Near UV-Visible electronic absorption originating from charged amino acids in a monomeric protein

Prasad, Saumya; Mandal, Imon; Singh, Shubham; Paul, Ashim; Mandal, Bhubaneswar; Venkatramani, Ravindra; Swaminathan, Rajaram

doi:10.1039/c7sc00880e

Cited by 161 publications

(176 citation statements)

References 49 publications

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“…Titration of Cu II into C‐peptide similarly resulted in an increased absorbance in the region at λ =280–300 nm, corresponding to a deprotonated backbone amide to Cu II charge transfer or interactions between charged side chains . Increased absorption at λ =600 nm was observed upon the addition of Cu II , which was consistent with a d–d transition at the Cu II center (Figure B).…”

Section: Figurementioning

confidence: 75%

“…Titration of Cr III show changes in the spectral profile relative to that of apo C‐peptide with increases in absorption at λ =260–300 nm (Figure A). Bands in this region may correspond to a weak d–d transition ( 4 A 2g → 4 T 1 (t 2 e 2 )); a strong carboxylate oxygen–metal charge transfer; interactions between charged groups, such as a glutamate side chain and the amino terminus; or a combination of the three; thus, the resulting spectral shifts may be attributed to either the introduction of a Cr III /C‐peptide complex or an electrostatic rearrangement between two charged amino acids in the sequence.…”

Section: Figurementioning

confidence: 99%

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Analysis of Metal Effects on C‐Peptide Structure and Internalization

et al. 2019

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The connecting peptide (C‐peptide) has received increased attention for its potential therapeutic effects in ameliorating illnesses such as kidney disease and diabetes. Although the mechanism of C‐peptide signaling remains elusive, evidence supports its internalization and intracellular function. Emerging research is uncovering the diverse biological roles metals play in controlling and affecting the function of bioactive peptides. The work presented herein investigates interactions between C‐peptide and first‐row d‐block transition metals, as well as their effects on C‐peptide internalization into cells. Through spectroscopic techniques, it is demonstrated that CrIII, CuII, and ZnII bind to C‐peptide with differing stoichiometries and biologically relevant affinities. In addition, metal binding elicits both subtle changes in secondary structure and inhibits adoption of an α‐helical character in environments where the dielectric constants are reduced. This study shows how metal ions can modulate peptide hormone activity through subtle structural changes to disrupt cellular uptake.

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Section: Figurementioning

confidence: 75%

Section: Figurementioning

confidence: 99%

Analysis of Metal Effects on C‐Peptide Structure and Internalization

et al. 2019

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“…The nature of the optical properties is sensitive to the environment in which the glutamine molecules reside. It has previously been reported that charged amino acids already display an absorption in the range of 250-350 nm that is significantly red shifted (36, 37). The origins of the low energy absorption were attributed to charge transfer excitations.…”

Section: Resultsmentioning

confidence: 99%

Short hydrogen bonds enhance non-aromatic protein-related fluorescence

Stephens

Qaisrani

Ruggiero

et al. 2020

Preprint

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Disentangling the origin of the optical activity of non-aromatic proteins is challenging due to their size and thus their high computational requisites. Here we show, in a much smaller model system, that the single amino acid glutamine undergoes a chemical transformation leading to an unreported glutamine-like structure which has a similar broad absorption spectrum reported previously for non-aromatic proteins. We further show computationally that the optical activity of the glutamine-like structure is directly coupled to short-hydrogen bonds, but also displays charge and vibrational fluctuations, the latter of which are also present in less optically active structures such as in L-glutamine. Since experimentally the glutamine-like structure is the brightest structure, we conclude that short-hydrogen bonds are the ones responsible for the large Stokes shift observed in optically active non-aromatic proteins.

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“…Those amino acids having a strong (s; probability for non-specificity, Corr P < 10 −4 ) or moderate (m; Corr P < 10 −3 ) or weak (w; Corr P < 10 −2 ) association of their binding sites with their cognate codons/anticodons (Corr P = 1 implies no specificity; see table 1 of [44]) are also those that have the greatest number of characteristics relevant to increased photon dissipation, and therefore reproduction through the dissipation-replication relation, at the origin of life. The " * " indicates amino acids that absorb in the 260 nm window through charge transfer (CT) transitions [64]. and hydrophobic parts, that can adsorb to DNA or RNA and thereby keep them afloat at the surface would have been essential to photon dissipation.…”

Section: Accumulation Of Information Through the Dissipation-replicatmentioning

confidence: 99%

“…This is an 5-member aromatic heterocycle containing two nitrogen atoms and 3 carbon atoms known as an imidazole. Having two conjugate bonds, histidine absorbs strongly in the UVC (212 nm, = 5, 700) [76], however, it has a smaller absorption peak at 280 nm which has been attributed to photon-induced charge transfer (CT) transitions [64]. This could be important to the origin of life because imidazoles are known as amphoteric molecules, serving as both an acidic and alkaline (pKa = 14.5) catalyst for a very large number of important reactions in contemporary life, for example as a condensing agents for the phosphorylation of the nucleobases and the lipids.…”

Section: Catalysismentioning

confidence: 99%

Entropy Production as the Origin of Information Encoding in RNA and DNA

Mejía¹,

Michaelian²

2019

Preprint

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Ultraviolet light incident on organic material can initiate its spontaneous dissipative structuring into chromophores which can catalyze their own replication. This may have been the case for one of the most ancient of all chromophores dissipating the Archean UVC photon flux, the nucleic acids. Oligos of nucleic acids with affinity to particular amino acids which foment UVC photon dissipation would have been selected through non-equilibrium thermodynamic imperatives which favor entropy production. Indeed, we show here that those amino acids with characteristics most relevant to fomenting UVC photon dissipation are precisely those with greatest chemical affinity to their codons or anticodons. Entropy production could thus provide an explanation for the accumulation of information in nucleic acids relevant to the dissipation of the externally imposed thermodynamic potentials. The accumulation of information in this manner provides a link between evolution and entropy production.

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Near UV-Visible electronic absorption originating from charged amino acids in a monomeric protein

Abstract: We report 250–800 nm UV-Vis monomeric protein absorption originating from protein backbone–sidechain and sidechain–sidechain charge transfer transitions involving Lys/Glu residues.

Cited by 161 publications

References 49 publications

Analysis of Metal Effects on C‐Peptide Structure and Internalization

Analysis of Metal Effects on C‐Peptide Structure and Internalization

Short hydrogen bonds enhance non-aromatic protein-related fluorescence

Entropy Production as the Origin of Information Encoding in RNA and DNA

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