scholarly journals The effect of haem ligands on the redox states of the hexa-haem nitrite reductase from Wolinella succinogenes

1990 ◽  
Vol 271 (1) ◽  
pp. 253-257 ◽  
Author(s):  
R S Blackmore ◽  
P M A Gadsby ◽  
C Greenwood ◽  
A J Thomson
Keyword(s):  
Ligand Binding ◽  
Nitrite Reductase ◽  
Active Site ◽  
Redox State ◽  
Stopped Flow ◽  
Ligand Binding Site ◽  
Wolinella Succinogenes ◽  
Redox States ◽  
Cyanide Binding

The nitrite reductase of Wolinella succinogenes containing six covalently bound haem groups has one haem group that will not reduce fully in the presence of excess Na2S2O4. The effect of the extrinsic ligands CO and cyanide on the redox state of this haem was studied by e.p.r. and magnetic c.d. spectroscopy. It was found that both ligands increased the extent of reduction of this haem group, and that in the case of CO binding the level of reduction was correlated with the extent of CO saturation of the enzyme. Stopped-flow studies of the effect of cyanide binding on the rate of dithionite reduction showed that the rate of reduction of the ligand-binding site was increased in the presence of cyanide. This suggests that reduction of the haem groups at the active site is thermodynamically unfavourable in the absence of an extrinsic ligand. The role of the ‘non-reducing’ haem group and the effect of ligands on this centre and on the rate of reduction are discussed in relation to the reduction of nitrite by this enzyme.

Cyanide Binding to cd1 Nitrite Reductase from Pseudomonas aeruginosa: Role of the Active-Site His369 in Ligand Stabilization

2002 ◽  
Vol 291 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Wenliang Sun ◽  
Marzia Arese ◽  
Maurizio Brunori ◽  
Didier Nurizzo ◽  
Kieron Brown ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Nitrite Reductase ◽  
Active Site ◽  
Cyanide Binding ◽  
Ligand Stabilization

scholarly journals Kinetic studies on the nitrite reductase of Wolinella succinogenes

1986 ◽  
Vol 233 (2) ◽  
pp. 553-557 ◽  
Author(s):  
R Blackmore ◽  
T Brittain
Keyword(s):  
Rate Constant ◽  
Nitrite Reductase ◽  
Flash Photolysis ◽  
Spectral Characteristics ◽  
Order Rate Constant ◽  
Second Order ◽  
Stopped Flow ◽  
Dependent Manner ◽  
Wolinella Succinogenes ◽  
Order Rate

The six haem groups of the nitrite reductase enzyme isolated from Wolinella succinogenes are rapidly reduced by the addition of dithionite (S2O4(2-)). The reduction, however, is not homogeneous. Two of the haem groups, namely those that show spectral characteristics typical of five-co-ordinated haem groups, are reduced in a dithionite-concentration-dependent fashion with a rate limit of 1.5 S-1. The other four haem groups, which show spectral characteristics very similar to those of normal six-co-ordinate c-haem groups, reduce in a linear dithionite-concentration-dependent manner with a second-order rate constant of 150 M-1/2 X S-1. The ratio of the amplitudes of the two reduction phases observed in stopped-flow studies is found to be dependent on the concentration of dithionite used. A model is proposed to account for these observations, and computer simulations show that the model represents a good fit to the experimental data. The two haem groups with five-co-ordinate spectral characteristics bind CO. Flash photolysis of the CO complex exhibits one major recombination process with a linear dependence in rate on CO concentration with a second-order rate constant of 2 × 106 M-1 × S-1. By contrast, stopped-flow mixing of the reduced protein with CO shows a very complex pattern of combination, with most of the observed absorbance change associated with a concentration-independent step. These findings are rationalized in terms of structural changes in the protein consequent to ligand binding.

scholarly journals Human YKL-39 is a pseudo-chitinase with retained chitooligosaccharide-binding properties

2012 ◽  
Vol 446 (1) ◽  
pp. 149-157 ◽  
Author(s):  
Marianne Schimpl ◽  
Christina L. Rush ◽  
Marie Betou ◽  
Ian M. Eggleston ◽  
Anneliese D. Recklies ◽  
...  
Keyword(s):  
Ligand Binding ◽  
Active Site ◽  
Elevated Serum ◽  
Serum Levels ◽  
Chitinase Activity ◽  
Active Site Residues ◽  
Binding Properties ◽  
Binding Partners ◽  
Tryptophan Residues

The chitinase-like proteins YKL-39 (chitinase 3-like-2) and YKL-40 (chitinase 3-like-1) are highly expressed in a number of human cells independent of their origin (mesenchymal, epithelial or haemapoietic). Elevated serum levels of YKL-40 have been associated with a negative outcome in a number of diseases ranging from cancer to inflammation and asthma. YKL-39 expression has been associated with osteoarthritis. However, despite the reported association with disease, the physiological or pathological role of these proteins is still very poorly understood. Although YKL-39 is homologous to the two family 18 chitinases in the human genome, it has been reported to lack any chitinase activity. In the present study, we show that human YKL-39 possesses a chitinase-like fold, but lacks key active-site residues required for catalysis. A glycan screen identified oligomers of N-acetylglucosamine as preferred binding partners. YKL-39 binds chitooligosaccharides and a newly synthesized derivative of the bisdionin chitinase-inhibitor class with micromolar affinity, through a number of conserved tryptophan residues. Strikingly, the chitinase activity of YKL-39 was recovered by reverting two non-conservative substitutions in the active site to those found in the active enzymes, suggesting that YKL-39 is a pseudo-chitinase with retention of chitinase-like ligand-binding properties.

scholarly journals Role of Ligand Binding Site in Modulating Mechanical Properties of Ubiquitin Family Proteins

2021 ◽  
Vol 120 (3) ◽  
pp. 361a-362a
Author(s):  
Mona Gupta ◽  
Ravindra Venkatramani ◽  
Sri Rama Koti Ainavarapu
Keyword(s):  
Mechanical Properties ◽  
Ligand Binding ◽  
Binding Site ◽  
Ligand Binding Site

scholarly journals Role of the Active-Site Solvent in the Thermodynamics of Factor Xa Ligand Binding

2008 ◽  
Vol 130 (9) ◽  
pp. 2817-2831 ◽  
Author(s):  
Robert Abel ◽  
Tom Young ◽  
Ramy Farid ◽  
Bruce J. Berne ◽  
Richard A. Friesner
Keyword(s):  
Ligand Binding ◽  
Active Site ◽  
Factor Xa
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