scholarly journals Differences in the protein fluorecence of the two iron(III)-binding sites of ovotransferrin

1975 ◽  
Vol 145 (2) ◽  
pp. 201-207 ◽  
Author(s):  
R W Evans ◽  
J J Holbrook
Keyword(s):  
Metal Binding ◽  
Binding Sites ◽  
Electronic Excitation ◽  
Tryptophan Fluorescence ◽  
Electronic Excitation Energy ◽  
Visible Absorption Spectrum ◽  
Protein Fluorescence ◽  
Visible Absorption ◽  
Metal Binding Sites ◽  
Stable Hybrid

1. Changes in the tryptophan fluorescence and the visible absorption spectrum resulting from the combination of apo-ovotransferrin with Fe3+, F,E2+, Cu2+, Zn2+, Mn2+, and Cd2+were measured. 2. As expected for a radiationless transfer of electronic excitation energy, only the ions Fe3+, Fe2+and Cu2+, which gave complexes with large extinctions between 300 and 370nm, resulted in large decreases in trytophan fluorescence. 3. The decrease in protein fluorescence was non-linear with increasing occupancy of the Fe3+ -and Cu2+ - binding sites. The decrease in fluorescence on binding of Fe3+ was biphasic and showed that the two metal-binding sites were being occupied sequentially at pH7.4-8.4. The first site reacted with Fe3+ instantaneously, the second was occupied over a minute. 5. The nonidentity of the two sites was also demonstrated by the preparation of a stable hybrid containing both Cu2+ and Zn2+.h Cu2+ and Zn2+

scholarly journals Investigation of the nature of the two metal-binding sites in 5-aminolaevulinic acid dehydratase from Escherichia coli

1994 ◽  
Vol 300 (2) ◽  
pp. 373-381 ◽  
Author(s):  
P Spencer ◽  
P M Jordan
Keyword(s):  
Escherichia Coli ◽  
Metal Ions ◽  
Metal Binding ◽  
Binding Sites ◽  
Metal Ion ◽  
Protein Fluorescence ◽  
Metal Binding Sites ◽  
Aminolaevulinic Acid ◽  
Acid Dehydratase ◽  
Aminolaevulinic Acid Dehydratase

Two distinct metal-binding sites, termed alpha and beta, have been characterized in 5-aminolaevulinic acid dehydratase from Escherichia coli. The alpha-site binds a Zn2+ ion that is essential for catalytic activity. This site can also utilize other metal ions able to function as a Lewis acid in the reaction mechanism, such as Mg2+ or Co2+. The beta-site is exclusively a transition-metal-ion-binding site thought to be involved in protein conformation, although a metal bound at this site only appears to be essential for activity if Mg2+ is to be bound at the alpha-site. The alpha- and beta-sites may be distinguished from one another by their different abilities to bind divalent-metal ions at different pH values. The occupancy of the beta-site with Zn2+ results in a decrease of protein fluorescence at pH 6. Occupancy of the alpha- and beta-sites with Co2+ results in u.v.-visible spectral changes. Spectroscopic studies with Co2+ have tentatively identified three cysteine residues at the beta-site and one at the alpha-site. Reaction with N-ethyl[14C]maleimide preferentially labels cysteine-130 at the alpha-site when Co2+ occupies the beta-site.

scholarly journals Rational design of metal-binding sites in domain-swapped myoglobin dimers

2021 ◽  
Vol 217 ◽  
pp. 111374
Author(s):  
Satoshi Nagao ◽  
Ayaka Idomoto ◽  
Naoki Shibata ◽  
Yoshiki Higuchi ◽  
Shun Hirota
Keyword(s):  
Metal Binding ◽  
Binding Sites ◽  
Rational Design ◽  
Metal Binding Sites

scholarly journals Electron transfer pathways in photoexcited lanthanide(III) complexes of picolinate ligands

2021 ◽  
Author(s):  
Daniel Kovacs ◽  
Daniel Kocsi ◽  
Jordann A. L. Wells ◽  
Salauat R. Kiraev ◽  
Eszter Borbas
Keyword(s):  
Electron Transfer ◽  
Metal Binding ◽  
Binding Sites ◽  
Secondary Amide ◽  
Metal Binding Sites ◽  
Electron Transfer Pathways

A series of luminescent lanthanide(III) complexes consisting of 1,4,7-triazacyclononane frameworks and three secondary amide-linked carbostyril antennae were synthesised. The metal binding sites were augmented with two pyridylcarboxylate donors yielding octadentate...

scholarly journals Machine learning differentiates enzymatic and non-enzymatic metals in proteins

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ryan Feehan ◽  
Meghan W. Franklin ◽  
Joanna S. G. Slusky
Keyword(s):  
Machine Learning ◽  
Metal Binding ◽  
Binding Sites ◽  
Active Sites ◽  
De Novo ◽  
Enzyme Design ◽  
Metal Binding Sites ◽  
Ensemble Machine Learning ◽  
Machine Learning Model ◽  
Physicochemical Features

AbstractMetalloenzymes are 40% of all enzymes and can perform all seven classes of enzyme reactions. Because of the physicochemical similarities between the active sites of metalloenzymes and inactive metal binding sites, it is challenging to differentiate between them. Yet distinguishing these two classes is critical for the identification of both native and designed enzymes. Because of similarities between catalytic and non-catalytic  metal binding sites, finding physicochemical features that distinguish these two types of metal sites can indicate aspects that are critical to enzyme function. In this work, we develop the largest structural dataset of enzymatic and non-enzymatic metalloprotein sites to date. We then use a decision-tree ensemble machine learning model to classify metals bound to proteins as enzymatic or non-enzymatic with 92.2% precision and 90.1% recall. Our model scores electrostatic and pocket lining features as more important than pocket volume, despite the fact that volume is the most quantitatively different feature between enzyme and non-enzymatic sites. Finally, we find our model has overall better performance in a side-to-side comparison against other methods that differentiate enzymatic from non-enzymatic sequences. We anticipate that our model’s ability to correctly identify which metal sites are responsible for enzymatic activity could enable identification of new enzymatic mechanisms and de novo enzyme design.

The metal-binding sites of glycose phosphates

2009 ◽  
pp. 7934 ◽  
Author(s):  
Kathrin Gilg ◽  
Tobias Mayer ◽  
Natascha Ghaschghaie ◽  
Peter Klüfers
Keyword(s):  
Metal Binding ◽  
Binding Sites ◽  
Metal Binding Sites

scholarly journals Developing Remote Metal Binding Sites in Heteropolymolybdates

2003 ◽  
Vol 2003 (13) ◽  
pp. 2406-2412 ◽  
Author(s):  
Pierre R. Marcoux ◽  
Bernold Hasenknopf ◽  
Jacqueline Vaissermann ◽  
Pierre Gouzerh
Keyword(s):  
Metal Binding ◽  
Binding Sites ◽  
Metal Binding Sites
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