Electronic Circular Dichroism of Proteins

Electronic circular dichroism for the detection of microalbuminuria

“…32 The observed spectra (Figure 1) most likely demonstrate HSA (cf Figure 2), given the fact that HSA is the most abundant α-helix-rich plasmatic protein and the first to pass the renal barrier during MAU. 21,32 Because of increased absorption in the deeper ultraviolet region leading to detector saturation, the positive band at~192 nm resulting from π-π* transitions 32 was not reliably detectable. However, the occurrence of both negative bands was sufficient to confirm the presence of HSA in the urine.…”

“…In 1 diabetic patient with clinically confirmed MAU, we detected an ECD spectral pattern (Figure 1) strongly resembling that of α-helix-rich proteins, ie, 2 partially overlapping negative bands at~209 and 222 nm arising from the π-π* and n-π* electronic transitions of the peptide bond, respectively. 32 The observed spectra (Figure 1) most likely demonstrate HSA (cf Figure 2), given the fact that HSA is the most abundant α-helix-rich plasmatic protein and the first to pass the renal barrier during MAU. 21,32 Because of increased absorption in the deeper ultraviolet region leading to detector saturation, the positive band at~192 nm resulting from π-π* transitions 32 was not reliably detectable.…”

“…Despite such indisputable advantages, neither chromatography nor mass spectrometry are used in routine clinical tests for proteinuria/MAU. From another point of view, HSA has a chiral structure (~60% α-helix) 21,32 and, thus, specific spectral pattern being ideally suited for the investigation by chiroptical spectroscopy. In addition, the chiroptical detection of α-helix is highly specific and, thus, false positive results that limit the current clinical procedures are virtually excluded.…”

Handedness preference and switching of peptide helices. Part II: Helices based on noncodedα‐amino acids

“…Most of these chiral carbons bear an aromatic (usually a phenyl, phenol, or a nitrophenyl) moiety directly linked to them. This is a spectroscopically unfortunate situation because the contributions of the electronic transitions of the backbone tertiary amides in the far ultraviolet (UV) region (providing information on the peptoid secondary structures) are severely overlapped by the l α transitions originated from the α ‐aromatic chromophores . The bands in the CD spectrum of the α ‐chiral aliphatic homo‐pentapeptoid H‐( N sch) 5 ‐NH 2 [ N sch, N ‐( S )‐(1‐cyclohexylethyl)glycine] are relatively weak, reflecting only a partial helical ordering in solution .…”

Protein-Ligand Interactions and Allosteric Regulation of Activity in DREAM Protein

“…In the absence of calcium, DREAM showed a broad negative band with fine structured positive and negative peaks. The peaks between 256 nm and 272 nm are likely due to phenylalanine residues whereas the peak between 275 nm and 305 nm are associated with tyrosine and tryptophan residues (Strickland 1974, Woody 2012. Calcium binding resulted in an increase in ellipticity signal between 256 nm and 295 nm ( Figure 5.7b), without a significant shift of the observed vibronic structures.…”