[FeFe]-Hydrogenase H-cluster mimics mediated by naphthalene monoimide derivatives of peri-substituted dichalcogenides

2017 ◽  
Vol 46 (34) ◽  
pp. 11180-11191 ◽  
Author(s):  
Hassan Abul-Futouh ◽  
Yulian Zagranyarski ◽  
Carolin Müller ◽  
Martin Schulz ◽  
Stephan Kupfer ◽  
...  
Keyword(s):  
Active Site ◽  
Derivatives Of ◽  
Synthetic Models

Synthetic models of the active site of [FeFe]-hydrogenase containing naphthalene monoimide as bridging linker.

Acyl-Enzymes as Thrombolytic Agents in Dog Models of Venous Thrombosis and Pulmonary Embolism

1984 ◽  
Vol 51 (02) ◽  
pp. 248-253 ◽  
Author(s):  
R J Dupe ◽  
P D English ◽  
R A G Smith ◽  
J Green
Keyword(s):  
Pulmonary Embolism ◽  
Side Effects ◽  
Venous Thrombosis ◽  
Active Site ◽  
Acute Pulmonary Embolism ◽  
Quantitative Model ◽  
Beagle Dog ◽  
Thrombosis Model ◽  
Derivatives Of

SummaryA quantitative model of venous thrombosis in the beagle dog is described. The model was adapted to permit ageing of isolated experimental clots in vivo. A model of acute pulmonary embolism in this species is also described. In the venous thrombosis model, infusion of streptokinase (SK) or SK-activated human plasmin gave significant lysis but bolus doses of SK. plasmin complex were ineffective. Active site anisoylated derivatives of SK. plasminogen complex, SK-activated plasmin and activator-free plasmin were all active when given as bolus doses in both models. At lytic doses, the acyl-enzymes caused fewer side-effects attributable to plasminaemia than the corresponding unmodified enzymes.

The melanocyte stimulating activity of N-nitroso-2-chloroethyl-carbamoyl derivatives of α-melanotropin fragments

1988 ◽  
Vol 53 (11) ◽  
pp. 2574-2582 ◽  
Author(s):  
Hedvig Medzihradszky-Schweiger ◽  
Helga Süli-Vargha ◽  
József Bódi ◽  
Kálmán Medzihradszky
Keyword(s):  
Biological Activity ◽  
Active Site ◽  
Frog Skin ◽  
Terminal Sequence ◽  
Subsequent Reaction ◽  
Affinity Labels ◽  
Derivatives Of

A number of N-nitroso-2-chloroethyl-carbamoyl (Q(NO)) derivatives of α-melanotropin fragments have been synthesized and their effect on the frog skin melanocytes studied. Peptides substituted in this way possess the biological activity of the parent compounds, indicating that they preserved their receptor recognizing ability. These compounds can therefore serve as affinity labels. Some of these derivatives, related to the C-terminal sequence of α-melanotropin show prolonged darkening reaction, which does not influence the subsequent reaction of melanocytes with α-melanotropin. The Q(NO)-derivative of a fragment derived from the classical active site of the hormone shows, however, inhibition of the effect of α-melanotropin. It can be concluded that the latter peptide acts through the melanotropin receptor, while others, related to the C-terminal sequence of the hormone through another mechanism.

ACTIVE SITE-SELECTIVE LABELING OF THROMBIN WITH FLUORESCENCE PROBES USING THI0ESTER DERIVATIVES OF PEPTIDE-CHL0R0METHYL KETONES

1987 ◽  
Author(s):  
Paul E Bock
Keyword(s):  
Active Site ◽  
Active Sites ◽  
Thiol Group ◽  
Fluorescence Probes ◽  
Red Cross ◽  
Chloromethyl Ketone ◽  
Human Thrombin ◽  
Reaction Stoichiometry ◽  
Site Selective ◽  
Derivatives Of

Active site-directed inactivation of a serine protease with a thioester derivative of a peptide-chloromethyl ketone followed by reaction of the unique thiol group generatedin the presence of hydroxylamine with a fluorophore-iodoacetamide hasbeen investigated as a new method for covalent incorporation of extrinsic fluorescence probes into the active sites of blood coagulation proteases. The specificity of labeling by this method was evaluated by quantitation of the reactions between human thrombin, acetylthioacetyl-D-Phe-Pro-ArgCH2Cl (ATA-FPRCK) and 5-iodoacetamidofluorescein(IAF).ATA-FPRCK was synthesized by reaction of FPRCK with succinimidylacetylthioacetate and purified by chromatography on SP-Sephadex and Sephadex G10. Titrations of the loss of thrombin chromogenic substrate activity with ATA-FPRCK were linear, with end points of 1.1-1.2 mol ATA-FPRCK added/mol active sites, consistent with a reaction stoichiometry of 1 and the ∽90% purity of the compound estimated by reverse-phase HPLC.Inactivation of thrombin wasquantitatively correlated with incorporation of the thioester, with a maximum of 1.04 mol/mol active sites.IAF labeling of ATA-FPR-thrombin inthe presence of 0.1M NH20H yielded a maximu of 0.96 mol IAF incorporated/mol active sites in a reaction accompanied by loss of the thiol group. Incorporation of ATA-FPRCK wasdependent on thefunctional thrombin active site, asdemonstrated by less than 4%thioester or IAF incorporation for the enzyme previously inactivated with FPRCK. I conclude that active site-selective fluorescence labelingcan be achieved by the method described here with the advantage of a wide choice in the properties of theprobe incorporated. In addition, a 2.3-fold difference in fluorescenceintensity was observed for 2,6-ANS derivatives of ATA-FPR-thrombin andATA-D-Phe-Phe-Arg-thrombin, indicating that the spectral properties ofenvironmentally sensitive fluorescence probes are influenced by the structure of the peptide inhibitor.Supported in part by a grant from the American National Red Cross.

Synthetic models for the active site of hemocyanin

1989 ◽  
Vol 36 (3-4) ◽  
pp. 327
Author(s):  
T.N. Sorrell ◽  
M.L. Garrity ◽  
J.R. Richards ◽  
V.A. Vankai
Keyword(s):  
Active Site ◽  
Synthetic Models

scholarly journals Albino mutants of Streptomyces glaucescens tyrosinase

1991 ◽  
Vol 274 (3) ◽  
pp. 707-713 ◽  
Author(s):  
M P Jackman ◽  
A Hajnal ◽  
K Lerch
Keyword(s):  
Active Site ◽  
Critical Role ◽  
Site Directed Mutagenesis ◽  
Mutant Proteins ◽  
Carbonyl Derivatives ◽  
Hydrogen Bonding Interactions ◽  
Albino Phenotype ◽  
Derivatives Of ◽  
Streptomyces Glaucescens

Site-directed mutagenesis was used to determine the functional role of several residues of Streptomyces glaucescens tyrosinase. Replacement of His-37, -53, -193 or -215 by glutamine yields albino phenotypes, as determined by expression on melanin-indicator plates. The purified mutant proteins display no detectable oxy-enzyme and increased Cu lability at the binuclear active site. The carbonyl derivatives of H189Q and H193Q luminesce, with lambda max. displaced more than 25 nm to a longer wavelength compared with native tyrosinase. The remaining histidine mutants display no detectable luminescence. The results are consistent with these histidine residues (together with His-62 and His-189 reported earlier) acting as Cu ligands in the Streptomyces glaucescens enzyme. Conservative substitution of the invariant Asn-190 by glutamine also gives an albino phenotype, no detectable oxy-enzyme and labilization of active-site Cu. The luminescence spectrum of carbonyl-N190Q, however, closely resembles that of the native enzyme under conditions promoting double Cu occupancy of the catalytic site. A critical role for Asn-190 in active-site hydrogen-bonding interactions is proposed.

Synthetic Models of the Active Site of Catechol Oxidase: Mechanistic Studies

ChemInform ◽  
2006 ◽  
Vol 37 (48) ◽  
Author(s):  
Iryna A. Koval ◽  
Patrick Gamez ◽  
Catherine Belle ◽  
Katalin Selmeczi ◽  
Jan Reedijk
Keyword(s):  
Active Site ◽  
Catechol Oxidase ◽  
Mechanistic Studies ◽  
Synthetic Models

Synthetic models of the active site of catechol oxidase: mechanistic studies

2006 ◽  
Vol 35 (9) ◽  
pp. 814 ◽  
Author(s):  
Iryna A. Koval ◽  
Patrick Gamez ◽  
Catherine Belle ◽  
Katalin Selmeczi ◽  
Jan Reedijk
Keyword(s):  
Active Site ◽  
Catechol Oxidase ◽  
Mechanistic Studies ◽  
Synthetic Models
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