Flavodoxin from Anabaena 7120: uniform nitrogen-15 enrichment and hydrogen-1, nitrogen-15, and phosphorus-31 NMR investigations of the flavin mononucleotide binding site in the reduced and oxidized states

Biochemistry ◽  
1988 ◽  
Vol 27 (1) ◽  
pp. 136-142 ◽  
Author(s):  
Brian J. Stockman ◽  
William M. Westler ◽  
Eddie S. Mooberry ◽  
John L. Markley
1991 ◽  
pp. 377-380
Author(s):  
Brian J. Stockman ◽  
Andrzej M. Krezcl ◽  
John B. Olson ◽  
Ed S. Mooberry ◽  
John L. Markley

2019 ◽  
Vol 20 (20) ◽  
pp. 5083 ◽  
Author(s):  
Sonia Arilla-Luna ◽  
Ana Serrano ◽  
Milagros Medina

Bifunctional FAD synthases (FADSs) catalyze FMN (flavin mononucleotide) and FAD (flavinadenine dinucleotide) biosynthesis at their C-riboflavin kinase (RFK) and N-FMN:adenylyltransferase (FMNAT) modules, respectively. Biophysical properties and requirements for their FMNAT activity differ among species. Here, we evaluate the relevance of the integrity of the binding site of the isoalloxazine of flavinic substrates for FMNAT catalysis in Corynebacterium ammoniagenes FADS (CaFADS). We have substituted P56 and P58, belonging to a conserved motif, as well as L98. These residues shape the isoalloxazine FMNAT site, although they are not expected to directly contact it. All substitutions override enzyme ability to transform substrates at the FMNAT site, although most variants are able to bind them. Spectroscopic properties and thermodynamic parameters for the binding of ligands indicate that mutations alter their interaction modes. Substitutions also modulate binding and kinetic properties at the RFK site, evidencing the crosstalk of different protomers within CaFADS assemblies during catalysis. In conclusion, despite the FMNAT site for the binding of substrates in CaFADS appearing as a wide open cavity, it is finely tuned to provide the competent binding conformation of substrates. In particular, P56, P58 and L98 shape the isoalloxazine site to place the FMN- and FAD-reacting phosphates in optimal geometry for catalysis.


Biochemistry ◽  
1990 ◽  
Vol 29 (41) ◽  
pp. 9600-9609 ◽  
Author(s):  
Brian J. Stockman ◽  
Andrzej M. Krezel ◽  
John L. Markley ◽  
Karin G. Leonhardt ◽  
Neil A. Straus

1996 ◽  
Vol 76 (01) ◽  
pp. 005-008 ◽  
Author(s):  
Jean Claude Lormeau ◽  
Jean Pascal Herault ◽  
Jean Marc Herbert

SummaryWe examined the effect of the synthetic pentasaccharide representing the minimal binding site of heparin to antithrombin on the antithrombin-mediated inactivation of factor Vila bound to tissue factor. This effect was compared to the effect of unfractionated heparin. Using purified recombinant human coagulation factors and either a clotting or an amidolytic assay for the determination of the residual activity of factor Vila, we showed that the pentasaccharide was an efficient antithrombin-dependent inhibitor of the coagulant activity of tissue factor-factor Vila complex. In our experimental conditions, assuming a mean MW of 14,000 for heparin, the molar pseudo-first order rate constants for ATIII-mediated FVIIa inhibition by ATIII-binding heparin and by the synthetic pentasaccharide were found to be similar with respective values of 104,000 ± 10,500 min-1 and 112,000 ± 12,000 min-1 (mean ± s.e.m., n = 3)


1995 ◽  
Vol 73 (05) ◽  
pp. 829-834 ◽  
Author(s):  
Jaya Padmanabhan ◽  
David C Sane

SummaryThe PAI-1 binding site for VN was studied using two independent methods. PAI-1 was cleaved by Staph V8 protease, producing 8 fragments, only 2 of which bound to [125I]-VN. These fragments were predicted to overlap between residues 91-130. Since PAI-2 has structural homology to PAI-1, but does not bind to vitronectin, chimeras of PAI-1 and PAI-2 were constructed. Four chimeras, containing PAI-1 residues 1-70,1-105,1-114, and 1-167 were constructed and expressed in vitro. PAI-1, PAI-2, and all of the chimeras retained inhibitory activity for t-PA, but only the chimera containing PAI-1 residues 1-167 formed a complex with VN. Together, these results predict that the VN binding site of PAI-1 is between residues 115-130.


1997 ◽  
Vol 77 (01) ◽  
pp. 137-142 ◽  
Author(s):  
Kiyoshi Tachikawa ◽  
Keiji Hasurni ◽  
Akira Endo

SummaryPlasminogen binds to endothelial and blood cells as well as to fibrin, where the zymogen is efficiently activated and protected from inhibition by α2-antiplasmin. In the present study we have found that complestatin, a peptide-like metabolite of a streptomyces, enhances binding of plasminogen to cells and fibrin. Complestatin, at concentrations ranging from 1 to 5 μM, doubled 125I-plasminogen binding to U937 cells both in the absence and presence of lipoprotein(a), a putative physiological competitor of plasminogen. The binding of 125I-plasminogen in the presence of complestatin was abolished by e-aminocaproic acid, suggesting that the lysine binding site(s) of the plasminogen molecule are involved in the binding. Equilibrium binding analyses indicated that complestatin increased the maximum binding of 125I-plasminogen to U937 cells without affecting the binding affinity. Complestatin was also effective in increasing 125I-plasminogen binding to fibrin, causing 2-fold elevation of the binding at ~1 μM. Along with the potentiation of plasminogen binding, complestatin enhanced plasmin formation, and thereby increased fibrinolysis. These results would provide a biochemical basis for a pharmacological stimulation of endogenous fibrinolysis through a promotion of plasminogen binding to cells and fibrin.


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