Experimental versus theoretical evidence for the rate-limiting steps in uncatalyzed and H+ - and HO− -catalyzed hydrolysis of the amide bond

2009 ◽  
Vol 41 (9) ◽  
pp. 599-611 ◽  
Author(s):  
M. Niyaz Khan
Keyword(s):  
Amide Bond ◽  
Theoretical Evidence ◽  
Rate Limiting ◽  
Hydrolysis Of ◽  
Experimental Versus

scholarly journals Unwanted hydrolysis or α/β-peptide bond formation: how long should the rate-limiting coupling step take?

RSC Advances ◽  
2019 ◽  
Vol 9 (53) ◽  
pp. 30720-30728 ◽  
Author(s):  
Viktória Goldschmidt Gőz ◽  
Adrienn Nagy ◽  
Viktor Farkas ◽  
Ernő Keszei ◽  
András Perczel
Keyword(s):  
Amino Acids ◽  
Bond Formation ◽  
Side Reaction ◽  
Peptide Bond ◽  
Amide Bond ◽  
Peptide Bond Formation ◽  
Active Esters ◽  
Amide Bond Formation ◽  
Rate Limiting ◽  
Hydrolysis Of

Parallel to the amide bond formation, the hydrolysis of the active esters of α/β-amino acids, as an unwanted side reaction limiting coupling efficacy, is studied.

The hydrolysis and biogas production of complex cellulosic substrates using three anaerobic biomass sources

2013 ◽  
Vol 67 (2) ◽  
pp. 293-298 ◽  
Author(s):  
C. Keating ◽  
D. Cysneiros ◽  
T. Mahony ◽  
V. O'Flaherty
Keyword(s):  
Biogas Production ◽  
Positive Role ◽  
Diverse Range ◽  
Factors Affecting ◽  
Rate Limiting Step ◽  
Solid Substrates ◽  
Different Temperatures ◽  
Anaerobic Biomass ◽  
Rate Limiting ◽  
Hydrolysis Of

In this study, the ability of various sludges to digest a diverse range of cellulose and cellulose-derived substrates was assessed at different temperatures to elucidate the factors affecting hydrolysis. For this purpose, the biogas production was monitored and the specific biogas activity (SBA) of the sludges was employed to compare the performance of three anaerobic sludges on the degradation of a variety of complex cellulose sources, across a range of temperatures. The sludge with the highest performance on complex substrates was derived from a full-scale bioreactor treating sewage at 37 °C. Hydrolysis was the rate-limiting step during the degradation of complex substrates. No activity was recorded for the synthetic cellulose compound carboxymethylcellulose (CMC) using any of the sludges tested. Increased temperature led to an increase in hydrolysis rates and thus SBA values. The non-granular nature of the mesophilic sludge played a positive role in the hydrolysis of solid substrates, while the granular sludges proved more effective on the degradation of soluble compounds.

scholarly journals Hydrolysis of Methionine- and Histidine-Containing Peptides Promoted by Dinuclear Platinum(II) Complexes with Benzodiazines as Bridging Ligands: Influence of Ligand Structure on the Catalytic Ability of Platinum(II) Complexes

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Snežana Rajković ◽  
Beata Warżajtis ◽  
Marija D. Živković ◽  
Biljana Đ. Glišić ◽  
Urszula Rychlewska ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Amide Bond ◽  
Spectroscopic Techniques ◽  
X Ray Diffraction ◽  
Bridging Ligands ◽  
Metal Centers ◽  
H Nmr ◽  
Dinuclear Platinum ◽  
Ph Range ◽  
Hydrolysis Of

Dinuclear platinum(II) complexes, [{Pt(en)Cl}2(μ-qx)]Cl2·2H2O (1), [{Pt(en)Cl}2(μ-qz)](ClO4)2(2), and [{Pt(en)Cl}2(μ-phtz)]Cl2·4H2O (3), were synthesized and characterized by different spectroscopic techniques. The crystal structure of1was determined by single-crystal X-ray diffraction analysis, while the DFT M06-2X method was applied in order to optimize the structures of1–3. The chlorido Pt(II) complexes1–3were converted into the corresponding aqua species1a–3a, and their reactions with an equimolar amount of Ac–L–Met–Gly and Ac–L–His–Gly dipeptides were studied by1H NMR spectroscopy in the pH range 2.0 < pH < 2.5 at 37°C. It was found that, in all investigated reactions with the Ac–L–Met–Gly dipeptide, the cleavage of the Met–Gly amide bond had occurred, but complexes2aand3ashowed lower catalytic activity than1a. However, in the reactions with Ac–L–His–Gly dipeptide, the hydrolysis of the amide bond involving the carboxylic group of histidine was observed only with complex1a. The observed disparity in the catalytic activity of these complexes is thought to be due to different relative positioning of nitrogen atoms in the bridging qx, qz, and phtz ligands and consequent variation in the intramolecular separation of the two platinum(II) metal centers.

scholarly journals Unexpected Resistance to Base-Catalyzed Hydrolysis of Nitrogen Pyramidal Amides Based on the 7-Azabicyclic[2.2.1]heptane Scaffold

Molecules ◽  
2018 ◽  
Vol 23 (9) ◽  
pp. 2363 ◽  
Author(s):  
Diego Ocampo Gutiérrez de Velasco ◽  
Aoze Su ◽  
Luhan Zhai ◽  
Satowa Kinoshita ◽  
Yuko Otani ◽  
...  
Keyword(s):  
Nitrogen Atom ◽  
Amide Bond ◽  
Free Energies ◽  
Amide Nitrogen ◽  
Bond Rotation ◽  
Entropy Term ◽  
And Inversion ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Amide Nitrogen Atom

Non-planar amides are usually transitional structures, that are involved in amide bond rotation and inversion of the nitrogen atom, but some ground-minimum non-planar amides have been reported. Non-planar amides are generally sensitive to water or other nucleophiles, so that the amide bond is readily cleaved. In this article, we examine the reactivity profile of the base-catalyzed hydrolysis of 7-azabicyclo[2.2.1]heptane amides, which show pyramidalization of the amide nitrogen atom, and we compare the kinetics of the base-catalyzed hydrolysis of the benzamides of 7-azabicyclo[2.2.1]heptane and related monocyclic compounds. Unexpectedly, non-planar amides based on the 7-azabicyclo[2.2.1]heptane scaffold were found to be resistant to base-catalyzed hydrolysis. The calculated Gibbs free energies were consistent with this experimental finding. The contribution of thermal corrections (entropy term, –TΔS‡) was large; the entropy term (ΔS‡) took a large negative value, indicating significant order in the transition structure, which includes solvating water molecules.

Potential of anaerobic digestion of complex waste(water)

2001 ◽  
Vol 44 (8) ◽  
pp. 115-122 ◽  
Author(s):  
G. Zeeman ◽  
W. Sanders
Keyword(s):  
Waste Water ◽  
Anaerobic Digestion ◽  
Order Relation ◽  
Organic Substrates ◽  
Reactor Technology ◽  
Rate Limiting Step ◽  
Treatment Technologies ◽  
Transport Complex ◽  
Rate Limiting ◽  
Hydrolysis Of

Although they differ greatly in origin complex waste(water)s mainly consist of proteins, lipids, carbohydrates and sometimes lignin in addition. Hydrolysis is the first and generally rate-limiting step in the process of anaerobic digestion of particulate organic substrates. Hydrolysis of particulate polymers can be described by Surface Based Kinetics, but for use in practice the empirical first order relation is advised. Unlike the hydrolysis of protein and carbohydrate, lipid hydrolysis is hardly occurring in the absence of methanogenesis. The latter is probably a physical rather than a biological process and affects the choice for either a one- or a two-step (phase) anaerobic reactor. In the chain of collection and transport, complex wastes often become complex wastewaters simply because of dilution. Dilution not only changes the reactor technology to be applied but also complicates the post-treatment and possibilities for resource recovery. Combining concentrated with diluted waste streams will almost always end up in much more complicated treatment technologies.

Biological treatability of a corn wet mill effluent

2002 ◽  
Vol 45 (12) ◽  
pp. 339-346 ◽  
Author(s):  
G. Eremektar ◽  
O. Karahan-Gul ◽  
F. Germirli-Babuna ◽  
S. Ovez ◽  
H. Uner ◽  
...  
Keyword(s):  
Biological Treatment ◽  
Rate Coefficient ◽  
Activated Sludge Process ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Metabolic Products ◽  
High Level ◽  
Biological Treatability ◽  
Rate Limiting ◽  
Hydrolysis Of

Corn wet mill effluents are studied in terms of their characteristics relevant for biological treatment. They have a high COD of mainly soluble and biodegradable nature, with practically no soluble inert components. They generate a relatively high level of soluble residual metabolic products, which affects the choice of the appropriate biological treatment and favors aerobic activated sludge process. Experimental assessment of process kinetics yields typical values. Hydrolysis of the slowly biodegradable COD, the rate limiting step for the utilization of substrate, is characterized by an overall rate coefficient, which is within the range commonly associated for the hydrolysis of starch.

Water-Promoted Hydrolysis of a Highly Twisted Amide:  Rate Acceleration Caused by the Twist of the Amide Bond

2005 ◽  
Vol 127 (12) ◽  
pp. 4445-4453 ◽  
Author(s):  
Jon Iñaki Mujika ◽  
Jose Maria Mercero ◽  
Xabier Lopez
Keyword(s):  
Amide Bond ◽  
Rate Acceleration ◽  
Hydrolysis Of
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