Conformational Dependence of Electronic Coupling Across Peptide Bonds: A Ramachandran Map

SummaryThe effects of trypsin and plasmin on the functional and physicochemical properties of purified human fibrinogen were observed at various stages of proteolysis. Concentrations of plasmin and trypsin that produced fibrinogenolysis at comparable rates as measured in a pH stat produced, at similar rates, loss of precipitability of fibrinogen by heat and ammonium sulphate and alterations in electrophoretic mobility on starch gel. Trypsin produced a more rapid loss of clottability of fibrinogen and a more rapid appearance of inhibitors of the thrombin-fibrinogen clotting system than did plasmin. Consistent differences were noted between the effects of trypsin and plasmin on the immunoelectrophoretic properties of fibrinogen during the early stages of proteolysis.These results are consistent with the hypothesis that trypsin initially reacts with the same peptide bonds of fibrinogen that are split by thrombin, but these same bonds do not appear to be split initially by plasmin. Measurement of the various functional and physico-chemical changes produced by the action of trypsin and plasmin on fibrinogen can be used to recognize various stages of proteolysis.

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Stereodivergent Alkyne Hydrofluorination Using a Simple Practical Reagent

10.26434/chemrxiv.11962629.v3 ◽

2020 ◽

Author(s):

Rui Guo ◽

Xiaotian Qi ◽

Hengye Xiang ◽

Paul Geaneoates ◽

Ruihan Wang ◽

...

Keyword(s):

Bond Formation ◽

Biologically Active ◽

Dft Studies ◽

Thermodynamic Control ◽

Important Goal ◽

Peptide Bonds ◽

Metal Free ◽

Vinyl Cation ◽

E And Z Isomers ◽

Vinyl Fluorides

Vinyl fluorides play an important role in drug development as they serve as bioisosteres for peptide bonds and are found in a range of biologically active molecules. The discovery of safe, general and practical procedures to prepare vinyl fluorides remains an important goal and challenge for synthetic chemistry. Here we introduce an inexpensive and easily-handled reagent and report simple, scalable, and metal-free protocols for the regioselective and stereodivergent hydrofluorination of alkynes to access both the E and Z isomers of vinyl fluorides. These conditions were suitable for a diverse collection of alkynes, including several highly-functionalized pharmaceutical derivatives. Mechanistic and DFT studies support C–F bond formation through a vinyl cation intermediate, with the (E)- and (Z)-hydrofluorination products forming under kinetic and thermodynamic control, respectively.<br>

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Electronic Coupling and Transport in Non-covalent Inorganic Nanoscale Assemblies

10.29363/nanoge.ngfm.2019.298 ◽

2019 ◽

Author(s):

Dmitri Talapin

Keyword(s):

Electronic Coupling

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On haemoglobin. XIII. Peptide structures around arginine and lysine residues in the molecule of some mammalian haemoglobins and the liberation of the peptide bonds by the actions of trypsin

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19621284 ◽

1962 ◽

Vol 27 (5) ◽

pp. 1284-1291

Author(s):

M. Teleha ◽

P. Mäsiar

Keyword(s):

Peptide Bonds ◽

Lysine Residues

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Thermochromic aggregation-induced dual phosphorescence via temperature-dependent sp3-linked donor-acceptor electronic coupling

Nature Communications ◽

10.1038/s41467-021-21676-5 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Tao Wang ◽

Zhubin Hu ◽

Xiancheng Nie ◽

Linkun Huang ◽

Miao Hui ◽

...

Keyword(s):

Excited State ◽

Room Temperature ◽

Electronic Coupling ◽

Temperature Dependent ◽

Molecular Systems ◽

Donor And Acceptor ◽

Theoretical Investigations ◽

Donor Acceptor ◽

And Control ◽

Two Temperature

AbstractAggregation-induced emission (AIE) has proven to be a viable strategy to achieve highly efficient room temperature phosphorescence (RTP) in bulk by restricting molecular motions. Here, we show that by utilizing triphenylamine (TPA) as an electronic donor that connects to an acceptor via an sp3 linker, six TPA-based AIE-active RTP luminophores were obtained. Distinct dual phosphorescence bands emitting from largely localized donor and acceptor triplet emitting states could be recorded at lowered temperatures; at room temperature, only a merged RTP band is present. Theoretical investigations reveal that the two temperature-dependent phosphorescence bands both originate from local/global minima from the lowest triplet excited state (T1). The reported molecular construct serves as an intermediary case between a fully conjugated donor-acceptor system and a donor/acceptor binary mix, which may provide important clues on the design and control of high-freedom molecular systems with complex excited-state dynamics.

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