PubMed Health⌕ Search

Biomedical subjects

H Rüterjans

Publications and source records attributed to H Rüterjans.

6 recordsLinked to original sources
PubMed1979

Carbon-13 NMR investigations on ribonuclease A.

The proposed interaction between the amino acid residues Asp 14 and His 48 of ribonuclease A has been confirmed by 13C-NMR spectroscopy. The titration behaviour of the resonance of the side-chain carboxyl group of Asp 14 suggests a pKa of 6.5--7.0 for His 48. An equilibrium between different conformation process of His 48. Upon this deprotonation a hydrogen bond between the side-chains of Asp 14 or His 48 and Tyr 25 seems to be formed as is suggested by the behaviour of a tyrosine C zeta resonance assigned to Tyr 25. One phenylalanine resonance broadens and moves upfield on the addition of the inhibitor Cyd-2'-P, being therefore assigned to Phe 120. The behaviour of this resonance suggests that the upfield shift results from the anisotropy of the cytidine ring. Three signals are assigned to the three Phe residues.

Animals↗
PubMed1978

13C NMR investigations on Npi-[13C1]carboxymethyl-histidine-119 ribonuclease.

The ribonuclease A derivative Npi-[13C1]carboxymethyl-histine-119 ribonuclease prepared by using [13C1]bromoacetate as alkylating reagent has been investigated with high resolution 13C NMR spectroscopy. In the 13C NMR spectra two carbon resonances of relatively high intensity appear which can be assigned to carboxyl groups attached to His-119 and Met-30, their intensity ratio being 10 : 1. The pH dependence of the carbon resonance of the carboxy-methyl group bound to the Npi of His-119 differs in the absence and presence of Cyd-2'-P, thus indicating that the catalytically inactive derivative does bind nucleotides. A mechanism of the alkylation reaction at pH 5.6 is proposed in which the epsilon-amino group of Lys-41 acts as the binding site for the carboxyl group of bromoacetate pushing the bromomethylene group towards the Npi of His-119 or the Ntau of His-12.

Histidine↗
PubMed1977

The phosphoenolpyruvate-dependent phosphotransferase system of Staphylococcus aureus. 3. 1H and 31P nuclear-magnetic-resonance studies on the phosphocarrier protein HPr; tyrosine titration and denaturation studies.

The phosphocarrier protein HPr has been investigated by proton nuclear magnetic resonance (NMR) at 270 MHz in order to evaluate structural properties of the whole molecule and its active site. The titration behaviour of the three tyrosines of the HPr protein was analysed by monitoring the chemical shifts of the aromatic proton resonances of these residues as a function of pH. It was found that the HPr protein contains a lot of slowly exchanging NH backbone protons which suggested a relatively rigid secondary structure of the protein molecule itself although it contains no disulfide bridges. The HPr protein shows a sharp reversible denaturation behaviour at alkaline pH values. Between pH 10.8 and 11.1 two C-2 proton resonance peaks for the single histidine residue could be observed together with abrupt changes in the aromatic and aliphatic absorption region of the HPr protein which are due to chemical exchange processes. The NMR spectrum of the HPr protein is only changed a little upon raising the temperature from 14 degrees C to 70 degrees C. At 76 degrees C all resonances in the spectrum broaden and almost disappear. This process is irreversible.

Bacterial Proteins↗
PubMed1976

15N nuclear magnetic resonance investigations on amino acids.

15N nuclear magnetic resonance investigations of some amino acids were carried out in order to check the applicability of this method to biological problems. Because the natural abundance of the 15N isotope is not sufficient to get readable spectra in a reasonable time, 95% 15N isotope-enriched samples were used for the measurements. Besides the chemical shift values, the line widths, and the nuclear Overhauser enhancement factors, spin lattice relaxation times of the correspondent 15N resonances were measured as functions of pH had temperature.

Amino Acids↗