Biomedical subjects

Teruhiko Matsubara

Publications and source records attributed to Teruhiko Matsubara.

4 recordsLinked to original sources

PubMed2007

Specific binding of GM1-binding peptides to high-density GM1 in lipid membranes.

The ganglioside Galbeta1-3GalNAcbeta1-4(Neu5Acalpha2-3)Galbeta1-4Glcbeta1-1'Cer (GM1) is an important receptor. We have previously identified GM1-binding peptides based on affinity selection from a random peptide library. In the present study, we determined the amino acids essential for binding GM1 and investigated the specific interaction with GM1 in the lipid membrane. Arginines and aromatic amino acids in the consensus sequence (W/F)RxL(xP/Px)xFxx(Rx/xR)xP contributed to the ability of the peptides to bind GM1. The peptide p3, VWRLLAPPFSNRLLP, having the consensus sequence, showed high affinity for GM1 with a dissociation constant of 1.2 microM. Furthermore, the density-dependent binding of p3 was investigated using mixed monolayers of GM1 and Glcbeta1-1'Cer (GlcCer). p3 binds preferentially to high-density GM1, and its interaction with GM1 was found to be cooperative based on a Hill plot. These results indicated that a lateral assembly of GM1 molecules was required for the recognition of carbohydrates by p3. The GM1-binding peptide played a role as a unique anti-GM1 probe differing from the cholera toxin B subunit or antibodies.

Amino Acid Sequence↗

PubMed2006

Stability of protease in organic solvent: structural identification by solid-state NMR of lyophilized papain before and after 1-propanol treatment and the corresponding enzymatic activities.

Lyophilized enzyme powder is often used in organic solvents. However, the enzymatic activity decreases during the reaction process. In the present study, the relation between structural stability and enzymatic activity in an organic solvent was investigated. 13C cross-polarization magic angle spinning NMR spectroscopy was used to determine the secondary structure of lyophilized papain in the solid-state. Deconvolution of the peaks of the backbone carbonyl carbons suggested that the proportion of beta-sheet conformation increased after lyophilization from a phosphate buffer solution. The esterification of N-benzyloxycarbonyl phenylalanylalanine amide was attempted using the lyophilized papain as a catalyst in anhydrous 1-propanol. The yield of ester was 46.1% after 48 h at 50 degrees C, but this reaction slowed remarkably after 48 h. When the lyophilized papain was suspended in anhydrous 1-propanol for 7 days without the substrate, the proportion of beta-sheet conformation was further increased and the suspended papain had no activity. These results suggest that the increase in beta-sheet conformation caused inactivation of papain. The increase in beta-sheet conformation caused by both lyophilization and suspension in propanol was found, which was related to a decrease in enzymatic activity.

1-Propanol↗

PubMed2005

A peptide motif recognizing a polymer stereoregularity.

A combinatorial phage display method was applied to films composed of a stereoregular polymer of methacrylates. The phage clones with selective affinity for isotactic (it) poly(methyl methacrylate) (PMMA) were isolated. Greater amounts of the phage clones bound to it-PMMA, compared to other stereoregular PMMAs. The phage expressing ELWRPTR most strongly bound to the polymer, and the selectivity was also the best. The peptide motif essential for the specific interaction with the stereoregular polymer was revealed.

Amino Acid Motifs↗

PubMed2003

Selection of novel structural zinc sites from a random peptide library.

Zinc ion (Zn(2+)) can be coordinated with four or three amino acid residues to stabilize a protein's structure or to form a catalytic active center. We used phage display selection of a dodecamer random peptide library with Zn(2+) to identify structural zinc sites. The binding specificity for Zn(2+) of selected sequences was confirmed using enzyme-linked immunosorbent and competitive inhibition assays. Circular dichroism spectra indicated that the interaction with Zn(2+) induced a change in conformation, which means the peptide acts as a structural zinc site. Furthermore, a search of protein databases revealed that two selected sequences corresponded to parts of natural zinc sites of copper/zinc superoxide dismutase and zinc-containing ferredoxin. We demonstrated that Zn(2+)-binding sequences selected from the random combinatorial library would be candidates for artificial structural zinc sites.

Amino Acid Sequence↗