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N Helbecque

Publications and source records attributed to N Helbecque.

63 records · Page 4Linked to original sources
PubMed1984

Conformation of physalaemin.

The conformational and spatial configuration of the biologically active undecapeptide physalaemin was studied using 350-MHz1H NMR. The NMR analyses suggested the existence of a strong hydrogen bond between the amide proton of the Phe7 and a carbonyl group in the N-terminal moiety, most likely the Pro4 one. Other bondings were postulated, involving the side-chain amine of Lys6 and the side-chain amide of Asn5 and respectively the side-chain carboxyl of Asp3 and the terminal amide carbonyl of Met-NH2. Thus unlike its shorter peptidic fragments, physalaemin exhibited a stable molecular structure in solution, giving some insight into the conformation required for interaction at the biological receptor of tachykinins.

Hydrogen Bonding↗
PubMedDate not supplied

Effect of the angiotensin I-converting enzyme I/D polymorphism on cognitive decline. The EVA Study Group.

Several clinical, epidemiological, and pathological observations suggest that vascular risk factors are associated with cognitive performances. The renin-angiotensin system components, major determinants of the cardiovascular system, are expressed in the brain. To estimate their potential impact on cognitive performances, we studied the association between cognitive functioning and an insertion/deletion (I/D) polymorphism of the angiotensin I-converting enzyme (ACE) gene. In a sample of 1168 highly performing subjects (59-71 years), DD homozygotes had the lowest cognitive scores as evaluated by the Mini-Mental State Examination. Cognitive decline at 4-year follow-up (defined as the loss of at least 3 points in Mini-Mental State Examination score) was more prevalent in these subjects, the odds ratio being equal to 1.53 (95% CI: 1.04-2.24) with subjects ID as reference class. Moreover, the combined effect of the presence of at least one APOE epsilon4 allele and ACE DD homozygosity was a risk factor for cognitive decline. This report reinforces the hypothesis of an influence of cardiovascular risk factors on cognitive performances.

Age Distribution↗
PubMedDate not supplied

Interaction with DNA of oligopeptides related to the Arc repressor.

Three different peptides, A13, A14x2 and A20, related to the Arc repressor from Salmonella phage P22, were synthesized. They all contained the 13 N-terminal residues of Arc known to form a beta-sheet interacting with the operator OArc. In the case of A20, the tripeptide Lys-Trp-Lys was added in the C-terminal position because of its propensity to increase affinity to DNA. The interaction of the three peptides with OArc and with other related (OMnt from the same phage) and unrelated oligonucleotides was followed using circular dichroism, filter binding assays and DNaseI protection experiments. While Kd = 10(-9) M for the protein, 8.7 x 10(-5) M and 7.7 x 10(-6) M Kd values were obtained for A14x2 and A20 interacting with OArc.

Amino Acid Sequence↗