scholarly journals Solvent dynamics play a decisive role in the complex formation of biologically relevant redox proteins

2020 ◽  
Vol 22 (14) ◽  
pp. 7451-7459 ◽  
Author(s):  
Ellen M. Adams ◽  
Oliver Lampret ◽  
Benedikt König ◽  
Thomas Happe ◽  
Martina Havenith
Keyword(s):  
Complex Formation ◽  
Absorption Spectroscopy ◽  
Critical Factor ◽  
Decisive Role ◽  
Redox Proteins ◽  
Biologically Relevant ◽  
Transient Complex ◽  
Solvent Dynamics ◽  
Thz Absorption

THz absorption spectroscopy reveals that water is a critical factor that governs the transient complex formation of redox proteins. Binding of the substrate creates an entropically favorable complex with bulk-like solvent dynamics.

scholarly journals The staphylococcal biofilm protein Aap forms a tetrameric species as a necessary intermediate before amyloidogenesis

2020 ◽  
Vol 295 (37) ◽  
pp. 12840-12850
Author(s):  
Alexander E. Yarawsky ◽  
Andrew B. Herr
Keyword(s):  
Staphylococcus Epidermidis ◽  
Analytical Ultracentrifugation ◽  
Conformational Transition ◽  
Mechanistic Model ◽  
Critical Factor ◽  
Equilibrium Studies ◽  
Dimer Interface ◽  
Biologically Relevant ◽  
Accumulation Associated Protein ◽  
Initial Assembly

The accumulation-associated protein (Aap) from Staphylococcus epidermidis is a biofilm-related protein that was found to be a critical factor for infection using a rat catheter model. The B-repeat superdomain of Aap, composed of 5–17 B-repeats, each containing a Zn2+-binding G5 and a spacer subdomain, is responsible for Zn2+-dependent assembly leading to accumulation of bacteria during biofilm formation. We previously demonstrated that a minimal B-repeat construct (Brpt1.5) forms an antiparallel dimer in the presence of 2–3 Zn2+ ions. More recently, we have reported the presence of functional amyloid-like fibrils composed of Aap within S. epidermidis biofilms and demonstrated that a biologically relevant construct containing five and a half B-repeats (Brpt5.5) forms amyloid-like fibrils similar to those observed in the biofilm. In this study, we analyze the initial assembly events of the Brpt5.5 construct. Analytical ultracentrifugation was utilized to determine hydrodynamic parameters of reversibly associating species and to perform linked equilibrium studies. Linkage studies indicated a mechanism of Zn2+-induced dimerization similar to smaller constructs; however, Brpt5.5 dimers could then undergo further Zn2+-induced assembly into a previously uncharacterized tetramer. This led us to search for potential Zn2+-binding sites outside of the dimer interface. We developed a Brpt5.5 mutant that was unable to form the tetramer and was concordantly incapable of amyloidogenesis. CD and dynamic light scattering indicate that a conformational transition in the tetramer species is a critical step preceding amyloidogenesis. This mechanistic model for B-repeat assembly and amyloidogenesis provides new avenues for potential therapeutic targeting of staphylococcal biofilms.

Electronic relaxation pathways of the biologically relevant pterin chromophore

2017 ◽  
Vol 19 (20) ◽  
pp. 12720-12729 ◽  
Author(s):  
R. M. DiScipio ◽  
R. Y. Santiago ◽  
D. Taylor ◽  
C. E. Crespo-Hernández
Keyword(s):  
Absorption Spectroscopy ◽  
Transient Absorption ◽  
Relaxation Mechanism ◽  
Transient Absorption Spectroscopy ◽  
Electronic Relaxation ◽  
Biologically Relevant ◽  
Ultrafast Relaxation ◽  
First Time

Femtosecond-to-microsecond transient absorption spectroscopy is used to report the ultrafast relaxation mechanism of 2-amino-1H-pteridin-4-one (pterin) for the first time.

Exploring hydrophobicity by THz absorption spectroscopy of solvated amino acids

2011 ◽  
Vol 150 ◽  
pp. 193 ◽  
Author(s):  
Gudrun Niehues ◽  
Matthias Heyden ◽  
Diedrich A. Schmidt ◽  
Martina Havenith
Keyword(s):  
Amino Acids ◽  
Absorption Spectroscopy ◽  
Thz Absorption

Urea, a Structure Breaker? Answers from THz Absorption Spectroscopy

2012 ◽  
Vol 116 (45) ◽  
pp. 13374-13380 ◽  
Author(s):  
Stefan Funkner ◽  
Martina Havenith ◽  
Gerhard Schwaab
Keyword(s):  
Absorption Spectroscopy ◽  
Thz Absorption
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