scholarly journals The interplay of electrostatic and binding interactions determining active centre chemistry and catalytic activity in actinidin and papain

1989 ◽  
Vol 257 (1) ◽  
pp. 309-310 ◽  
Author(s):  
K Brocklehurst ◽  
M O'Driscoll ◽  
D Kowlessur ◽  
I R Phillips ◽  
W Templeton ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Active Centre ◽  
Binding Interactions

Controlled distribution of active centre to enhance catalytic activity of ordered Pd/Co catalytic nano-monolayer

2019 ◽  
Vol 376 ◽  
pp. 228-237 ◽  
Author(s):  
Weili Shang ◽  
Xiangfeng Zeng ◽  
Tiesheng Li ◽  
Wenjian Xu ◽  
Donghui Wei ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Active Centre

Evidence from activation parameters for enzyme active centre desolvation promoted by specific binding interactions

1994 ◽  
Vol 22 (2) ◽  
pp. 213S-213S
Author(s):  
GEOFFREY W. MELLOR ◽  
MARK P. THOMAS ◽  
SHERAZ GUL ◽  
MICHAEL A. NOBLE ◽  
EMRYS W. THOMAS ◽  
...  
Keyword(s):  
Specific Binding ◽  
Activation Parameters ◽  
Active Centre ◽  
Binding Interactions

Rhenium and manganese modified activated carbon as catalyst for methanol decomposition

2007 ◽  
Vol 85 (2) ◽  
pp. 118-123 ◽  
Author(s):  
T Tsoncheva ◽  
S Vankova ◽  
O Bozhkov ◽  
D Mehandjiev
Keyword(s):  
Catalytic Activity ◽  
Activated Carbon ◽  
Carbon Materials ◽  
Catalytic Properties ◽  
Methanol Decomposition ◽  
Complex Character ◽  
Active Centre ◽  
Modified Activated Carbon

Bicomponent manganese and rhenium modified activated carbon materials, prepared by different methods, are studied and compared with the corresponding monocomponent materials as catalysts in methanol decomposition to CO and hydrogen. The best catalytic activity and stability is observed for the sample obtained by simultaneous deposition of Mn and Re precursors. The complex character of the catalytic active centre, including manganese and rhenium irons in various oxidative states, is discussed. The determining role of the Mn(II) ions in the improvement of the catalytic properties is assumed.Key words: rhenium, manganese, activated carbon, methanol decomposition.

scholarly journals Contribution of the active-site metal cation to the catalytic activity and to the conformational stability of phosphotriesterase: temperature- and pH-dependence

2004 ◽  
Vol 380 (3) ◽  
pp. 627-633 ◽  
Author(s):  
Daniel ROCHU ◽  
Nathalie VIGUIÉ ◽  
Frédérique RENAULT ◽  
David CROUZIER ◽  
Marie-Thérèse FROMENT ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Metal Cation ◽  
Active Site ◽  
Ph Dependence ◽  
Conformational Stability ◽  
Maximum Activity ◽  
Active Centre ◽  
Optimum Activity ◽  
Maximum Stability ◽  
Activation Phase

Phosphotriesterase (PTE) detoxifies nerve agents and organophosphate pesticides. The two zinc cations of the PTE active centre can be substituted by other transition metal cations without loss of activity. Furthermore, metal-substituted PTEs display differences in catalytic properties. A prerequisite for engineering highly efficient mutants of PTE is to improve their thermostability. Isoelectric focusing, capillary electrophoresis and steady-state kinetics analysis were used to determine the contribution of the active-site cations Zn2+, Co2+ or Cd2+ to both the catalytic activity and the conformational stability of the corresponding PTE isoforms. The three isoforms have different pI values (7.2, 7.5 and 7.1) and showed non-superimposable electrophoretic titration curves. The overall structural alterations, causing changes in functional properties, were found to be related to the nature of the bound cation: ionic radius and ion electronegativity correlate with Km and kcat respectively. In addition, the pH-dependent activity profiles of isoforms were different. The temperature-dependent profiles of activity showed maximum activity at T≤35 °C, followed by an activation phase near 45–48 °C and then inactivation which was completed at 60 °C. Analysis of thermal denaturation of the PTEs provided evidence that the activation phase resulted from a transient intermediate. Finally, at the optimum activity between pH 8 and 9.4, the thermostability of the different PTEs increased as the pH decreased, and the metal cation modulated stability (Zn2+-, Co2+- and Cd2+-PTE showed different Tm values of 60.5–67 °C, 58–64 °C and 53–64 °C respectively). Requirements for optimum activity of PTE (displayed by Co2+-PTE) and maximum stability (displayed by Zn2+-PTE) were demonstrated.

Tuning the Catalytic Activity of Cyclodextrin-Modified Palladium Nanoparticles through Host−Guest Binding Interactions

Langmuir ◽  
2001 ◽  
Vol 17 (22) ◽  
pp. 6762-6764 ◽  
Author(s):  
Jian Liu ◽  
Julio Alvarez ◽  
Winston Ong ◽  
Esteban Román ◽  
Angel E. Kaifer
Keyword(s):  
Catalytic Activity ◽  
Palladium Nanoparticles ◽  
Binding Interactions ◽  
Guest Binding

Localization of Enolase in the Subfractions of a Breast Cancer Cell Line

2009 ◽  
Vol 64 (9-10) ◽  
pp. 754-758 ◽  
Author(s):  
Ewa Seweryn ◽  
Jadwiga Pietkiewicz ◽  
Iwona S. Bednarz-Misa ◽  
Ireneusz Ceremuga ◽  
Jolanta Saczko ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Plasma Membrane ◽  
Catalytic Activity ◽  
Cancer Cell Line ◽  
Surface Protein ◽  
Active Centre ◽  
Intact Cells ◽  
Human Plasminogen ◽  
Intact Surface ◽  
Mcf 7

Enolase detected on the cell surface may be a receptor for certain ligands, especially for plasminogen. It is important for the pathogen invasiveness and in the development of a tumour. Therefore, we sought to preliminarily determine the enolase location and catalytic activity in the subfractions of MCF-7 cells. The latter was done on intact cells and in subfractions of MCF-7 cells. We identified enolase by immunoblotting. The binding of human plasminogen to enolase was performed by immunoblotting using monoclonal antibodies against plasminogen. The intact MCF-7 cells demonstrated activity of enolase. Enolase in postnuclear and perinuclear fractions is catalyticly active too. We identified the enolase protein in immunoblots of these fractions, except for the nuclear subfraction. These results provide evidence that enolase is present on the intact surface of MCF-7 cells and in post- and perinuclear fractions. The surface protein maintained catalytic activity, which suggests that its location in the plasma membrane didn’t change the active centre of the enzyme

scholarly journals Identification of an arginine residue important for catalytic activity in the primary structure of d-glyceraldehyde 3-phosphate dehydrogenase. Studies with the rat skeletal-muscle enzyme

1981 ◽  
Vol 199 (3) ◽  
pp. 757-765 ◽  
Author(s):  
N D Vospelnikova ◽  
M I Safronova ◽  
E R Shuvalova ◽  
L A Baratova ◽  
S P Kniazev ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Catalytic Activity ◽  
Experimental Evidence ◽  
Primary Structure ◽  
Structural Rearrangements ◽  
Rat Skeletal Muscle ◽  
Active Centre ◽  
Muscle Enzyme ◽  
Tryptic Digest ◽  
Arginine Residues

The reaction of holo-(D-glyceraldehyde 3-phosphate dehydrogenase) (EC 1.2.1.12) from rat skeletal muscle with [14C]butanedione in 0.05 M-NH4HCO3, pH 8.0, resulted in modification (*) of two arginine residues per subunit with a concomitant loss of catalytic activity. From a tryptic digest of the modified protein two radiolabelled peptides were isolated, with the following sequences: (1)Val-Ile-Ile-Asn-Ala-Pro-Thr-Ala-Asp-Ala(Glx,Met,Leu,Phe,Met)Gly-Val-Asx-Arg- Glx(His,Tyr)Ser-Lys and (2) Asp-Ala-Gly-Ala-Thr-Ile-Ala-Leu(Asx,Glx,Arg,Phe,Val)Lys. By comparison of the data with the known sequences of homologous enzymes, the localization of the modified residues was established. The first peptide was identified as corresponding to residues 116--139, the second to residues 293--306. Experimental evidence from this and previous studies suggests that arginine-134 is important for the catalytic activity of the rat muscle enzyme, being involved in structural rearrangements accompanying the organization of the active centre on the binding of coenzyme and substrate.

Concluding remarks

1967 ◽  
Vol 167 (1009) ◽  
pp. 448-448 ◽  
Keyword(s):  
Dielectric Constant ◽  
Catalytic Activity ◽  
Active Sites ◽  
Low Dielectric Constant ◽  
Side Chains ◽  
Polar Medium ◽  
Active Centre ◽  
Low Dielectric ◽  
Globin Chains ◽  
First Time

For the first time we have been able to interpret the catalytic activity of an enzyme in stereochemical terms. It seems rash to generalize from the structure of one enzyme, but we may broaden our base by elevating myoglobin and haemoglobin to the rank of honorary enzymes, as Monod has suggested, and call the haem groups their active sites. What these three proteins have in common is the distribution of polar and nonpolar side chains; the interior of the lysozyme as well as that of the globin chains is made up largely of hydrocarbons, providing a medium of low dielectric constant. In each case the active centre lies in a pocket formed by this non-polar medium, and the pocket contains some polar residues which are essential for activity.

High resolution electron microscopy of lanthanum phosphate crystals

1978 ◽  
Vol 36 (1) ◽  
pp. 274-275
Author(s):  
J. C. Wheatley ◽  
J. M. Cowley
Keyword(s):  
Electron Microscopy ◽  
Catalytic Activity ◽  
High Resolution ◽  
Petroleum Industry ◽  
High Resolution Electron Microscopy ◽  
Lanthanum Phosphate ◽  
Good Catalyst ◽  
Resolution Electron ◽  
Good Catalytic Activity ◽  
Physical And Chemical

Rare-earth phosphates are of particular interest because of their catalytic properties associated with the hydrolysis of many aromatic chlorides in the petroleum industry. Lanthanum phosphates (LaPO4) which have been doped with small amounts of copper have shown increased catalytic activity (1). However the physical and chemical characteristics of the samples leading to good catalytic activity are not known.Many catalysts are amorphous and thus do not easily lend themselves to methods of investigation which would include electron microscopy. However, the LaPO4, crystals are quite suitable samples for high resolution techniques.The samples used were obtained from William L. Kehl of Gulf Research and Development Company. The electron microscopy was carried out on a JEOL JEM-100B which had been modified for high resolution microscopy (2). Standard high resolution techniques were employed. Three different sample types were observed: 669A-1-5-7 (poor catalyst), H-L-2 (good catalyst) and 27-011 (good catalyst).

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