scholarly journals A Single Active-Site Mutation of P450BM-3 Dramatically Enhances Substrate Binding and Rate of Product Formation

Biochemistry ◽  
2011 ◽  
Vol 50 (39) ◽  
pp. 8333-8341 ◽  
Author(s):  
Donovan C. Haines ◽  
Amita Hegde ◽  
Baozhi Chen ◽  
Weiqiang Zhao ◽  
Muralidhar Bondlela ◽  
...  
Keyword(s):  
Active Site ◽  
Substrate Binding ◽  
Product Formation ◽  
Site Mutation

Insights into the roles of charged residues in substrate binding and mode of action of mannuronan C-5 epimerase AlgE4

Glycobiology ◽  
2021 ◽  
Author(s):  
Margrethe Gaardløs ◽  
Sergey A Samsonov ◽  
Marit Sletmoen ◽  
Maya Hjørnevik ◽  
Gerd Inger Sætrom ◽  
...  
Keyword(s):  
Optical Tweezers ◽  
Conformational Changes ◽  
Molecular Mechanisms ◽  
Hydrophobic Interactions ◽  
Substrate Binding ◽  
Interdisciplinary Approach ◽  
Product Formation ◽  
Titration Calorimetry ◽  
Binding Groove ◽  
Dynamics Simulations

Abstract Mannuronan C-5 epimerases catalyse the epimerization of monomer residues in the polysaccharide alginate, changing the physical properties of the biopolymer. The enzymes are utilized to tailor alginate to numerous biological functions by alginate-producing organisms. The underlying molecular mechanisms that control the processive movement of the epimerase along the substrate chain is still elusive. To study this, we have used an interdisciplinary approach combining molecular dynamics simulations with experimental methods from mutant studies of AlgE4, where initial epimerase activity and product formation were addressed with NMR spectroscopy, and characteristics of enzyme-substrate interactions were obtained with isothermal titration calorimetry and optical tweezers. Positive charges lining the substrate-binding groove of AlgE4 appear to control the initial binding of poly-mannuronate, and binding also seems to be mediated by both electrostatic and hydrophobic interactions. After the catalytic reaction, negatively charged enzyme residues might facilitate dissociation of alginate from the positive residues, working like electrostatic switches, allowing the substrate to translocate in the binding groove. Molecular simulations show translocation increments of two monosaccharide units before the next productive binding event resulting in MG-block formation, with the epimerase moving with its N-terminus towards the reducing end of the alginate chain. Our results indicate that the charge pair R343-D345 might be directly involved in conformational changes of a loop that can be important for binding and dissociation. The computational and experimental approaches used in this study complement each other, allowing for a better understanding of individual residues’ roles in binding and movement along the alginate chains.

Non-oxidative dehydrogenation of propane, n-butane, and isobutane over bulk ZrO2-based catalysts: effect of dopant on the active site and pathways of product formation

2017 ◽  
Vol 7 (19) ◽  
pp. 4499-4510 ◽  
Author(s):  
Tatiana P. Otroshchenko ◽  
Vita A. Kondratenko ◽  
Uwe Rodemerck ◽  
David Linke ◽  
Evgenii V. Kondratenko
Keyword(s):  
Oxidative Dehydrogenation ◽  
Active Site ◽  
Product Formation ◽  
Oxidative Dehydrogenation Of Propane

Non-oxidative dehydrogenation (DH) of propane, n-butane, and isobutane was investigated over bare ZrO2 and binary MZrOx (M = Li, Ca, Mg, Y, Sm or La) materials.

Substrate-binding specificity of chitinase and chitosanase as revealed by active-site architecture analysis

2015 ◽  
Vol 418 ◽  
pp. 50-56 ◽  
Author(s):  
Shijia Liu ◽  
Shangjin Shao ◽  
Linlin Li ◽  
Zhi Cheng ◽  
Li Tian ◽  
...  
Keyword(s):  
Active Site ◽  
Substrate Binding ◽  
Binding Specificity ◽  
Architecture Analysis

scholarly journals 1P-121 Roles of Asp297 in the vicinity of the active site of cytochrome P450cam in substrate binding(The 46th Annual Meeting of the Biophysical Society of Japan)

2008 ◽  
Vol 48 (supplement) ◽  
pp. S40
Author(s):  
Keisuke Sakurai ◽  
Katsuyoshi Harada ◽  
Kunitoshi Shimokata ◽  
Takashi Hayashi ◽  
Hideo Shimada
Keyword(s):  
Annual Meeting ◽  
Active Site ◽  
Substrate Binding ◽  
Cytochrome P450cam ◽  
Biophysical Society

scholarly journals A crystallographic study of the Toho-1 β-lactamase acylation mechanism

2014 ◽  
Vol 70 (a1) ◽  
pp. C1207-C1207
Author(s):  
Leighton Coates
Keyword(s):  
Hydrogen Bonding ◽  
Transition State ◽  
Active Site ◽  
Catalytic Mechanism ◽  
Substrate Binding ◽  
Ligand Complex ◽  
Transition State Analog ◽  
Hydrogen Bonding Interactions ◽  
Active Site Region ◽  
Neutron Crystallography

β-lactam antibiotics have been used effectively over several decades against many types of highly virulent bacteria. The predominant cause of resistance to these antibiotics in Gram-negative bacterial pathogens is the production of serine β-lactamase enzymes. A key aspect of the class A serine β-lactamase mechanism that remains unresolved and controversial is the identity of the residue acting as the catalytic base during the acylation reaction. Multiple mechanisms have been proposed for the formation of the acyl-enzyme intermediate that are predicated on understanding the protonation states and hydrogen-bonding interactions among the important residues involved in substrate binding and catalysis of these enzymes. For resolving a controversy of this nature surrounding the catalytic mechanism, neutron crystallography is a powerful complement to X-ray crystallography that can explicitly determine the location of deuterium atoms in proteins, thereby directly revealing the hydrogen-bonding interactions of important amino acid residues. Neutron crystallography was used to unambiguously reveal the ground-state active site protonation states and the resulting hydrogen-bonding network in two ligand-free Toho-1 β-lactamase mutants which provided remarkably clear pictures of the active site region prior to substrate binding and subsequent acylation [1,2] and an acylation transition-state analog, benzothiophene-2-boronic acid (BZB), which was also isotopically enriched with 11B. The neutron structure revealed the locations of all deuterium atoms in the active site region and clearly indicated that Glu166 is protonated in the BZB transition-state analog complex. As a result, the complete hydrogen-bonding pathway throughout the active site region could then deduced for this protein-ligand complex that mimics the acylation tetrahedral intermediate [3].

scholarly journals Structure of the human heterotetrameric cis-prenyltransferase complex

2020 ◽  
Author(s):  
Michal Lisnyansky Bar-El ◽  
Pavla Vankova ◽  
Petr Man ◽  
Yoni Haitin ◽  
Moshe Giladi
Keyword(s):  
Crystal Structure ◽  
Active Site ◽  
Substrate Binding ◽  
Synthesis Mechanism ◽  
Allosteric Communication ◽  
Pt Complex ◽  
C Terminus ◽  
Length Determination ◽  
Enzymatic Complex

AbstractThe human cis-prenyltransferase (hcis-PT) is an enzymatic complex essential for protein N-glycosylation. Synthesizing the precursor of the glycosyl carrier dolichol-phosphate, we reveal here that hcis-PT exhibits a novel heterotetrameric assembly in solution, composed of two catalytic dehydrodolichyl diphosphate synthase (DHDDS) and two inactive Nogo-B receptor (NgBR) subunits. The 2.3 Å crystal structure of the complex exposes a dimer-of-heterodimers arrangement, with DHDDS C-termini serving as homotypic assembly domains. Furthermore, the structure elucidates the molecular details associated with substrate binding, catalysis, and product length determination. Importantly, the distal C-terminus of NgBR transverses across the heterodimeric interface, directly participating in substrate binding and underlying the allosteric communication between the subunits. Finally, mapping disease-associated hcis-PT mutations involved in blindness, neurological and glycosylation disorders onto the structure reveals their clustering around the active site. Together, our structure of the hcis-PT complex unveils the dolichol synthesis mechanism and its perturbation in disease.

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