Biomedical subjects

Y Kiho

Publications and source records attributed to Y Kiho.

At least 19 recordsLinked to original sources

PubMed1991

Binding of viral glycoprotein with trypsin and its relation to virulency. I. Initial step of binding.

The interaction between surface proteins of some enveloped viruses and trypsin was studied by computer analysis. Prior to the cleavage of the viral protein by trypsin, hydrophobic interaction between them at the vicinity of their active sites may occur. An exposed hydrophobic portion was found there which theoretically could stimulate the interaction. This interaction would be rather non-specific: according to the analysis, trypsin could bind equally well with weakly virulent virus and virulent viruses. Following this interaction, a specific reaction between their active sites would occur. The specificity was found to be related to the virulency of the virus.

Amino Acid Sequence↗

PubMed1991

Binding of viral glycoprotein with trypsin and its relation to virulency. II. Comparison between bovine and Streptomyces griseus trypsins.

The two step nature of the binding reaction between trypsin and viral glycoproteins was further investigated using two types of trypsin, bovine trypsin and Streptomyces griseus trypsin. The experimental results were explained by the van der Waals energy operating in the second step, suggesting that the conformational aspects, in addition to the electrostatic nature, of the interacting peptides are decisive in this specific process.

Amino Acid Sequence↗

PubMed1991

Protein folding: construction of functional structure.

The problem of protein folding was studied with trypsin inhibitor by deviation analysis (1). The results showed that: i) Qualitatively, the main features of the structure, determined by this method, coincided with the structure determined by X-ray crystallography (3). This structure is, however, not topological but functional, and may elucidate the functional relations between various parts of the protein.

Amino Acid Sequence↗

PubMed1991

Functional structure of protein: exposed vs hidden function.

The dev analysis was used to construct the functional structure of protein (3). Based on this principle, the intramolecular interaction of dev peak was investigated. Two types of peak were observed: one is the hidden peak which interacts strongly with another region of the molecule and the other is the exposed peak whose interaction was weak. Analysis was made with trypsin and its inhibitor and on the intermolecular interaction between their exposed peaks. One interaction between their exposed peaks was found to coincide with one which had been already known to be authentic between their active sites.

Amino Acid Sequence↗

PubMed1989

Prediction of the virulencies of some enveloped viruses from the structure of the cleavage recognition site of viral glycoproteins essential for infectivity. I. Calculation of interaction energy.

Some evidences have been found that virulency in paramyxoviruses depends on the sensitivity of the cleavage recognition site of the F glycoprotein to serine type proteases. In this report, the interaction energies between the active site of trypsin and the cleavage recognition sites in paramyxoviruses are calculated. Results show that van der Waals energy and electrostatic energy contribute to the sensitivity. The virulencies of some myxo- and retro-viruses are then predicted on the basis of the two calculated interaction energy values.

Amino Acid Sequence↗

PubMed1989

Prediction of the virulencies of some enveloped viruses from the structure of the cleavage recognition site of viral glycoprotein essential for infectivity. II. Deviation analysis.

Analysis of the amino acid sequence in protein (deviation analysis) suggests that the binding between trypsin and the enveloped virus is the first step of their interaction, which occurs in a specified configuration. It is possible that the distance between their active sites is important for the viral sensitivity to trypsin, which is related to the virulency of the enveloped virus.

Amino Acid Sequence↗

PubMed1988

Antibodies to Asp-Asp-Glu-Asp can inhibit transport of nuclear proteins into the nucleus.

The signal sequence of simian virus 40 (SV40) large T-antigen for translocation into the nucleus is composed of positively charged amino acids Lys-Lys-Lys-Arg-Lys. Rabbit antibodies to a synthetic peptide containing the negatively charged amino acid sequence Asp-Asp-Asp-Glu-Asp were obtained. Indirect immunofluorescence of the antigens recognized by the antibody was punctate at the nuclear rim or the nuclear surface, depending on the plane of focus. The antibody blocked transport of nuclear proteins into the nucleus. The antigens recognized by the antibody were predominantly localized to the nuclear pores.

Amino Acid Sequence↗

PubMed1988

Regional variation and function of nucleotide and amino acid sequence.

Two methods of qualitative analysis of sequence distribution in DNA and protein are presented. The first method is based on the finding that the frequency of occurrence of each nucleotide in a defined sequence with functional significance more or less deviates from uniform distribution. The deviation found in this defined sequence seems to parallel the function of this sequence. In the second method, two model compounds (trypsin and its inhibitor) have been used to see the topological fit between their local structures. Acrophilicity parameter for amino acid was used to construct the topological structure. Both methods may find practical application in algorithms to design functional DNA and protein molecules.

Algorithms↗

PubMed1985

Molecular basis of plant viral virulence; the complete nucleotide sequence of an attenuated strain of tobacco mosaic virus.

The total genome sequence of L11A, an attenuated strain of tobacco mosaic virus (TMV), has been determined. This strain is able to multiply in tomato plants without inducing any remarkable symptoms, but to protect them from later infection with virulent TMV strains. When compared with the recently published total genome sequence of TMV L (the virulent ancestral strain of L11A) ten base substitutions were found in the L11A genome. Seven of these occurred in the third letters of in-phase codons and did not influence amino acids. Only three, which were in the common reading frame for both the 130K and 180K proteins, resulted in amino acid changes. Together with the result of the partial sequence of RNA of L11, an intermediate strain in sequential isolation from L to L11A, it is observed that one base at the nucleotide position 1117 is changed from L to L11 and two bases at the positions 2349 and 2754 are changed from L11 to L A11.

Amino Acid Sequence↗

PubMed1979

Infectivity suppressing and virus-binding activities of a membrane material isolated from tobacco leaves.

TMV binding substance (R) was isolated from a tobacco leaf membrane fraction and was purified by extraction with organic solvents and by column chromatography. Experimental results suggest that the binding of R with TMV results in inactivation of TMV. When tobacco leaves were inoculated with the R-TMV complex, it was found that the formation of polysome containing infecting viral RNA was inhibited. Model experiments showed that the mode of R-TMV adsorption to the membrane is different from that of TMV adsorption and that stripping of coat protein from TMV by SDS was inhibited by R. A possible explanation for the mechanism of this inhibition by R is that the R-TMV complex follows a pathway which does not lead to establishment of infection. Although less efficient, R was still active when it was applied after virus inoculation. Due to its affinity to coat protein, R might also interfere with a later process of viral multiplication.

Adsorption↗

PubMed1979

Disassembly of tobacco mosaic virus by membrane lipid isolated from tobacco leaves and polyornithine.

In vitro disassembly of tobacco mosaic virus (TMV) virions occurred in the presence of both polyornithine and a lipid fraction isolated from tobacco leaf membrane. The latter could be replaced by lecithine. Disassembly of 10 microgram of TMV virions was attained in the presence of a 500-mg leaf equivalent of membrane lipid and 20 microgram of polyornithine in 1 ml of 0.01 M Tris-HCl buffer, pH 7.4 at 30 C. Similarity and dissimilarity between the in vitro disassembly and the in vivo uncoating mechanisms are discussed.

Membrane Lipids↗

PubMed1976

Binding of tobacco mosaic virus to membrane material isolated from tobacco leaves.

Binding of tobacco mosaic virus (TMV) to disrupted tobacco leaf membrane was studied. Membrane isolated from tobacco leaves was treated successively with (NH4)2SO4, Li-diiodosalicylate and then pronase. TMV-binding substance was thus isolated in a soluble form. From enzymatic digestion experiments, it was suggested that the binding substance was composed of lipid and carbohydrate.

Adsorption↗

PubMed1974