RESUMO
Phosphoglycosyltransferases (PGTs) represent "gatekeeper" enzymes in complex glycan assembly pathways by catalyzing transfer of a phosphosugar from an activated nucleotide diphosphosugar to a membrane-resident polyprenol phosphate. The unique structures of selected nucleoside antibiotics, such as tunicamycin and mureidomycin A, which are known to inhibit comparable biochemical transformations, are exploited as the foundation for the development of modular synthetic inhibitors of PGTs. Herein we present the design, synthesis, and biochemical evaluation of two readily manipulatable modular scaffolds as inhibitors of monotopic bacterial PGTs. Selected compounds show IC50 values down to the 40â µm range, thereby serving as lead compounds for future development of selective and effective inhibitors of diverse PGTs of biological and medicinal interest.
Assuntos
Antibacterianos/química , Glicosiltransferases/química , Glicosiltransferases/síntese química , Nucleosídeos/química , Tunicamicina/química , Biocatálise , Glicosiltransferases/metabolismo , Hidrólise , Concentração Inibidora 50 , Estrutura MolecularRESUMO
The availability of structural information on glycosyltransferases is beginning to make structure-based reengineering of these enzymes possible. Mutant glycosyltransferases have been generated that can transfer a sugar residue with a chemically reactive unique functional group to a sugar moiety of glycoproteins, glycolipids, and proteoglycans (glycoconjugates). The presence of modified sugar moiety on a glycoprotein makes it possible to link bioactive molecules via modified glycan chains, thereby assisting in the assembly of bionanoparticles that are useful for developing the targeted drug delivery system and contrast agents for magnetic resonance imaging. The reengineered recombinant glycosyltransferases also make it possible to (1) remodel the oligosaccharide chains of glycoprotein drugs, and (2) synthesize oligosaccharides for vaccine development.
Assuntos
Meios de Contraste/síntese química , Sistemas de Liberação de Medicamentos/métodos , Glicoconjugados/química , Glicoconjugados/genética , Glicosiltransferases/síntese química , Glicosiltransferases/genética , Imageamento por Ressonância Magnética/métodos , Animais , Engenharia Genética/métodos , HumanosRESUMO
BACKGROUND: Most studies indicate that the incidence of graft-versus-host disease (GVHD) is not increased in ABO-mismatched allogeneic peripheral blood progenitor cell transplantation. These studies exclusively looked at ABO phenotypes without considering the fact that different genotypes hide behind identical phenotypes that encode for different sets of glycosyltransferases, thus providing a source for minor histocompatibility antigens (mHags). STUDY DESIGN AND METHODS: Therefore, whether peptides derived from ABO glycosyltransferases are capable of stimulating peptide-specific T cells was investigated. T-cell responses were identified by measuring intracellular interleukin-2 expression. RESULTS: Individuals with ABO genotypes encoding glycosyltransferases lacking the peptide sequences used for stimulation showed T-cell responses, whereas those expressing glycosyltransferases containing the respective peptide sequences proved to be tolerant, indicating that ABO peptides are allogeneic and may act as mHags. Interestingly, even ABO*O individuals were tolerant to O glycosyltransferase-derived peptides, which strongly suggests that truncated O transferases are expressed. CONCLUSION: Considering allelic ABO sequences, at least 15 percent of all phenotypically ABO-matched transplant pairs can be expected to have genotype constellations relevant to GVHD. Therefore, the genotype behind the ABO blood group phenotype should be considered to answer the question of whether ABO mismatch is a risk factor of GVHD.
Assuntos
Sistema ABO de Grupos Sanguíneos/imunologia , Glicosiltransferases/genética , Antígenos de Histocompatibilidade Menor/imunologia , Transplante de Células-Tronco de Sangue Periférico , Transplante Homólogo/imunologia , Sistema ABO de Grupos Sanguíneos/genética , Biomarcadores/sangue , Incompatibilidade de Grupos Sanguíneos/imunologia , Células Cultivadas , Citometria de Fluxo , Glicosiltransferases/síntese química , Glicosiltransferases/química , Glicosiltransferases/farmacologia , Doença Enxerto-Hospedeiro/imunologia , Humanos , Interleucina-2/metabolismo , Leucócitos Mononucleares/efeitos dos fármacos , Ativação Linfocitária , Antígenos de Histocompatibilidade Menor/genética , Modelos Imunológicos , Polimorfismo Genético , Fatores de Risco , Linfócitos T/química , Linfócitos T/imunologiaRESUMO
We detected a human humoral peptide that deglycosylates mouse antibody IgE, and found that this peptide had the amino acid sequence ADSGEGDFLAEGGGV. The peptide synthesized according to the sequence also deglycosylated the antibody IgE. The deglycosylated IgE did not induce mouse systemic anaphylaxis. Human fibrinopeptide A has the amino acid sequence indicated above, and a polypeptide extracted from human urine showed an antiallergic effect on humans and mice, which strongly suggests that fibrinopeptide A mediates allergic reaction via antibody IgE-deglycosylation, and is excreted as a polypeptide in urine.