Heng Chi

• PhD
• Laboratory Manager at Jiangsu food and pharmaceutical science college, China, Jiangsu

Site‐selected dynamics of a three‐stranded β‐sheet peptide were probed by laser‐excited temperature‐jump infrared spectroscopy and isotopic labeling. Relaxation time constants showed an enhanced sensitivity to vibrational coupling. For more details, see the Full Paper by T. A. Keiderling, K. Hauser and co‐workers on page 3524 ff.

Site‐specific isotopic labeling of molecules is a widely used approach in IR spectroscopy to resolve local contributions to vibrational modes. The induced frequency shift of the corresponding IR band depends on the substituted masses, as well as on hydrogen bonding and vibrational coupling. The impact of these different factors was analyzed with a...

Infrared detected temperature jump (T-jump) spectroscopy and site-specific isotopic labeling were applied to study a model three-stranded β-sheet peptide with the goal of individually probing the dynamics of strand and turn structural elements. This peptide had two DPro-Gly (pG) turn sequences to stabilize the two component hairpins, which were lab...

A series of closely related peptide sequences that form triple-strand structures were designed with a variation of cross-strand aromatic interactions and spectroscopically studied as models for β-sheet formation and stabilities. Structures of the three-strand models were determined with NMR methods and temperature-dependent equilibrium studies carr...

DPro followed by a flexible residue, such as Gly. A 19-residue peptide (B3) was synthesized with alternating hydrophobic and hydrophilic residues connected by symmetrical DPro-Gly and Gly-DPro turns. B3 forms an oligomeric aggregate, rich in ß-sheet conformation, which reversibly transforms into unordered structure on heating as evidenced by its te...

Beta-sheet conformation is promoted in peptides with amphiphilic design, and type II’ beta turn is favored with the unnatural amino acid D-Pro followed by a flexible residue, such as Gly. A 19mer peptide (B3pG) was synthesized with alternating hydrophobic and hydrophilic residues connected by symmetrical D-Pro-Gly and Gly-D-Pro turns. B3pG forms an...

Turn residues as well as side-chain interactions play an important role for the folding of ß-sheets. We investigated the conformational dynamics of a three-stranded ß-sheet peptide (DPDP) and a two-stranded ß-hairpin (WVYY-DP) by time-resolved temperature-jump infrared spectroscopy. Both peptide sequences contain DPro-Gly residues that favor a tigh...

Formation of peptide aggregates and fibrils must ultimately be driven by interactions of side chains. Typically the lower solubility of hydrophobic sequences favors desolvation by formation of interchain contacts which are then stabilized further by various means. One way is development of ordered interdigitization of the side chains, which is part...

Polyglutamic acid at low pH forms aggregates and self-assembles into a spiral, fibril-like superstructure formed from a β2 type sheet conformation that has a more compact intersheet packing than commonly found. This is stabilized by three-centered bifurcated hydrogen bonding of the amide carbonyl involving the protonated glutamic acid side chain. W...

Aggregation and fibrilization have been determined to be ubiquitous properties of protein and peptide systems placed under various forms of stress. Most such systems have secondary structures with high beta sheet content, but this can vary greatly in detail. While the most fundamental variance is the difference in parallel and anti-parallel interst...

Selected examples of turn sequence and hydrophobic contact stabilized β-hairpin peptides were previously studied using ECD, fluorescence, IR and VCD spectroscopies to assess stability of β-hairpin formation. Extending this, two three-stranded β-sheet peptides, based on modified Trpzip sequences, using D-Pro-Gly (B3pG) or Asn-Gly (B3GN) turn sequenc...

Unordered proteins, unfolded peptides, and several "random coil" models have been shown to have local conformations similar to that of polyproline II (PPII). Inter-residue coupling of selected residues in a series of related peptides having predominantly PPII conformations were measured using IR, VCD, and Raman spectra of selected variants that wer...

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