Spatial structure of the M2 transmembrane segment of the nicotinic acetylcholine receptor alpha-subunit.

A synthetic peptide corresponding to the transmembrane segment M2 (residues 236-267) of the alpha-subunit of the nicotinic acetylcholine receptor from Torpedo californica has been studied by two dimensional 1H-NMR spectroscopy in a chloroform-methanol (1:1) mixture containing 0.1 M LiClO4. Reconstruction of the spatial structure of M2 from the NMR data resulted in an alpha-helix formed by residues 241-263. Distribution of the molecular hydrophobicity potential on the helix surface is very similar to that in five-helix bundles of proteins with a known three dimensional structure: two hydrophilic bands located on the opposite helix sides separated by strong hydrophobic zones.

Tumor cell cytolysis mediated by valorphin, an opioid-like fragment of hemoglobin beta-chain.

Valorphin, an endogenous opioid-like hemoglobin fragment, is cytotoxic for L929 and K562 tumor cells in 10(-7)-10(-13) M concentration range. Because cytolytic effects induced by valorphin in K562 cells are inhibited by naloxone, opioid receptors should be involved in induction of valorphin-mediated tumor cell death. Three distinct cytolytic processes, differing in the onset time and the development time, take place with K562 cells within 10-18 h of incubation with valorphin. All three processes are not associated with apoptotic mechanism of cell death.

Localization of a sequential B-epitope in the VP2 protein of hepatitis A virus.

A set of synthetic peptides derived from the capsid protein of hepatitis A virus was used to search for B-epitopes. Peptides from the 115-139 region of the VP1 protein, from the 69-99 region of the VP2 protein and peptide 137-150 from the VP3 protein were found to react with monoclonal and polyclonal anti-HAV antibodies. MAPs based on 64-80 and 66-80 fragments of VP3 were reactive as well. Peptides, their conjugates with protein carriers and MAPs were used for antipeptide antibody production. Only free peptide 69-99 from the VP2 protein caused formation of HAV binding antibodies.

Synthetic peptides in the determination of hepatitis A virus T-cell epitopes.

Computer search for probable T-epitopes of hepatitis A virus capsid proteins was performed using an integrated set of programs. Eight segments of the VP1, VP2, VP3 and VP4 proteins were chosen and synthesised. Five peptides previously examined as probable B-epitopes were used as well. All the peptides were tested for their ability to stimulate proliferation of lymph node T-cells primed with synthetic peptides. Almost all predicted T-epitopes affected the T-cell proliferation. None of the peptides had mitogenic activity. We demonstrated that regions 17-33 and 276-298 of VP1 are possible immunodominant promiscuous sites activating lymphocytes of all mouse haplotypes.

Effective method for synthetic peptide immobilization that increases the sensitivity and specificity of ELISA procedures.

A procedure is described for the immobilization of synthetic peptide antigens on a plastic solid phase for performing ELISA. The use of a streptavidin-biotinylated peptide system for coating microplates with peptide antigen markedly increased both the sensitivity and the specificity compared to a standard ELISA based on synthetic peptides. The procedure was used for the detection of HIV-1-specific antibodies.

The synthetic peptide from HIV increases functional activity of granulocytes in healthy subjects.

The influence of HIV lysate and eight synthetic peptides which are fragments of HIV proteins on the functional activity of polymorphonuclear neutrophils (PMN) was tested in 12 healthy subjects. PMN activity in nitroblue tetrazolium reduction (NBT test) and PMN chemiluminescence (CL) was studied. Only one peptide was found to result in a significant increase in NBT test on the whole blood. This was the oligopeptide (G-97) from the CD4-binding site of HIV-1 gp120. The increase of CL response of PMN in the presence of G-97 was revealed after only 15 min preincubation. The same effect in the presence of sera from healthy or infected patients at the persistent generalized lymphadenopathy stage was achieved by increasing the time of preincubation to 30 min. G-97 did not influence the proliferative activity of lymphocytes.

Lassa virus glycoproteins: antigenic and immunogenic properties of synthetic peptides to GP1.

Synthetic peptides corresponding to predicted Lassa virus GP1 glycoprotein B-epitopes were used to study the antigenicity and immunogenicity of the protein. ELISA results showed that guinea pig polyclonal anti-Lassa virus serum bound effectively to peptides corresponding to amino acid residues 119-133 and 164-176 of the GP1 protein. Essentially it did not react to a peptide corresponding to GP1 amino acid residues 234-256. Sera obtained against peptides representing amino acid residues 119-133 and 164-176 reacted with inactivated purified Lassa virus.