Search PubMed⌕ Search

Biomedical subjects

H Minakata

Publications and source records attributed to H Minakata.

At least 91 records · Page 5Linked to original sources
PubMed1991

Effects of the neuropeptide APGW-amide and related compounds on molluscan muscles--GW-amide shows potent modulatory effects.

1. Effects of the molluscan neuropeptide APGW-amide and related compounds (the crustacean hormone RPCH, FAPGW-amide, PGW-amide, GW-amide and W-amide) were examined in several kinds of molluscan muscles. 2. All the compounds, except W-amide, showed qualitatively similar modulatory effects on contraction or relaxation of the muscles. The potency order of the compounds was found to be GW-amide greater than or equal to APGW-amide greater than FAPGW-amide greater than RPCH greater than PGW-amide. W-amide showed little or no effect even at 10(-4) M. 3. In the ABRM of Mytilus and the radula retractor muscle of Rapana, the active peptides were suggested to exhibit their modulatory effects by acting on the presynaptic sites in the muscles. 4. Nineteen GW-amide analogues, such as Gly-Trp-OH, Gly-Phe-NH2, D-Ala-Trp-NH2 and N-Gly-tryptamine, were also tested on some of the muscles, but all of them showed little or no effect.

Animals↗
PubMed1991

Isolation of achatin-I, a neuroactive tetrapeptide having a D-phenylalanine residue, from Achatina ganglia, and its effects on Achatina giant neurones.

1. We have isolated a neuroexcitatory tetrapeptide having a D-phenylalanine (Gly-D-Phe-L-Ala-L-Asp) from the ganglia of Achatina fulica Férussac. This peptide was termed achatin-I (Kamatani et al., 1989). In the present report, we shall present highlights from the original paper concerning the process of peptide isolation and the examination of its effects. 2. From the ganglia of about 30,000 animals, we obtained 50 micrograms of achatin-I and 17 micrograms of its stereoisomer consisting of only L-amino acid residues (Gly-L-Phe-L-Ala-L-Asp) which was termed achatin-II. The data of instrumental analyses (1H-NMR, SIMS, CD and HPLC) of isolated achatin-I and achatin-II were identical to those of synthetic ones. 3. Achatin-I showed marked excitatory effects on the three Achatina giant neurones, PON (periodically oscillating neurone), TAN (tonically autoactive neurone) and v-RCDN (ventral-right cerebral distinct neurone), whereas achatin-II had no effect. Among their stereoisomers, [D-Ala3]-achatin-I (Gly-D-Phe-D-Ala-L-Asp) had slight excitatory effects on the Achatina neurones tested. Amide derivatives of achatin-I and achatin-II were ineffective. 4. Dose-response curves of achatin-I and [D-Ala3]-achatin-I for producing the inward current of PON were measured under voltage clamp at a holding membrane voltage (Vh) of -50 mV.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1991

A variety of Mytilus inhibitory peptides in the ABRM of Mytilus edulis: isolation and characterization.

1. Five species of Mytilus inhibitory peptides, MIP1-5, were isolated from acetone extracts of the anterior byssus retractor muscle (ABRM) of Mytilus edulis. MIP1 and MIP2 were shown to be S2-MIP and A2-MIP, respectively, first isolated from the pedal ganglia of the animal. 2. All the five peptides had a common C-terminal structure of -Pro-Xaa-Phe-Val-NH2, which was shown to be important for their biological activity. 3. The five MIPs showed similar inhibitory effects on contractions of the ABRM but did not affect catch tension and its relaxation. 4. In addition to the MIPs, catch-relaxing peptide (CARP) was also found in the ABRM.

Amino Acid Sequence↗
PubMed1990

Molecular conformation of achatin-I, an endogenous neuropeptide containing D-amino acid residue. X-ray crystal structure of its neutral form.

The molecular conformation of achatin-I neutral form (H-Gly-D-Phe-Ala-Asp-OH), an endogenous neuropeptide, was elucidated by X-ray crystal analysis. The molecule has a type II' beta-turn structure with the D-Phe-Ala residues at the corner of the bend, which is further stabilized by two NH(Gly)...C gamma = O sigma(Asp) and NH(Asp)...C gamma = O sigma(Asp) intramolecular hydrogen bonds. This turn conformation may be an important feature of achatin-I related to its neuroexcitatory activity.

Amino Acid Sequence↗
PubMed1990

Synthesis of analogues of peptide YY with modified N-terminal regions: relationships of amphiphilic secondary structures and activity in rat vas deferens.

Peptide YY (PYY) not only has distinct sequence homology with neuropeptide Y (NPY) and avian pancreatic polypeptide (APP), but it also exhibits both NPY- and APP-like biological activities. We synthesized two analogues of PYY, A1 and A2, with modified N-terminal regions, and compared their chemical and biological properties to those of PYY and the C-terminal fragment of PYY, (13-36)PYY. This study shows that there is a good correlation between the stability of amphiphilic alpha-helical structure and the biological activity of these peptides. A CD study of (13-36)PYY in mixed H2O and trifluoroethanol (TFE) solutions indicated a significant increase in alpha-helical segments (26-79%) with increasing TFE proportions. Since the fragment (13-36)PYY had potent activity in the rat vas deferens (RVD) assay, the secondary structure is possibly required on the RVD cell surface receptors. The analogues, A1 and A2, were designed to increase the stability of the alpha-helical structures by incorporation of modified N-terminal regions. The CD studies and the RVD assays of A1 and A2, suggest that the amphiphilic alpha-helical structures are stabilized by intramolecular hydrophobic interactions with the N-terminal regions and/or by intermolecular hydrophobic interactions in the self-association process, and subsequently potentiate the activities of the peptides compared to those of PYY and (13-36)PYY.

Amino Acid Sequence↗
PubMed1989

Achatin-I, an endogenous neuroexcitatory tetrapeptide from Achatina fulica Férussac containing a D-amino acid residue.

A tetrapeptide named achatin-I was purified from the suboesophageal and cerebral ganglia of the African giant snail Achatina fulica Férussac, and evoked a potent neuroexcitatory effect. The amino acid sequence of achatin-I is Gly-D-Phe-Ala-Asp. Achatin-I induced a voltage-dependent inward current, due to Na+, on the identifiable giant neuron, periodically oscillating neuron (PON), of the same snail. All possible isomers of achatin-I were synthesized using the solid-phase method. The sensitivity of the neuron to achatin-I and its isomers was strictly stereospecific; among the various isomers, only achatin-I showed marked effects (ED50 = 2.29 x 10(-6)M), while Gly-D-Phe-D-Ala-Asp, the synthetic D-Ala-isomer, was less than 10(-3) active.

Amino Acid Sequence↗
PubMed1989

Characterization of amphiphilic secondary structures in neuropeptide Y through the design, synthesis, and study of model peptides.

Neuropeptide Y (NPY) has the potential to form two amphiphilic secondary structures: a polyproline II-like helix in residues 1-8, and an alpha-helix in residues 13-32. NPY dimerizes in aqueous solution and forms stable monolayers at the air-water interface, suggesting that these amphiphilic conformations are stabilized at interfaces. Furthermore, the negative molar ellipticity of monomeric NPY at 222 nm (-8500 degree cm2/dmol), suggests that hydrophobic interactions with the NH2-terminal amphiphilic structure may stabilize the alpha-helix in residues 13-32 before it binds to cell surfaces, even at physiological concentrations. In order to investigate the role of these amphiphilic structures, five NPY models with multiple substitutions in positions 13-32 have been synthesized and studied. Our data demonstrate that the surfactant properties of NPY result from its potential to form amphiphilic secondary and tertiary structures and not from specific amino acid sequences in this region. However, specific residues on the hydrophilic face of the amphiphilic alpha-helix that have been substituted in the models appear to be required to reproduce the full potency of NPY in our pharmacological assays. A possible role for the amphiphilic structures in NPY in presenting such specific determinants to cell surface receptors in the correct conformation is suggested.

Amino Acid Sequence↗
PubMed1985

Antimutagenic unusual amino acids from plants.

Five unusual amino acids were identified as antimutagens against spontaneous mutation of Salmonella typhimurium TA100: L-azetidine-2-carboxylic acid (1) from Liliaceae plants, alpha-(methylenecyclopropyl)glycine (2) from Litchi chinensis seeds, and 2-amino-4-methylhex-5-ynoic acid (3), hypoglycin A (4), and (2S,4R)-2-amino-4-hydroxyhept-6-ynoic acid (5) from Euphoria longana seeds. The absolute stereochemistry of 5 was determined by its chiral synthesis from L-allylglycine, proving that 5 is the C-4 epimer of the amino acid previously isolated from dried longan seeds.

Amino Acids↗