Synthesis, purification and initial structural characterization of octarellin, a de novo polypeptide modelled on the alpha/beta-barrel proteins

in Protein Engineering (1990), 3(4), 259-66

We have attempted to construct an artificial polypeptide that folds like the eight-stranded parallel beta-barrel structures. Our approach consists of repeating eight times a unit peptide designed to adopt ... [more ▼]

We have attempted to construct an artificial polypeptide that folds like the eight-stranded parallel beta-barrel structures. Our approach consists of repeating eight times a unit peptide designed to adopt a 'beta-strand/alpha-helix' pattern. A first 'test' sequence for this structural unit was deduced from a series of parameters defined after an analysis of three natural alpha/beta-barrel proteins and including principally the lengths of the secondary structure elements, the alpha/beta packing and the fitting on average Garnier profiles. The gene encoding this structural unit was synthesized, cloned and expressed in Escherichia coli either as a monomer or as direct repeats of 2-12 units. Preliminary structural characterization of the 7-, 8- and 9-fold unit polypeptides by circular dichroism measurements indicates the presence of the predicted amount of alpha-helix in the three proteins. Further analysis by urea-gradient gel electrophoresis demonstrates that, in the conditions tested, only the 8-fold unit polypeptide forms a compact structure through a cooperative and rapid two-state folding transition involving long-range molecular interactions. [less ▲]

Synthesis, quality control and in vivo evaluation of [I-123] rhTIMP-2, a potential tumour-imaging agent

in Journal of Labelled Compounds & Radiopharmaceuticals (2005), 48(5), 387-396

Matrix metalloproteinases (MMPs) are enzymes involved in the turnover of the extracellular matrix. Their overexpression in tumours may provide a target for diagnostic imaging by using labelled MMP ... [more ▼]

Matrix metalloproteinases (MMPs) are enzymes involved in the turnover of the extracellular matrix. Their overexpression in tumours may provide a target for diagnostic imaging by using labelled MMP inhibitors. MMPs are inhibited by endogenous tissue inhibitors of metalloproteinases (TIMPs). The enhanced production of MT1-MMP, located on the surface of cells within or in the direct vicinity of the tumour, and the high affinity interaction between TIMP-2 and MT1-MMP suggested that TIMP-2 could be a potential agent for non-invasive monitoring of cancer MMP levels, diagnosis of primary and secondary tumours and tumour response to MMP inhibitor therapy. There is also evidence that I-125-rhTIMP-2 internalizes, which is an important feature for its possible use as a radiotherapeuticum if labelled with I-131. Labelling of rhTIMP-2 was performed using the iodogen method resulting in a radiochemical yield of 51.1 +/- 11.8% (n = 5) and a radiochemical purity of > 98%. The trichloroacetic acid (TCA) precipitability of I-123 rhTIMP-2 was 95.2%. SDS-PAGE confirmed the correct size (21 kDa) of the purified I-123 rhTIMP-2 without degradation. HPLC showed one radioactive peak with a retention time corresponding to the nonlabelled rhTIMP-2. In vivo biodistribution showed no long-term accumulation in organs and the possibility to accumulate in the tumour. These results show the potential of I-123 rhTIMP-2 as tumour-imaging agent. Copyright (c) 2005 John Wiley [less ▲]

Synthesis: tension-type headache mechanisms

in Olesen, J.; Tfelt-Hansen, P.; Welch, K. M. A. (Eds.) The Headaches (1999)

Synthetic and mechanistic inputs of photochemistry into the bisacetylacetonatocobalt- mediated radical polymerization of n-butyl acrylate and vinyl acetate

in Polymer Chemistry (2012), 3(7), 1856-1866

The input of photochemistry to the Co(acac)2 mediated radical polymerization (CMRP) of n-butyl acrylate and vinyl acetate is investigated for the first time. Upon UV irradiation, photoinitiators are able ... [more ▼]

The input of photochemistry to the Co(acac)2 mediated radical polymerization (CMRP) of n-butyl acrylate and vinyl acetate is investigated for the first time. Upon UV irradiation, photoinitiators are able to initiate the n-butyl acrylate polymerization that remains controlled up to very high molar masses (>4 × 106 g mol−1) with low polydispersities. The photoinitiator as well as the irradiation time must be appropriately chosen to reach acceptable initiator efficiencies while maintaining an optimal control over the polymerization. Laser flash photolysis experiments were then carried out to evidence the addition of alkyl and phosphonyl radicals onto Co(acac)2 and to determine the rate constants (kdeact) of these addition reactions that were still lacking. Finally, both kinetics of polymerization and spin-trapping experiments have evidenced that the C–Co bond at the extremity of the dormant polymer chains can be easily photocleaved. UV irradiation can therefore be considered as an additional lever for tuning the reactivity of the CMRP process mediated by Co(acac)2. [less ▲]

Synthetic aperture co-phasing and co-alignment using an external reference source

in Proceedings of ICSO 2006 (2006, June 27)

A breadboard set-up has demonstrated a concept of co-phasing and co-alignment based on an external reference source for synthetic aperture telescopes applications. These types of systems can be extremely ... [more ▼]

A breadboard set-up has demonstrated a concept of co-phasing and co-alignment based on an external reference source for synthetic aperture telescopes applications. These types of systems can be extremely valuable in order to perform coarse re-alignment of synthetic aperture telescope, following thermo-elastic deformation and deployment effects in space flight environments. [less ▲]

Synthetic Biomedical Polymers (Part B)

Poster (1991, May 31)

Synthetic Biomedical Polymers. Part A. a. "Original way to the macromolecular engineering of polyesters : polylactides and poly e-caprolactone". b. "Their formulation and application as embolic material

Poster (1991, January 16)

Synthetic model peptides for apolipoproteins. I. Design and properties of synthetic model peptides for the amphipathic helices of the plasma apolipoproteins.

in Biochimica et Biophysica Acta (1993), 1170(1), 1-7

Amphipathic helical peptides are the lipid-binding motives of the plasma apolipoproteins, and synthetic peptide analogs have been used to unravel the mechanism of lipid association within this class of ... [more ▼]

Amphipathic helical peptides are the lipid-binding motives of the plasma apolipoproteins, and synthetic peptide analogs have been used to unravel the mechanism of lipid association within this class of proteins. Hydrophobic interactions between the apolar amino acid residues belonging to the hydrophobic face of the amphipathic helices and the lipids are the major driving forces in the peptide-lipid association to form discoidal complexes. Ionic interactions and salt bridge formation between contiguous peptide chains in the complex can, however, contribute to the overall stability of the lipid-protein particle. This was studied by designing peptide analogs to the helical repeats of the apolipoproteins with variable degrees of salt bridge formation between adjacent peptide chains. The most stable conformation for pairs of synthetic peptides was calculated by energy minimisation together with the energy of interaction between peptides. The sequence of the peptides was derived from that of the 18A peptide synthesized by Segrest et al., and the theoretical calculations confirmed that ionic interactions between residues close to each other, along the edge of two adjacent anti-parallel peptides, can significantly contribute towards the stability of a peptide-phospholipid complex. [less ▲]

Synthetic peptide inhibitors of transpeptidation by the exocellular DD-carboxypeptidase-transpeptidase from Actinomadura R39

in FEBS Letters (1981), 123(1), 75-78

Synthetic pulsational line profile variations

in Astrophysics & Space Science (2010), 329

We have produced simulated time series of high resolution spectroscopy for sdBs. We present the first results of testing classical mode identification techniques. Here, in particular, we analyse the ... [more ▼]

We have produced simulated time series of high resolution spectroscopy for sdBs. We present the first results of testing classical mode identification techniques. Here, in particular, we analyse the behaviour of individual spectral lines and discuss the results and applicability of the moment method. [less ▲]