scholarly journals Electrostatic compared with hydrophobic interactions between bovine serum amine oxidase and its substrates

2003 ◽  
Vol 371 (2) ◽  
pp. 549-556 ◽  
Author(s):  
Maria Luisa DI PAOLO ◽  
Roberto STEVANATO ◽  
Alessandra CORAZZA ◽  
Fabio VIANELLO ◽  
Lorenzo LUNELLI ◽  
...  
Keyword(s):  
Active Site ◽  
Bovine Serum ◽  
Hydrophobic Interactions ◽  
Amine Oxidase ◽  
Amino Acid Residues ◽  
Deprotonated Form ◽  
Steady State Kinetic ◽  
Wide Range ◽  
Order Of Magnitude

A steady-state kinetic study of bovine serum amine oxidase activity was performed, over a wide range of pH values (5.4–10.2) and ionic strength (10–200mM), using various (physiological and analogue) substrates as specific probes of the active-site binding region. Relatively small changes in kcat values (approx. one order of magnitude) accompanied by marked changes in Km and kcat/Km values (approx. six orders of magnitude) were observed. This behaviour was correlated with the presence of positively charged groups or apolar chains in the substrates. In particular, it was found that the docking of the physiological polyamines, i.e. spermidine and spermine, appears to be modulated by three amino acid residues of the active site, which we have named L-H+, G-H+ and IH+, characterized by pKa values of 6.2±0.2 [Di Paolo, Scarpa, Corazza, Stevanato and Rigo (2002) Biophys. J. 83, 2231–2239], 8.2±0.3 and 7.8±0.4 respectively. The electrostatic interaction between the protonated substrates and the enzyme containing the residues L-H+, G-H+ and IH+ in the deprotonated form, the on/off role of the IH+ residue and the role of hydrophobic interactions with substrates characterized by apolar chains are discussed.

N-alkanamines as substrates to probe the hydrophobic region of bovine serum amine oxidase active site: A kinetic and spectroscopic study

2007 ◽  
Vol 465 (1) ◽  
pp. 50-60 ◽  
Author(s):  
Maria Luisa Di Paolo ◽  
Carmine Pesce ◽  
Michele Lunelli ◽  
Marina Scarpa ◽  
Adelio Rigo
Keyword(s):  
Spectroscopic Study ◽  
Active Site ◽  
Bovine Serum ◽  
Amine Oxidase ◽  
Hydrophobic Region

The role of copper in bovine serum amine oxidase

1990 ◽  
Vol 3 (2) ◽  
pp. 114-117 ◽  
Author(s):  
Laura Morpurgo ◽  
Enzo Agostinelli ◽  
Bruno Mondov� ◽  
Luciana Avigliano
Keyword(s):  
Bovine Serum ◽  
Amine Oxidase

The role of surface cohesion is wind-driven snow transport

2020 ◽  
Author(s):  
Francesco Comola ◽  
Johan Gaume ◽  
Jasper Kok ◽  
Michael Lehning
Keyword(s):  
Blowing Snow ◽  
Snow Surface ◽  
Wind Speeds ◽  
Wide Range ◽  
Bed Forms ◽  
Geophysical Processes ◽  
Order Of Magnitude ◽  
History Of ◽  
Snow Transport

<p>The wind-driven saltation of sediments, such as snow and sand, is responsible for a wide range of geophysical processes. Blowing-snow, in particular, affects snow surface properties and drives snow redistribution in alpine terrain. As such, it is of fundamental importance for avalanche mechanics. One of the most important controls on initiation and development of snow saltation is the surface cohesion induced by ice particle sintering. Although inter-particle cohesion is known to limit the number of grains lifted from the surface through aerodynamic entrainment and granular splash, the role of cohesion in the development of saltation from onset to steady state is still poorly understood. Using a numerical model based on the discrete element method, we show that saltation over cohesive beds sustains itself at wind speeds one order of magnitude smaller than those necessary to initiate it, giving rise to hysteresis in which the occurrence of transport depends on the history of the wind. Our results further suggest that saltation over cohesive beds requires much longer distances to saturate, thereby increasing the size of the smallest stable bed forms.</p>

scholarly journals Structural and Mutagenic Analysis of Metallo-β-Lactamase IMP-18

2016 ◽  
Vol 60 (9) ◽  
pp. 5521-5526 ◽  
Author(s):  
Takamitsu Furuyama ◽  
Haruka Nonomura ◽  
Yoshikazu Ishii ◽  
Nancy D. Hanson ◽  
Akiko Shimizu-Ibuka
Keyword(s):  
Crystal Structure ◽  
Active Site ◽  
Kinetic Properties ◽  
Amino Acid Residues ◽  
Content Type ◽  
Zinc Metalloenzymes ◽  
Order Of Magnitude ◽  
Sandwich Configuration ◽  
The Relationship ◽  
Loop Conformation

ABSTRACTIMP-type metallo-β-lactamases (MBLs) are exogenous zinc metalloenzymes that hydrolyze a broad range of β-lactams, including carbapenems. Here we report the crystal structure of IMP-18, an MBL cloned fromPseudomonas aeruginosa, at 2.0-Å resolution. The overall structure of IMP-18 resembles that of IMP-1, with an αβ/βα “folded sandwich” configuration, but the loop that covers the active site has a distinct conformation. The relationship between IMP-18's loop conformation and its kinetic properties was investigated by replacing the amino acid residues that can affect the loop conformation (Lys44, Thr50, and Ile69) in IMP-18 with those occupying the corresponding positions in the well-described enzyme IMP-1. The replacement of Thr50 with Pro considerably modified IMP-18's kinetic properties, specifically those pertaining to meropenem, with thekcat/Kmvalue increased by an order of magnitude. The results indicate that this is a key residue that defines the kinetic properties of IMP-type β-lactamases.

scholarly journals Reconstitution of Cu2+-depleted bovine serum amine oxidase with Co2+*

1998 ◽  
Vol 330 (1) ◽  
pp. 383-387 ◽  
Author(s):  
Enzo AGOSTINELLI ◽  
Giovanna DE MATTEIS ◽  
Bruno MONDOVÌ ◽  
Laura MORPURGO
Keyword(s):  
Active Site ◽  
Bovine Serum ◽  
Oxidase Activity ◽  
Amine Oxidase ◽  
Semiquinone Radical ◽  
Copper Site ◽  
Benzylamine Oxidase ◽  
Topa Quinone ◽  
Derivatives Of ◽  
Active Subunits

Two different Cu2+-depleted derivatives of bovine serum amine oxidase (BSAO) have recently been prepared, which contain about 0.5 mol/dimer of phenylhydrazine-reactive topa quinone (TPQ) cofactor and, depending on the reagents used, about 0.2 or 0.7 residual Cu2+/dimer [Agostinelli, De Matteis, Sinibaldi, Mondovì and Morpurgo (1997) Biochem. J. 324, 497-501]. The benzylamine oxidase activity of both derivatives was < 5% and increased up to ≈ 20% on incorporation of Co2+, irrespective of the residual Cu2+ content, which was unaffected by the treatment according to atomic absorption and ESR spectroscopy. The residual Cu2+ ions appeared to be distributed one per dimer and to be bound to inactive subunits, whereas Co2+ was bound to active subunits. The change in the active site had an appreciable influence on the kinetic behaviour. With several amines, the kinetic parameters, Km and kc, measured for Co2+-BSAO were different from those for native BSAO. This excludes the possibility that the catalytic activity was due to residual Cu2+. Furthermore, Co2+ restored to nearly native level the intensity of the TPQ 480 nm band and the reactions with phenylhydrazine or benzylhydrazine, which had been slowed down or abolished, respectively, in Cu2+-depleted samples. The CD spectrum, measured for the derivative with low Cu2+ content, was compatible with Co2+ binding to the copper site. The amine oxidase activity of the Co2+ derivative, which cannot form a semiquinone radical as an intermediate of the catalytic reaction, strongly suggests that the Cu+-semiquinone is not an obligatory intermediate of BSAO catalytic pathway.

scholarly journals Exploring the Role of Phenylalanine Residues in Modulating the Flexibility and Topography of the Active Site in the Peroxygenase Variant PaDa-I

2020 ◽  
Vol 21 (16) ◽  
pp. 5734
Author(s):  
Joaquin Ramirez-Ramirez ◽  
Javier Martin-Diaz ◽  
Nina Pastor ◽  
Miguel Alcalde ◽  
Marcela Ayala
Keyword(s):  
Hydrogen Peroxide ◽  
Cytochrome P450 ◽  
Active Site ◽  
Bulk Solution ◽  
Computational Studies ◽  
Organic Substrates ◽  
Oxidation Reactions ◽  
Heme Group ◽  
Wide Range

Unspecific peroxygenases (UPOs) are fungal heme-thiolate enzymes able to catalyze a wide range of oxidation reactions, such as peroxidase-like, catalase-like, haloperoxidase-like, and, most interestingly, cytochrome P450-like. One of the most outstanding properties of these enzymes is the ability to catalyze the oxidation a wide range of organic substrates (both aromatic and aliphatic) through cytochrome P450-like reactions (the so-called peroxygenase activity), which involves the insertion of an oxygen atom from hydrogen peroxide. To catalyze this reaction, the substrate must access a channel connecting the bulk solution to the heme group. The composition, shape, and flexibility of this channel surely modulate the catalytic ability of the enzymes in this family. In order to gain an understanding of the role of the residues comprising the channel, mutants derived from PaDa-I, a laboratory-evolved UPO variant from Agrocybe aegerita, were obtained. The two phenylalanine residues at the surface of the channel, which regulate the traffic towards the heme active site, were mutated by less bulky residues (alanine and leucine). The mutants were experimentally characterized, and computational studies (i.e., molecular dynamics (MD)) were performed. The results suggest that these residues are necessary to reduce the flexibility of the region and maintain the topography of the channel.

scholarly journals Structural Insights into the Subclass B3 Metallo-β-Lactamase SMB-1 and the Mode of Inhibition by the Common Metallo-β-Lactamase Inhibitor Mercaptoacetate

2012 ◽  
Vol 57 (1) ◽  
pp. 101-109 ◽  
Author(s):  
Jun-ichi Wachino ◽  
Yoshihiro Yamaguchi ◽  
Shigetarou Mori ◽  
Hiromasa Kurosaki ◽  
Yoshichika Arakawa ◽  
...  
Keyword(s):  
Amino Acid ◽  
Active Site ◽  
Hydrolytic Activity ◽  
The Other ◽  
Amino Acid Residues ◽  
Hydrogen Bond Interaction ◽  
Content Type ◽  
Carboxylate Oxygen ◽  
Wide Range ◽  
Environmental Bacteria

ABSTRACTA novel subclass B3 metallo-β-lactamase (MBL), SMB-1, recently identified from aSerratia marcescensclinical isolate, showed a higher hydrolytic activity against a wide range of β-lactams than did the other subclass B3 MBLs, i.e., BJP-1 and FEZ-1, from environmental bacteria. To identify the mechanism underlying the differences in substrate specificity among the subclass B3 MBLs, we determined the structure of SMB-1, using 1.6-Å diffraction data. Consequently, we found that SMB-1 reserves a space in the active site to accommodate β-lactam, even with a bulky R1 side chain, due to a loss of amino acid residues corresponding to F31 and L226 of BJP-1, which protrude into the active site to prevent β-lactam from binding. The protein also possesses a unique amino acid residue, Q157, which probably plays a role in recognition of β-lactams via the hydrogen bond interaction, which is missing in BJP-1 and FEZ-1, whoseKmvalues for β-lactams are particularly high. In addition, we determined the mercaptoacetate (MCR)-complexed SMB-1 structure and revealed the mode of its inhibition by MCR: the thiolate group bridges to two zinc ions (Zn1 and Zn2). One of the carboxylate oxygen atoms of MCR makes contact with Zn2 and Ser221, and the other makes contact with T223 and a water molecule. Our results demonstrate the possibility that MCR could be a potent inhibitor for subclass B3 MBLs and that the screening technique using MCR as an inhibitor would be effective for detecting subclass B3 MBL producers.

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