scholarly journals Spectroscopic Definition of a Highly Reactive Site in Cu-CHA for Selective Methane Oxidation: Tuning a Mono-μ-Oxo Dicopper(II) Active Site for Reactivity

2021 ◽  
Author(s):  
Hannah M. Rhoda ◽  
Dieter Plessers ◽  
Alexander J. Heyer ◽  
Max L. Bols ◽  
Robert A. Schoonheydt ◽  
...  
Keyword(s):  
Methane Oxidation ◽  
Active Site ◽  
Reactive Site ◽  
Definition Of

scholarly journals Structural comparisons lead to the definition of a new superfamily of NAD(P)(H)-accepting oxidoreductases: the single-domain reductases/epimerases/dehydrogenases (the ‘RED’ family)

1994 ◽  
Vol 304 (1) ◽  
pp. 95-99 ◽  
Author(s):  
G Labesse ◽  
A Vidal-Cros ◽  
J Chomilier ◽  
M Gaudry ◽  
J P Mornon
Keyword(s):  
Amino Acids ◽  
Sequence Alignment ◽  
Active Site ◽  
Tertiary Structure ◽  
Binding Specificity ◽  
Single Domain ◽  
Divergent Evolution ◽  
Cofactor Binding ◽  
Sequence Identity ◽  
Definition Of

Using both primary- and tertiary-structure comparisons, we have established new structural similarities shared by reductases, epimerases and dehydrogenases not previously known to be related. Despite the low sequence identity (down to 10%), short consensus segments are identified. We show that the sequence, the active site and the supersecondary structure are well conserved in these proteins. New homologues (the protochlorophyllide reductases) are detected, and we define a new superfamily composed of single-domain dinucleotide-binding enzymes. Rules for the cofactor-binding specificity are deduced from our sequence alignment. The involvement of some amino acids in catalysis is discussed. Comparison with two-domain dehydrogenases allows us to distinguish two general mechanisms of divergent evolution.

CHARACTERIZATION OFα2-ANTIPLASMIN.REACTIVE SITE VARIANTS PRODUCED BY SITE-DIRECTED MUTAGENESIS

1987 ◽  
Author(s):  
W E Holmes ◽  
H R Lijnen ◽  
D Collen
Keyword(s):  
Sequence Analysis ◽  
Complex Formation ◽  
Active Site ◽  
Activity Analysis ◽  
Site Directed Mutagenesis ◽  
Thrombin Inhibitor ◽  
Directed Mutagenesis ◽  
Reactive Site ◽  
Antithrombin Activity ◽  
Bovine Trypsin

α2-Antiplasmin (α2AP) is the primary physiological plasmin inhibitor in human plasma. The inhibition is rapid (second order rate constants (k1) are expressed as M−1 s−1 ) (k1 = 2 × 107) and occurs as the consequence of an irreversible 1:1 stoichiometric complex formation; the exact nature of and the forces involved in complex formation are not fully understood. In fact, what makes α2AP an inhibitor, rather than simply a substrate remains unresolved. Recently, we deduced the primary structure of α2 AP from the sequence of its cDNA. 95%of this sequence was confirmed by amino acid (aa) sequence analysis of naturalα2 AP (α2 AP)? The 452 aa molecule contains 2 disulfide bonds and 4 glycosylated Asn residues, aa sequence alignment confirmed α2AP's membership in the Serpin family. The reactive site sequence as determined by NH2 - and COOH-terminal aa sequence analysis of the plasmin-modified inhibitor and the released M−r ∼ 8000 peptide is Met362-Ser363-Arg364-Met365-Ser366, P3-P2-P1-P'1-P'2, respectively.Natural and engineered P1 residue substitutions in the Serpin α2 -antitrypsin ( α2 AT) have shown altered specificities and efficiencies. To further examine the role of P and P' residues in determining Serpin specificity, in the present study we have by site-directed mutagenesis, deleted (△) the P'l-Met365 residue of a AP thereby producing a recombinant (r) inhibitor (r α2 AP△Met365) whose putative new reactive site mimics that of antithrombin III (ATIII) and a AT-Pittsburgh (Pl-Arg-P'1-Ser). A second variant was constructed (ra2AP△Arg364) in which the Pl-Arg364 residue was deleted, producing the new sequence Met362-Ser363-Met364-Ser365, containing 2 potential sites analogous to the Pl-P'l, Met-Ser reactive site of α2 AT. The variants and r α2 AP were expressed in CH0 cells, purified and compared with n α2 AP, α2AT and ATIII for the ability to inhibit plasmin, thrombin, trypsin and elastase. n α2 AP and r α2 AP had nearly identical inhibition constants and like ATIII did not inhibit neutrophil elastase. Without heparin both α2 APs and ATIII inhibited thrombin moderately (k1 = 2 to 4× 103 ). Bovine trypsin was neutralized by the α2 APs with k1 = 3 × 106 and by ATIII with k1 = 1 × 105. The α2APs inhibited plasmin (k1 = 2 ×107 ) much more efficiently than ATIII (K1 =2 × 103 ). In contrast, was a highly effective antielastase (k1 = 1 × 107 ), a poor plasmin and thrombin inhibitor ancl inhibited bovine trypsin with = 2 × 10. As reported by others, α2 AT-Pittsburg has greatly reduced antielastase activity and greatly enhanced antithrombin activity. Analysis of ra APAMet365 revealed little change in activity toward plasmin, trypsin and elastase. Thus, α2 AP has no absolute requirement for Met .in the P'l position in order to effectively inhibit plasmin and trypsin. The other P^ subsites appear to be spatially flexible as deletion of the natural P'l residue must displace them. Contrary to prediction a 20-fold decrease in antithrombin activity was observed rather than an enhanced activity. Analysis of rα2 AP△Arg364 showed that it is unreactive with plasmin, trypsin and thrombin, but that it has acquired a significant antielastase activity (k1 = 1.5 × 105). The exact PI residue(s) has not been determined but removal of the bulky basic Arg364 may have resulted in accessibility of the predicted reactive site(s) peptide bond(s) Met362-Ser363 or Met364-Ser365 to the active site cleft of elastase. α2AP'Enschede', a natural mutant with deficient antiplasmin activity, was shown to contain an Ala insertion between aa 353 and 357, 7 to 10 positions NH2-terminal to its reactive site (Holmes et al., this meeting). This mutation results in conversion of α2 AP'Enschede' from an inhibitor to a substrate that retains a high affinity for the active site of plasmin.

Cover Picture: From Active‐Site Models to Real Catalysts: Importance of the Material Gap in the Design of Pd Catalysts for Methane Oxidation (ChemCatChem 9/2017)

ChemCatChem ◽  
2017 ◽  
Vol 9 (9) ◽  
pp. 1518-1518
Author(s):  
Hieu A. Doan ◽  
Munish K. Sharma ◽  
William S. Epling ◽  
Lars C. Grabow
Keyword(s):  
Methane Oxidation ◽  
Active Site ◽  
Pd Catalysts

Spectroscopic Definition of the Copper Active Sites in Mordenite: Selective Methane Oxidation

2015 ◽  
Vol 137 (19) ◽  
pp. 6383-6392 ◽  
Author(s):  
Pieter Vanelderen ◽  
Benjamin E. R. Snyder ◽  
Ming-Li Tsai ◽  
Ryan G. Hadt ◽  
Julie Vancauwenbergh ◽  
...  
Keyword(s):  
Methane Oxidation ◽  
Active Sites ◽  
Definition Of

scholarly journals Metal substitution of tetanus neurotoxin

1997 ◽  
Vol 322 (2) ◽  
pp. 507-510 ◽  
Author(s):  
Fiorella TONELLO ◽  
Giampietro SCHIAVO ◽  
Cesare MONTECUCCO
Keyword(s):  
Active Site ◽  
Transition Metal Ions ◽  
Structural Basis ◽  
Metal Substitution ◽  
Absorbance Spectrum ◽  
Independent Family ◽  
Tetanus Neurotoxin ◽  
Highly Active ◽  
Clostridial Neurotoxins ◽  
Definition Of

Tetanus neurotoxin was depleted of its catalytic Zn2+ ion, and the apotoxin was reconstituted with different transition metal ions. The Mn2+- and Co2+-tetanus neurotoxins are highly active in the proteolysis of vesicle-associated membrane protein/synaptobrevin, the natural substrate of this toxin, whereas Cu2+ and Fe2+ minimally supported proteolytic activity. The visible absorbance spectrum of Co2+-tetanus neurotoxin shows a maximum at 538 nm with a molar absorption coefficient of 82 M-1·cm-1. These results indicate that the Zn2+ environment at the active site of tetanus neurotoxin is different from those of known Zn2+-endopeptidases and provide a structural basis for the definition of tetanus neurotoxin, and the related clostridial neurotoxins, as an independent family of metalloproteases.

scholarly journals From Active‐Site Models to Real Catalysts: Importance of the Material Gap in the Design of Pd Catalysts for Methane Oxidation

ChemCatChem ◽  
2017 ◽  
Vol 9 (9) ◽  
pp. 1520-1520
Author(s):  
Hieu A. Doan ◽  
Munish K. Sharma ◽  
William S. Epling ◽  
Lars C. Grabow
Keyword(s):  
Methane Oxidation ◽  
Active Site ◽  
Pd Catalysts

Mapping of Human Plasma Kallikrein Active Site by Design of Peptides Based on Modifications of a Kazal-Type Inhibitor Reactive Site

2003 ◽  
Vol 22 (6) ◽  
pp. 533-541 ◽  
Author(s):  
V. A. Nunes ◽  
A. J. Gozzo ◽  
M. U. Sampaio ◽  
M. A. Juliano ◽  
C. A. M. Sampaio ◽  
...  
Keyword(s):  
Human Plasma ◽  
Active Site ◽  
Plasma Kallikrein ◽  
Reactive Site

Spectroscopic definition of the non-heme iron active site in bleomycin

1995 ◽  
Vol 59 (2-3) ◽  
pp. 365
Author(s):  
Kelly E. Loeb ◽  
Jeffrey M. Zaleski ◽  
Tami E. Westre ◽  
Richard J. Guajardo ◽  
Pradip K. Mascharak ◽  
...  
Keyword(s):  
Active Site ◽  
Heme Iron ◽  
Non Heme Iron ◽  
Definition Of

scholarly journals Monocopper Active Site for Partial Methane Oxidation in Cu-Exchanged 8MR Zeolites

ACS Catalysis ◽  
2016 ◽  
Vol 6 (10) ◽  
pp. 6531-6536 ◽  
Author(s):  
Ambarish R. Kulkarni ◽  
Zhi-Jian Zhao ◽  
Samira Siahrostami ◽  
Jens K Nørskov ◽  
Felix Studt
Keyword(s):  
Methane Oxidation ◽  
Active Site ◽  
Partial Methane Oxidation
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