Search results for "peptidase"
showing 10 items of 567 documents
Pyrrolomycins as antimicrobial agents. Microwave-assisted organic synthesis and insights into their antimicrobial mechanism of action
2019
Abstract New compounds able to counteract staphylococcal biofilm formation are needed. In this study we investigate the mechanism of action of pyrrolomycins, whose potential as antimicrobial agents has been demonstrated. We performed a new efficient and easy method to use microwave organic synthesis suitable for obtaining pyrrolomycins in good yields and in suitable amount for their in vitro in-depth investigation. We evaluate the inhibitory activity towards Sortase A (SrtA), a transpeptidase responsible for covalent anchoring in Gram-positive peptidoglycan of many surface proteins involved in adhesion and in biofilm formation. All compounds show a good inhibitory activity toward SrtA, havi…
Discovery and structure-activity relationship studies of irreversible benzisothiazolinone-based inhibitors against Staphylococcus aureus sortase A tr…
2014
Gram-positive bacteria, in general, and staphylococci, in particular, are the widespread cause of nosocomial and community-acquired infections. The rapid evolvement of strains resistant to antibiotics currently in use is a serious challenge. Novel antimicrobial compounds have to be developed to fight these resistant bacteria, and sortase A, a bacterial cell wall enzyme, is a promising target for novel therapies. As a transpeptidase that covalently attaches various virulence factors to the cell surface, this enzyme plays a crucial role in the ability of bacteria to invade the host's tissues and to escape the immune response. In this study we have screened a small molecule library against rec…
Altered pore-forming properties of proteolytically nicked staphylococcal alpha-toxin
1993
Staphylococcal alpha-toxin is a single-chain polypeptide with a molecular weight of 34,000 that hexamerizes in lipid bilayers to form pores of 1-1.5 nm effective diameter in membranes. We demonstrate that limited proteolysis of purified alpha-toxin with proteinase K generates a hemolytically active product that yields one major protein band of 17-18 kDa in SDS-polyacrylamide gel electrophoresis. The 17-18-kDa protein band harbors two major fragments of similar size representing the N- and C-terminal halves, which remain associated with each other in non-denaturing buffers but dissociate in 6 M urea. Dissociation in urea leads to loss of hemolytic activity. In contrast, unnicked alpha-toxin …
Novel pathogenic mechanism of microbial metalloproteinases: liberation of membrane-anchored molecules in biologically active form exemplified by stud…
1996
Certain membrane-anchored proteins, including several cytokines and cytokine receptors, can be released into cell supernatants through the action of endogenous membrane-bound metalloproteinases. The shed molecules are then able to fulfill various biological functions; for example, soluble interleukin-6 receptor (sIL-6R) can bind to bystander cells, rendering these cells sensitive to the action of IL-6. Using IL-6R as a model substrate, we report that the metalloproteinase from Serratia marcescens mimics the action of the endogenous shedding proteinase. Treatment of human monocytes with the bacterial protease led to a rapid release of sIL-6R into the supernatant. This effect was inhibitable …
Asymmetric Disulfanylbenzamides as Irreversible and Selective Inhibitors of Staphylococcus aureus Sortase A
2020
Abstract Staphylococcus aureus is one of the most frequent causes of nosocomial and community‐acquired infections, with drug‐resistant strains being responsible for tens of thousands of deaths per year. S. aureus sortase A inhibitors are designed to interfere with virulence determinants. We have identified disulfanylbenzamides as a new class of potent inhibitors against sortase A that act by covalent modification of the active‐site cysteine. A broad series of derivatives were synthesized to derive structure‐activity relationships (SAR). In vitro and in silico methods allowed the experimentally observed binding affinities and selectivities to be rationalized. The most active compounds were f…
Individual stereoisomers of phosphinic dipeptide inhibitor of leucine aminopeptidase
2008
Abstract Individual stereoisomers of the phosphinic pseudodipeptide hPheψ[P(O)(OH)CH2]Phe were obtained by stereoselective liquid chromatographic separation as N- and C-terminally protected derivative on quinidine carbamate modified silica stationary phase. The stereoisomeric purity, exceeding 95% for each fraction, was determined before and after deprotection using two independent methods. The absolute configuration was rationally assigned by application of enantiomerically pure phosphinic acid substrates in the synthetic procedure and correlation with biological activity of the products. Substantial differences in inhibition of leucine aminopeptidase by the individual isomers revealed nov…
Recombinant NeutraLite Avidin: a non-glycosylated, acidic mutant of chicken avidin that exhibits high affinity for biotin and low non-specific bindin…
2000
AbstractA recombinant non-glycosylated and acidic form of avidin was designed and expressed in soluble form in baculovirus-infected insect cells. The mutations were based on the same principles that guided the design of the chemically and enzymatically modified avidin derivative, known as NeutraLite Avidin. In this novel recombinant avidin derivative, five out of the eight arginine residues were replaced with neutral amino acids, and two of the lysine residues were replaced by glutamic acid. In addition, the carbohydrate-bearing asparagine-17 residue was altered to an isoleucine, according to the known sequences of avidin-related genes. The resultant mutant protein, termed recombinant Neutr…
Determinants essential for the transmissible gastroenteritis virus-receptor interaction reside within a domain of aminopeptidase-N that is distinct f…
1994
The swine-specific coronavirus transmissible gastroenteritis virus (TGEV) uses pig aminopeptidase-N (pAPN) as a cellular receptor. We showed that the human aminopeptidase-N (hAPN) cannot substitute for pAPN in this respect, although the two enzymes have 80% amino acid sequence identity. In order to map the TGEV binding site on pAPN, we constructed a series of APN cDNA chimeras between pAPN and hAPN and analyzed them for their capacity to confer infectivity. The region between residues 717 and 813 was found to be essential for infectivity. This region also contains the epitopes for three TGEV-blocking monoclonal antibodies directed against pAPN. These data support the view that the catalytic…
Regulation of B cell homeostasis and activation by the tumor suppressor gene CYLD
2007
B cell homeostasis is regulated by multiple signaling processes, including nuclear factor-kappaB (NF-kappaB), BAFF-, and B cell receptor signaling. Conditional disruption of genes involved in these pathways has shed light on the mechanisms governing signaling from the cell surface to the nucleus. We describe a novel mouse strain that expresses solely and excessively a naturally occurring splice variant of CYLD (CYLD(ex7/8) mice), which is a deubiquitinating enzyme that is integral to NF-kappaB signaling. This shorter CYLD protein lacks the TRAF2 and NEMO binding sites present in full-length CYLD. A dramatic expansion of mature B lymphocyte populations in all peripheral lymphoid organs occur…
Hematopoietic stem cell quiescence and function are controlled by the CYLD–TRAF2–p38MAPK pathway
2015
Tesio at al. identify a novel pathway controlled by the tumor suppressor and deubiquitinase cylindromatosis (CYLD), which is involved in the regulation of hematopoietic stem cell quiescence and repopulation potential.