The contribution of the active-site residue, Y89, to the trillion-fold acceleration of Co-carbon bond homolysis rate in the methylmalonyl-CoA mutase-catalyzed reaction has been evaluated by site-directed mutagenesis. Conversion of Y89 to phenylalanine or alanine results in a 10(3)-fold diminution of k(cat) and suppression of the overall kinetic isotope effect. The spectrum of the enzyme under steady-state conditions reveals the presence of AdoCbl but no cob(II)alamin. Together, these results are consistent with homolysis becoming completely rate determining in the forward direction in the two mutants and points to the role of Y89 as a molecular wedge in accelerating Co-carbon bond cleavage.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1021/ja029420+ | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
In mammals, cobalamin is an essential cofactor that is delivered by a multitude of chaperones in an elaborate trafficking pathway to two client enzymes, methionine synthase and methylmalonyl-CoA mutase (MMUT). Rhodibalamins, the rhodium analogs of cobalamins, have been described as antimetabolites due to their ability to inhibit bacterial growth. In this study, we have examined the reactivity of adenosylrhodibalamin (AdoRhbl) with two key human chaperones, MMACHC (also known as CblC) and adenosyltransferase (MMAB, also known as ATR), and with the human and MMUT.
View Article and Find Full Text PDFDiesel soot combustion in air-NO environment: Evolution of functional groups on soot surfaces.
Sci Total Environ
March 2024
School of Automotive and Transportation Engineering, Hefei University of Technology, No. 93 Tunxi Road, Hefei 230009, China. Electronic address:
It is inevitable for NO to be involved in the soot combustion in diesel particulate filters (DPFs), so giving full play to the NO oxidation activity is one of the most effective means to improve the DPF regeneration performance. In this work, based on the results of programmed temperature oxidation (TPO) experiments, Fourier transfer inference spectroscopy, and X-ray photoelectron spectroscopy, the evolution of surface functional groups was seriously analyzed to explore the soot oxidation mechanism. The results revealed that with the presence of NO in the air atmosphere, the concentration of -ONO groups showed an increasing trend in the early oxidation stage of 0-20 % oxidation degree (OD) and then slowly decreased during 20-80 % OD, while the variations in CH functional group concentration were directly related to the concentration NO in the air atmosphere.
View Article and Find Full Text PDFBiodegradation of polyester polyurethane by Cladosporium sp. P7: Evaluating its degradation capacity and metabolic pathways.
J Hazard Mater
April 2023
Key Laboratory for Waste Plastics Biocatalytic Degradation and Recycling, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211800, PR China; State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing 211800, PR China.
Microorganisms capable of decomposing polyurethane (PU) and other plastics have the potential to be used in bio-recycling processes. In this study, 20 PU-degrading strains were isolated, including 11 bacteria and 9 fungi, using a synthesized poly(1,4-butylene adipate)-based PU (PBA-PU) as the screening substrate. Three PU substrates with increasing structure complexities were used for a thorough evaluation of microbial degradation capacity: Impranil® DLN-SD, PBA-PU film and PU foam waste.
View Article and Find Full Text PDFReductive defluorination of perfluorooctanoic acid by titanium(III) citrate with vitamin B and copper nanoparticles.
J Hazard Mater
October 2017
Research Center for Environmental Pollution Prevention and Control Technology, Graduate Institute of Environmental Engineering, National Taiwan University, 71, Chou-Shan Rd., Taipei 106, Taiwan, ROC. Electronic address:
Perfluorooctanoic acid (PFOA) is widespread in the environment, which causes serious health and safety concerns. A mechanistic study on reductive defluorination of PFOA by titanium(III) citrate in the presence of catalysts was conducted. Vitamin B was used to catalyze reduction reactions by shuttling electrons from a reducing agent (electron donor) to PFOA to produce a Co-carbon bond intermediates.
View Article and Find Full Text PDFSelective Aliphatic Carbon-Carbon Bond Activation by Rhodium Porphyrin Complexes.
Acc Chem Res
July 2017
Department of Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, People's Republic of China.
The carbon-carbon bond activation of organic molecules with transition metal complexes is an attractive transformation. These reactions form transition metal-carbon bonded intermediates, which contribute to fundamental understanding in organometallic chemistry. Alternatively, the metal-carbon bond in these intermediates can be further functionalized to construct new carbon-(hetero)atom bonds.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!