave its trans-anti-dimer. Since photoirradiation of a mixture of biphenyl-2,2′-dicarboxylic acid and an excess of 2-pyridone in the solid state gave the trans-anti-dimer in a quatititative yield, it is clear that inclusion complexation...

β-Cyclodextrin forms a 1:1 host:guest inclusion complex ([2]pseudorotaxane) with 4-[2-(4-aminophenyl)ethyl]-benzenamine (1) in water as determined by 1D and 2D NMRexperiments. In the crystalline state, the structure of the complex has revealed a 2:2 stoichiometry, with two βCD molecules forming head-to-head dimers byH-bonds between the secondary O3...

Derivatives of 3-O-acetyl-18-H-glycyrrhetic acid were synthesized. Their structures and membrane activities were studied.

Journal article