Role of Protein Dynamics in Reaction Rate Enhancement by Enzymes

2005 ◽  
Vol 127 (43) ◽  
pp. 15248-15256 ◽  
Author(s):  
Pratul K. Agarwal
Keyword(s):  
Protein Dynamics ◽  
Reaction Rate ◽  
Rate Enhancement

scholarly journals 155 The role of solvent mobility in protein dynamics

2015 ◽  
Vol 33 (sup1) ◽  
pp. 100-101
Author(s):  
Qiong Yang ◽  
Peng Sang ◽  
Shu-Qun Liu
Keyword(s):  
Protein Dynamics ◽  
Role Of Solvent

Probing catalytic rate enhancement during intramembrane proteolysis

2016 ◽  
Vol 397 (9) ◽  
pp. 907-919 ◽  
Author(s):  
Elena Arutyunova ◽  
Cameron C. Smithers ◽  
Valentina Corradi ◽  
Adam C. Espiritu ◽  
Howard S. Young ◽  
...  
Keyword(s):  
Active Site ◽  
Serine Proteases ◽  
Homology Model ◽  
Intramembrane Proteolysis ◽  
Oxyanion Hole ◽  
Rate Enhancement ◽  
Transition State Stabilization ◽  
The Family ◽  
Catalytic Dyad

Abstract Rhomboids are ubiquitous intramembrane serine proteases involved in various signaling pathways. While the high-resolution structures of the Escherichia coli rhomboid GlpG with various inhibitors revealed an active site comprised of a serine-histidine dyad and an extensive oxyanion hole, the molecular details of rhomboid catalysis were unclear because substrates are unknown for most of the family members. Here we used the only known physiological pair of AarA rhomboid with its psTatA substrate to decipher the contribution of catalytically important residues to the reaction rate enhancement. An MD-refined homology model of AarA was used to identify residues important for catalysis. We demonstrated that the AarA active site geometry is strict and intolerant to alterations. We probed the roles of H83 and N87 oxyanion hole residues and determined that substitution of H83 either abolished AarA activity or reduced the transition state stabilization energy (ΔΔG‡) by 3.1 kcal/mol; substitution of N87 decreased ΔΔG‡ by 1.6–3.9 kcal/mol. Substitution M154, a residue conserved in most rhomboids that stabilizes the catalytic general base, to tyrosine, provided insight into the mechanism of nucleophile generation for the catalytic dyad. This study provides a quantitative evaluation of the role of several residues important for hydrolytic efficiency and oxyanion stabilization during intramembrane proteolysis.

THE ROLE OF ALPHA-KETOLS IN THE LOW-SUGAR REDOX RECIPE FOR LOW TEMPERATURE EMULSION COPOLYMERIZATION

1951 ◽  
Vol 29 (11) ◽  
pp. 949-958
Author(s):  
R. J. Orr ◽  
H. Leverne Williams
Keyword(s):  
Free Radical ◽  
Ferrous Iron ◽  
Reaction Rate ◽  
Catalyst System ◽  
Emulsion Copolymerization ◽  
Peroxy Compounds ◽  
Induced Decomposition ◽  
Amine Compounds ◽  
Better Than

It was found that the induced decomposition of peroxy compounds could lead to faster rates of polymerization or practical rates of polymerization at lower temperatures. In Germany polymerization recipes were developed containing a peroxy compound in the oil phase, a reducer in the aqueous phase and a metal carrier. This idea was transferred to America after the war and became the basis of the present recipes used in the production of cold rubbers. As reducers the most commonly used appear to be digested d-glucose or an excess of ferrous iron but recently the polyamines and other amine compounds have been found to be quite effective. The mixture of amine and sugar was better than either alone. It has been shown that this mixture will function in the presence of reactive monomers such as acrylonitrile. The role of such reducers is of considerable interest so that further studies were undertaken. The results obtained may be illustrated by acetoin. As the amount of acetoin is increased in the recipe the amount of ferrous iron required for maximal conversion in a given time is decreased. This is because at higher than the optimal amounts, although the reaction rate is still increasing, the catalyst system is rapidly exhausted so that the reaction dies at a lower conversion. The data can be explained by assuming formation of free radicals by the induced decomposition of the peroxide either by the acetoin, the ferrous iron, or a complex between the iron and acetoin. This free radical then initiates polymerization. The acetoin free radical residue can induce the further decomposition of the peroxide or possibly can reduce ferric iron to ferrous. Other compounds yield similar results.

Extremely enhanced contaminant decomposition catalyzed by hemin via the coupling of persistent free radicals and ascorbic acid

2015 ◽  
Vol 51 (89) ◽  
pp. 16139-16142 ◽  
Author(s):  
Yuyuan Yao ◽  
Bin Jiang ◽  
Yajun Mao ◽  
Juan Chen ◽  
Zhenfu Huang ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Ascorbic Acid ◽  
Free Radicals ◽  
Reactive Oxygen ◽  
Environmental Pollutant ◽  
Ros Generation ◽  
Oxygen Species ◽  
Positive Role ◽  
Rate Enhancement

A positive role of PFRs in enhancing reactive oxygen species (ROS) generation for an extreme rate enhancement in environmental pollutant decomposition is reported.

THE ROLE OF ADSORPTION IN CONTROLLING THE RATE OF REACTION OF CHLORAMBUCIL WITH PROTEIN

1963 ◽  
Vol 41 (4) ◽  
pp. 931-939 ◽  
Author(s):  
J. H. Linford
Keyword(s):  
Molecular Weight ◽  
Carboxylic Acid ◽  
Bovine Serum Albumin ◽  
Inverse Relationship ◽  
Reaction Rate ◽  
The Other ◽  
Alkylation Reaction ◽  
Rate Of Reaction

Two proteins, haemoglobin and bovine serum albumin, have been studied with respect to their rates of alkylation by chlorambucil in vitro at 37 °C and pH 8.4. The proteins are of nearly the same molecular weight and free carboxylic acid content, but the alkylation reaction is 30 times faster with haemoglobin. On the other hand, the adsorption of chlorambucil by albumin is 20 times greater than that exhibited by haemoglobin. This inverse relationship between extent of adsorption and reaction rate suggests that adsorption protects the chlorambucil from activation in the solvent.

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