Reductive amination products containing naphthalene and indole moieties bind to melanocortin receptors

Presumed pharmacophoric groups of melanocortin peptides (naphthalene, amino or guanidine, and indole moieties) were combined in mimetics molecules looking for their favorable location for activity at melanocortin (MC) receptors. Twenty-two compounds were prepared and tested. The best of these displayed micromolar affinities for the MC receptors.     

Structural studies of the lipopolysaccharide of Moritella viscosa strain M2-226

The structure of the O-specific side chain of the lipopolysaccharide from the Gram-negative psychrophilic bacterium Moritella viscosa strain M2-226, responsible for the winter ulcer in Atlantic salmon, has been determined. Monosaccharide analysis and (1)H and (13)C NMR spectroscopy were employed to elucidate the structure. It was concluded that the polysaccharide is composed of a trisaccharide repeating unit with the following structure: →3)-β-D-GlcpNAc-(1→4)-[α-D-GlcpA-(1→3)]-α-L-Fucp-(1→ .     

Chlorpromazine interaction with phosphatidylserines: a (13)C and (31)P solid-state NMR study

Niemann-Pick type C, or NPC for short, is an early childhood disease exhibiting progressive neurological degeneration, associated with hepatosplenomegaly in some cases. The disease, at the cellular level, is a result of improper trafficking of lipids such as cholesterol and glycosphingolipids (GSLs) to lysosome-like storage organelles (LSOs), which become engorged with these lipids. It is believed that the initial defect in trafficking, whether of cholesterol or a GSL, results in an eventual traffic jam in these LSOs. This leads to the retention of not only other lipids, but also of transmembrane proteins that transiently associate with the late endosomes (LE) in normal cells, on their way to other cellular destinations such as the trans-Golgi network (TGN). In this review, we discuss the biophysical properties of lipids and cholesterol that might determine their intracellular itineraries, and how these itineraries are altered in NPC cells, which have defects in the proteins NPC1 or NPC2. We also discuss some potential therapeutic directions being suggested by recent research.     

N-alkylaminoacids and their derivatives interact with melanocortin receptors

Thirty four N-alkylaminoacids (Arg, Trp, Nal, Pro, Hyp, L and D) and derivatives were prepared by a process that included reductive alkylation of the amino function. Both solid phase and solution synthesis was used. Title substances displayed binding activity on melanocortin receptors MC(1,3-5) reaching the low micromolar range.     

Classification of G-protein coupled receptors by alignment-independent extraction of principal chemical properties of primary amino acid sequences

We have developed an alignment-independent method for classification of G-protein coupled receptors (GPCRs) according to the principal chemical properties of their amino acid sequences. The method relies on a multivariate approach where the primary amino acid sequences are translated into vectors based on the principal physicochemical properties of the amino acids and transformation of the data into a uniform matrix by applying a modified autocross-covariance transform. The application of principal component analysis to a data set of 929 class A GPCRs showed a clear separation of the major classes of GPCRs. The application of partial least squares projection to latent structures created a highly valid model (cross-validated correlation coefficient, Q(2) = 0.895) that gave unambiguous classification of the GPCRs in the training set according to their ligand binding class. The model was further validated by external prediction of 535 novel GPCRs not included in the training set. Of the latter, only 14 sequences, confined in rapidly expanding GPCR classes, were mispredicted. Moreover, 90 orphan GPCRs out of 165 were tentatively identified to GPCR ligand binding class. The alignment-independent method could be used to assess the importance of the principal chemical properties of every single amino acid in the protein sequences for their contributions in explaining GPCR family membership. It was then revealed that all amino acids in the unaligned sequences contributed to the classifications, albeit to varying extent; the most important amino acids being those that could also be determined to be conserved by using traditional alignment-based methods.     

Binding of type-I and type-II collagens to Staphylococcus aureus strains isolated from patients with toxic shock syndrome compared to other staphylococcal infections

Abstract Toxic shock syndrome toxin-1 (TSST-1) producing strains of Staphylococcus aureus isolated from 18 patients with toxic shock syndrome (TSS) and from 56 patients with other diagnoses were compared for capacity to interact with various serum and connective tissue proteins. TSS associated isolates showed significantly stronger binding of Type-I collagen (Cn-I) and Cn-II than non-TSS strains, in a particle agglutination assay (PAA) as well as in ¹²⁵I labelled Cn uptake experiments. ¹²⁵I Cn-IV binding, was similar between the two groups, whereas in PAA, a stronger interaction was observed for non-TSS than TSS associated strains. The median binding of ¹²⁵I Cn to TSS-associated strains were 52.2 (Cn-I), 30.6 (Cn-II) and 20.0 (Cn-IV) compared to 20.0 (Cn-I), 14.4 (Cn-II) and 24.4 (Cn-IV) values of non-TSS strains. A saturation with ¹²⁵I Cn-I and Cn-II binding was established for TSS (30 min) and non-TSS (15 min) strains. ¹²⁵I Cn-IV binding reached a saturation in 10 min and 90 min with TSS and non-TSS strains respectively. Finally, the binding profiles of TSS associated and non-TSS strains to fibronectin, fibrinogen, laminin and IgG did not differ in both PAA and radioisotope assays. In scanning electron microscopy, cells of TSS associated strains bound to the reprecipitated native Cn-I fibrils. In contrast, most cells of non-TSS strains were localized to the distal end or were trapped between the Cn fibrils. The stronger interaction with Cn-I and II in particular, shown by TSS associated strains, might enhance submucosal localization, thereby facilitating entry of toxins into the blood and establishment of TSS.     

Correction of chlorophyll-defective male-sterile winter oilseed rape (Brassica napus) through organelle exchange: molecular analysis of the cytoplasm of parental lines and corrected progeny

Summary Cytoplasmic differences between male-fertile and male-sterile Brassica napus as well as Raphanus sativus were investigated. Plastids of the male-fertile B. napus were found to differ from those of male-sterile B. napus and R. sativus with respect to DNA restriction enzyme patterns. Differences between male-fertile and male-sterile B. napus mitochondria were detected not only in the restriction fragment patterns of their DNA, but also at the level of expression by in organello translation of mitochondrial polypeptides.The chlorophyll deficiency obtained upon transferral of the male-sterility-conferring radish cytoplasm to a winter variety of B. napus had been corrected earlier through protoplast fusion. The cytoplasmic composition of the corrected lines was analysed using DNA restriction analysis and in organello translation. The stability of the recombined cytoplasm in the corrected lines was confirmed by analysis of the subsequent seed-derived generation.