Biomedical subjects

K Vlahovicek

Publications and source records attributed to K Vlahovicek.

12 recordsLinked to original sources

PubMed2003

Design of peptide mimetics of HIV-1 gp120 for prevention and therapy of HIV disease.

It has been reported that the C-terminus of the second conserved region (C2) of the envelope glycoprotein gp120, encompassing peptide RSANFTDNAKTIIVQLNESVEIN (NTM), is important for infectivity and neutralization of the human immunodeficiency virus type 1 (HIV-1). It was also demonstrated that human natural anti-vasoactive intestinal peptide (VIP) antibodies reactive with this gp120 region play an important role in control of HIV disease progression. The bioinformatic analysis based on the time-frequency signal processing revealed non-obvious similarities between NTM and VIP. When tested against a battery of sera from 46 AIDS patients, these peptides, in spite of a significant difference in their primary structures, showed a similar reactivity profiles (r = 0.83). Presented results point out that similarity in the periodical pattern of some physicochemical properties in primary structures of peptides plays a significant role in determination of their immunological crossreactivity. Based on these findings, we propose this bioinformatic criterion be used for design of VIP/NTM peptide mimetics for prevention and treatment of HIV disease.

Amino Acid Sequence↗

PubMed2001

The SBASE protein domain library, release 8.0: a collection of annotated protein sequence segments.

SBASE 8.0 is the eighth release of the SBASE library of protein domain sequences that contains 294 898 annotated structural, functional, ligand-binding and topogenic segments of proteins, cross-referenced to most major sequence databases and sequence pattern collections. The entries are clustered into over 2005 statistically validated domain groups (SBASE-A) and 595 non-validated groups (SBASE-B), provided with several WWW-based search and browsing facilities for online use. A domain-search facility was developed, based on non-parametric pattern recognition methods, including artificial neural networks. SBASE 8.0 is freely available by anonymous 'ftp' file transfer from ftp.icgeb.trieste.it. Automated searching of SBASE can be carried out with the WWW servers http://www.icgeb.trieste.it/sbase/ and http://sbase.abc. hu/sbase/.

Binding Sites↗

PubMed2001

Prediction of protein functional domains from sequences using artificial neural networks.

An artificial neural network (ANN) solution is described for the recognition of domains in protein sequences. A query sequence is first compared to a reference database of domain sequences by use of and the output data, encoded in the form of six parameters, are forwarded to feed-forward artificial neural networks with six input and six hidden units with sigmoidal transfer function. The recognition is based on the distribution of scores precomputed for the known domain groups in a database versus database comparison. Applications to the prediction of function are discussed.

Computational Biology↗

PubMed2000

The SBASE protein domain library, release 7.0: a collection of annotated protein sequence segments.

SBASE 7.0 is the seventh release of the SBASE protein domain library sequences that contains 237 937 annotated structural, functional, ligand-binding and topogenic segments of proteins, cross-referenced to all major sequence databases and sequence pattern collections. The entries are clustered into over 1811 groups and are provided with two WWW-based search facilities for on-line use. SBASE 7.0 is freely available by anonymous 'ftp' file transfer from ftp.icgeb. trieste.it. Automated searching of SBASE with BLAST can be carried out with the WWW servers http://www.icgeb.trieste.it/sbase/and http://sbase.abc.hu/sbase/

Amino Acid Sequence↗

PubMed2000

Model.it: building three dimensional DNA models from sequence data.

UNLABELLED: A WWW server is described for creating 3D models of canonical or bent DNA starting from sequence data. Predicted DNA trajectory is first computed based on a choice of di- and tri-nucleotide models (M.G. Munteanu et al., Trends Biochem. Sci. 23, 341-347, 1998); an atomic model is then constructed and optionally energy-minimized with constrained molecular dynamics. The data are presented as a standard PDB file, directly viewable on the user's PC using any molecule manipulation program. AVAILABILITY: The model.it server is freely available at http://www.icgeb.trieste.it/dna/ CONTACT: kristian@icgeb.trieste.it; pongor@icgeb.trieste.it SUPPLEMENTARY INFORMATION: a series of help files is available at the above address.

Base Sequence↗

PubMed2000

A simple probabilistic scoring method for protein domain identification.

SUMMARY: A simple heuristic scoring method is described for assigning sequences to known domain types based on BLAST search outputs. The scoring is based on the score distribution of the known domain groups determined from a database versus database comparison and is directly applicable to BLAST output processing.

Computational Biology↗

PubMed1999

The SBASE protein domain library, release 6.0: a collection of annotated protein sequence segments.

The sixth release of the SBASE protein domain library sequences contains 130 703 annotated and crossreferenced entries corresponding to structural, functional, ligand-binding and topogenic segments of proteins. The entries were grouped based on standard names (2312 groups) and futher classified on the basis of the BLAST similarity (2463 clusters). Automated searching with BLAST and a new sequence-plot representation of local domain similarities are available at the WWW-server http://www.icgeb.trieste.it/sbase. A mirror site is at http://sbase.abc.hu/sbase. The database is freely available by anonymous 'ftp' file transfer from ftp.icgeb.trieste.it

Amino Acid Sequence↗

PubMed1999

Sequence-dependent modelling of local DNA bending phenomena: curvature prediction and vibrational analysis.

Bending is a local conformational micropolymorphism of DNA in which the original B-DNA structure is only distorted but not extensively modified. Bending can be predicted by simple static geometry models as well as by a recently developed elastic model that incorporate sequence dependent anisotropic bendability (SDAB). The SDAB model qualitatively explains phenomena including affinity of protein binding, kinking, as well as sequence-dependent vibrational properties of DNA. The vibrational properties of DNA segments can be studied by finite element analysis of a model subjected to an initial bending moment. The frequency spectrum is obtained by applying Fourier analysis to the displacement values in the time domain. This analysis shows that the spectrum of the bending vibrations quite sensitively depends on the sequence, for example the spectrum of a curved sequence is characteristically different from the spectrum of straight sequence motifs of identical basepair composition. Curvature distributions are genome-specific, and pronounced differences are found between protein-coding and regulatory regions, respectively, that is, sites of extreme curvature and/or bendability are less frequent in protein-coding regions. A WWW server is set up for the prediction of curvature and generation of 3D models from DNA sequences (http:@www.icgeb.trieste.it/dna).

Base Sequence↗

PubMed1999

The domain-server: direct prediction of protein domain-homologies from BLAST search.

RESULTS: A WWW server for protein domain homology prediction, based on BLAST search and a simple data-mining algorithm (Hegyi,H. and Pongor,S. (1993) Comput. Appl. Biosci., 9, 371-372), was constructed providing a tabulated list and a graphic plot of similarities. AVAILABILITY: http://www.icgeb.trieste.it/domain. Mirror site is available at http://sbase.abc.hu/domain. A standalone programme will be available on request. SUPPLEMENTARY INFORMATION: A series of help files is available at the above addresses.

Algorithms↗

PubMed1998

Rod models of DNA: sequence-dependent anisotropic elastic modelling of local bending phenomena.

Local bending phenomena can be predicted by elastic models that incorporate sequence-dependent anisotropic-bendability (SDAB). SDAB models consider DNA to be an initially straight, segmented, elastic rod, in which the flexibility of each segment is greater towards the major groove than it is in other directions. While local bending can be predicted by static-geometry models as well, SDAB models, in addition, qualitatively explain such phenomena as the affinity of protein binding and kinking. A set of prediction tools is available at http:/(/)www.icgeb.trieste.it/dna.

Animals↗

PubMed1997

Distribution of sequence-dependent curvature in genomic DNA sequences.

The distribution of inherent, sequence-dependent curvature was calculated for a number of prokaryotic (M. genitalium, H. influenzae, M. jannaschii), viral (adenovirus 2, equine herpes virus 1), phage (M13, lambda), eukaryotic (S. cerevisiae) and mitochondrial genomes as well as E. coli and human genomic fragments. The genomic averages are in the range of 6-8 degrees/helical turn and only about 20% of DNA is curved less than 3 degrees/helical turn. The prokaryotes and phages appear to have a consistently higher frequency of curved DNA in their genomes than the other genomes tested. Long, highly curved segments, similar to artificially designed curved DNA, are apparently absent from the genomes. Short, curved segments, differing in G+C content may provide environmentally modulated conformational signals for gene regulation. A WWW-server was constructed for the prediction of curved sites from DNA sequences (http://icgeb.trieste.it/dna/curve_it.html/)..

Animals↗

PubMed1997

The SBASE protein domain library, release 5.0: a collection of annotated protein sequence segments.

SBASE 5.0 is the fifth release of SBASE, a collection of annotated protein domain sequences that represent various structural, functional, ligand-binding and topogenic segments of proteins. SBASE was designed to facilitate the detection of functional homologies and can be searched with standard database-search programs. The present release contains over 79863 entries provided with standardized names and is cross-referenced to all major sequence databases and sequence pattern collections. The information is assigned to individual domains rather than to entire protein sequences, thus SBASE contains substantially more cross-references and links than do the protein sequence databases. The entries are clustered into >16 000 groups in order to facilitate the detection of distant similarities. SBASE 5.0 is freely available by anonymous 'ftp' file transfer from . Automated searching of SBASE with BLAST can be carried out with the WWW-server . and with the electronic mail server which now also provides a graphic representation of the homologies. A related WWW-server and e-mail server predicts SBASE domain homologies on the basis of SWISS-PROT searches.

Amino Acid Sequence↗