Turn conformations in peptides containing the -Xaa-Ser- sequence.

The conformations of the protected dipeptides Boc-L-Pro-L-Ser-NHMe, Boc-L-Pro-D-Ser-NHMe, Boc-L-Val-L-Ser-NHMe and Boc-L-Val-D-Ser-NHMe have been explored through interpretation of their infrared spectra in CH2Cl2, DMSO and D2O solution. In CH2Cl2 solution the formation of a ten-membered ring (beta-turn) for each compound is signaled by characteristic shifts in both the urethane C = O and the terminal NH stretching frequencies. For each peptide, differences in the amide I absorption patterns for LL and LD isomers are consistent with the formation of type I and type II beta-turns respectively in CH2Cl2 solution.

A search for the ideal type I beta-turn.

In 1968 C. Venkatachalam (Biopolymers, Vol. 6, pp.

Chaperone SecB: conformational changes demonstrated by circular dichroism.

The chaperone SecB, which is involved in protein export in Escherichia coli, is shown by circular dichroism measurements to contain a high content of beta-pleated sheets. Prediction of the secondary structure of SecB is in good agreement with the observed content of beta-sheet. In accordance with the previous studies in which changes in conformation were assessed indirectly [Randall (1992), Science 257, 241-245], here we show that the conformation of SecB changes with the concentration of salt in the milieu and also when SecB interacts with a peptide ligand.

Complexes of aluminium with peptide ligands: a Fourier transform IR spectroscopic study.

Aluminium has been recognized to be a neurotoxic agent and a risk factor in Alzheimer's disease and other neuronal dysfunctions. CD spectroscopic studies on two synthetic fragments of the human neurofilament protein midsized subunit (NF-M), and their alanine-for-serine-substituted and/or serine-phosphorylated derivatives showed the formation of stable, citric acid resistant complexes of Al3+ with peptide ligands [M. Hollósi, Z.

A poly(ethylene glycol) water-soluble conjugate of porin: refolding to the native state.

Porin, from Rhodabacter capsulatus, was chemically modified with methoxypoly(ethylene glycol) (m-PEG; molecular mass = 5000 Da) succinimidyl carbonate to yield methoxypoly(ethylene glycol)-porin (m-PEG-SC-Porin), as previously reported for bacteriorhodopsin [Sirokman, G., & Fasman, G. D.