Mapping of a discontinuous and highly conformational binding site on follicle stimulating hormone subunit-β (FSH-β) using domain Scan™ and Matrix Scan™ technology

This paper describes the application of two novel screening technologies, i.e. Domain Scan (24- and 30-mer peptides) and Matrix Scan (24-mer peptides) technology, in the mapping of a discontinuous epitope on FSH-beta for a series of 20 monoclonal antibodies. 11 out of 20 mAb's, mapping of which was not successful by conventional Pepscan technology (12-mer peptides), showed selective binding to peptide-constructs corresponding to the beta3-loop of FSH in the Domain and/or Matrix Scan. Systematic replacement analysis studies with peptide-construct 57VYETVRVPGCAC-SAc-ADSLYTYPVATQ81 revealed that for most mAb's the amino acids R62, A70, D71, and L73 form the core of the epitope. A Domain Scan performed in the C-O format showed highly selective binding for mAb's 1 and 2 with only three beta1-beta3 peptide-constructs covering the residues 60TVRVPGCAHHADSLY74 in combination with 10IAIEKEECRFAI21, while for mAb 10 binding was observed with peptide-constructs containing the C-terminal residues 97RGLGPSYCSFGEMKE114 in combination with the residues 10IAIEKEECRFAI21. A Matrix Scan of mAb 17 showed that peptides from four different regions on FSH (1st strand beta3-loop, alpha 1-loop, long alpha2-loop, det. loop) showed enhanced binding in combination with several 70ADSL73-containing peptides. BIACORE measurements with mAb's 1, 2, 13, and 17 using a set of 21 different peptide(-construct)s partially confirmed the Domain and Matrix Scan screening results. Only 24- and 33-mer peptides covering both the 1st and 2nd strand of the beta3-loop showed measurable binding. Cyclic beta3-loop peptide mimics were found to bind significantly stronger (Kd approximately 5 microM) than the lineair analogues, in agreement with the fact that the discontinuous epitope is part of a loop structure. Coupling of the lineair beta1-peptide 1oIAIEKEECRFAI21 to the linear beta3-peptide *52TFKELVYETVRVPGCAHHADSLYTYPVATQAH83# via disulfide bond formation showed a 2-3 fold increase in Kd, thus conforming participation of the beta 1-loop in antibody binding for these mAb's.     

Creating monolayers and thin films of a novel bis(alkyl) substituted asymmetrical polyoxotungstate, [[CH3(CH2)11Si]2OSiW11O39]4- using the Langmuir-Blodgett technique

A bis(alkyl) substituted, asymmetric polyoxometalate [[CH3(CH2)3]4N]4[[CH3(CH2)11Si]2OSiW11O39], was prepared and incorporated into monolayer and multilayer thin films using Langmuir-Blodgett techniques.     

The structured design of cryptographically good s-boxes

We describe a design procedure for the s-boxes of private key cryptosystems constructed as substitution-permutation networks (DES-like cryptosystems). Our procedure is proven to construct s-boxes which are bijective, are highly nonlinear, possess the strict avalanche criterion, and have output bits which act (vitually) independently when any single input bit is complemented. Furthermore, our procedure is very efficient: we have generated approximately 60 such 4 × 4 s-boxes in a few seconds of CPU time on a SUN workstation.This work was partially supported by a grant from the Natural Sciences and Engineering Research Council of Canada.     

Conformational studies of 2-methylbutyronitrile and 3-methyl-1-pentyne by vibrational spectroscopy and molecular mechanics

Vibrational spectra were obtained for the structurally similar compounds 2-methylbutyronitrile and 3-methyl-1-pentyne, and vibrational assignments were made with the aid of normal coordinate calculations. Molecular mechanics calculations were also made, and each compound was shown to exist as a mixture of three conformers, with the most stable conformer being the one with the two methyl groups trans to each other. Results of the calculations are given.     

Anomalous atomic hydrogen shock pattern in a supersonic plasma Jet

A two-photon laser-induced fluorescence study on the transport of ground-state atomic hydrogen in a supersonic plasma jet, generated from an Ar-H (2) mixture, reveals an unexpected shock pattern. Whereas both the axial-velocity profile and the temperature profile of hydrogen atoms along the jet centerline can be interpreted in terms of a supersonic expansion of an Ar-H gas mixture, the H-atom density profiles do not satisfy the well established Rankine-Hugoniot relation leading to a nonconservation of the forward flux. The experimental results show that H atoms escape from the supersonic expansion by a diffusion process due to strong density gradients between the core of the jet and its vicinity.     

Influence of lipids on the interfacial disposition of respiratory syncytical virus matrix protein

The propensity of a matrix protein from an enveloped virus of the Mononegavirales family to associate with lipids representative of the viral envelope has been determined using label-free methods, including tensiometry and Brewster angle microscopy on lipid films at the air-water interface and atomic force microscopy on monolayers transferred to OTS-treated silicon wafers. This has enabled factors that influence the disposition of the protein with respect to the lipid interface to be characterized. In the absence of sphingomyelin, respiratory syncytial virus matrix protein penetrates monolayers composed of mixtures of phosphocholines with phosphoethanolamines or cholesterol at the air-water interface. In ternary mixtures composed of sphingomyelin, 1,2-dioleoyl-sn-glycero-3-phosphocholine, and cholesterol, the protein exhibits two separate behaviors: (1) peripheral association with the surface of sphingomyelin-rich domains and (2) penetration of sphingomyelin-poor domains. Prolonged incubation of the protein with mixtures of phosphocholines and phosphoethanolamines leads to the formation of helical protein assemblies of uniform diameter that demonstrate an inherent propensity of the protein to assemble into a filamentous form.