Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.31 (beta-glucuronidase)
 7,680 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The cyclic undecapeptide, cyclosporin (Cs) H, is a potent inhibitor of FMLP-induced superoxide anion (O2-) formation in human neutrophils. We studied the effects of CsH in comparison with those of N-t-butoxycarbonyl-L-phenylalanyl-L-leucyl-L-phenylalanyl-L-leucyl-L- phenylalanine (BocPLPLP), a well known formyl peptide receptor antagonist, and of other Cs on activation of N6,2'-O-dibutyryl adenosine 3:5'-monophosphate-differentiated HL-60 cells and human erythroleukemia cells (HEL cells). CsH inhibited FMLP binding in HL-60 membranes with a Ki (inhibition constant) of 0.10 microM. CsH inhibited activation by FMLP of high affinity GTPase (the enzymatic activity of alpha-subunits of heterotrimeric regulatory guanine nucleotide-binding proteins) in HL-60 membranes with a Ki of 0.79 microM. CsH inhibited the stimulatory effects of FMLP on cytosolic Ca2+ concentration ([Ca2+]i), O2- formation, and beta-glucuronidase release with Ki values of 0.08, 0.24, and 0.45 microM, respectively. BocPLPLP was 14-fold less potent than CsH in inhibiting FMLP binding and 4- to 6-fold less potent than CsH in inhibiting FMLP-induced GTP hydrolysis, rises in [Ca2+]i, O2- formation, and beta-glucuronidase release. CsA reduced FMLP-induced O2- formation by 20%, but CsB, CsC, CsD, and CsE did not. CsA, CsB, CsC, CsD, and CsE did not affect FMLP-induced rises in [Ca2+]i. BocPLPLP inhibited leukotriene B4-induced rises in [Ca2+]i with a Ki of 0.33 microM, whereas CsH showed no inhibitory effect. CsH and BocPLPLP did not inhibit the rises in [Ca2+]i induced by several other stimuli in HL-60 cells and HEL cells. Our results show that 1) CsH is a more potent formyl peptide receptor antagonist than BocPLPLP; 2) unlike BocPLPLP, CsH is selective; and 3) N-methyl-D-valine which is present at position 11 of the amino acid sequence of CsH but not of other Cs is crucial for FMLP antagonism.
 ...
PMID:Cyclosporin H is a potent and selective formyl peptide receptor antagonist. Comparison with N-t-butoxycarbonyl-L-phenylalanyl-L-leucyl-L-phenylalanyl-L- leucyl-L-phenylalanine and cyclosporins A, B, C, D, and E. 838 97

Stereochemically constrained extended beta-antiparallel and folded beta-turn analogs of the chemotactic agent N-formyl-Met-Leu-Phe-OH were tested for their ability to induce the release of beta-glucuronidase from human and rabbit neutrophils. Selected biologically active peptides were further examined for their capacity to inhibit the binding of f-Met-Leu-[3H]Phe to whole human neutrophils at 4 degrees C. The results suggest that Dpg2 analogs with the extended backbone are significantly more potent in human peripheral blood neutrophils than the folded beta-turn analogs. Surprisingly, in rabbit peritoneal neutrophils, the extended Dpg2 analog appears to be marginally less active than the flexible parent peptide and the folded Ac6c2 analog. In human neutrophils, the secretagogue activity increases in the following order with alteration in the C-terminal functions: -CONH2 < -COOMe < -COOH << -COOBzl. However, this order of potency differs from that observed for the rabbit formyl peptide receptor (-COOH < -COOMe < -CONH2 << -COOBzl). In human neutrophils, the peptides' ability to compete for the receptor binding site of f-Met-Leu-[3H]Phe correlates well with their secretagogue potency. The results provide convincing evidence for the existence of subtle differences between human peripheral blood neutrophils and rabbit peritoneal neutrophils with regard to ligand-receptor interactions of constrained chemotactic peptides. What is new and novel in this report is that constrained peptides can distinguish between the rabbit and human chemotactic peptide receptors which have so far been believed to have similar response to secretagogue agents. The data emphasize that directly relating the secretagogue activity observed in rabbit neutrophils to that observed in human neutrophils may not be unequivocal.
 ...
PMID:Subtle differences between human and rabbit neutrophil receptors shown by the secretagogue activity of constrained formyl peptides. 901 22

Formyl peptide receptor-like 1 (FPRL1) is a G protein-coupled receptor that binds natural and synthetic peptides as well as lipoxin A(4) and mediates important biological functions. To facilitate its pharmacological characterization, we screened a compound library and identified a substituted quinazolinone (Quin-C1, 4-butoxy-N-[2-(4-methoxy-phenyl)-4-oxo-1,4-dihydro-2H-quinazolin-3-yl]-benzamide) as a ligand for FPRL1. Quin-C1 induces chemotaxis and secretion of beta-glucuronidase in peripheral blood neutrophils with a potency of approximately 1/1000 of that of the peptide agonist WKYMVm. In studies using transfected rat basophilic leukemia (RBL) cell lines expressing either formyl peptide receptor or FPRL1, Quin-C1 induced enzyme release from RBL-FPRL1 but not RBL-FPR cells. Likewise, Quin-C1 selectively stimulates calcium mobilization in RBL-FPRL1 cells, a response that was markedly inhibited by pertussis toxin. Quin-C1 also stimulates phosphorylation of extracellular signal-regulated protein kinases 1 and 2 and induces internalization of an FPRL1 fused to green fluorescent protein. In degranulation assays, both the FPRL1-selective peptide agonist MMK1 and Quin-C1 exhibited lower efficacy and potency than WKYMVm, with EC(50) values of 7.17 x 10(-8) M and 1.88 x 10(-6) M, respectively, compared with the EC(50) value for WKYMVm (2.29 x 10(-8) M). However, Quin-C1 did not induce neutrophil superoxide generation at up to 100 microM. Based on these results, we conclude that Quin-C1 is a novel nonpeptide ligand that binds to FPRL1 and selectively stimulates FPRL1-mediated functions. Quin-C1 is a prototype of substituted quinazolinones based on which further structural modifications may be made to improve its efficacy and potency for FPRL1.
 ...
PMID:A novel nonpeptide ligand for formyl peptide receptor-like 1. 1530 62