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Biomedical subjects

H Minakata

Publications and source records attributed to H Minakata.

At least 55 records · Page 3Linked to original sources
PubMed1995

Isolation and characterization of opioid peptides in the avian brain.

Neuropeptides are supposed to be implicated in the regulation of hormone as well as nonhormone dependent behavioral processes in birds. Previous immunohistochemical studies have suggested that in birds opioid pentapeptides, Met- and Leu-enkephalins, may be present in the brain including the regions that regulate sex hormone dependent behaviors, such as reproductive behaviors. To determine biochemically the presence of opioid peptides in the avian brain, a study was conducted to isolate these peptides from Japanese quails and zebra finches. Acetic acid extracts of the quail and finch brains were respectively forced through disposable C-18 reversed-phase cartridges, and then the retained material was subjected to the cation-exchange and reversed-phase high performance liquid chromatographic (HPLC) purifications. All of the purified substances showed a single peak on the reversed-phase HPLC and these substances enhanced spontaneous contractions of the avian rectum. The purified bioactive substances were further subjected to amino acid sequence analysis and were characterized as peptides with the following sequences: Tyr-Gly-Gly-Phe-Met, Tyr-Gly-Gly-Phe-Leu, and Tyr-Gly-Gly-Phe-Met-Arg-Phe. These three peptides were identical with opioid pentapeptides, Met- and Leu-enkephalins, and a heptapeptide, Met-enkephalin-Arg6-Phe7, which had been previously isolated from mammalian species. This is the first direct demonstration of the presence of opioid peptides in the avian brain and confirms previous immunohistochemical findings suggesting a functional role for the opioid peptide in neural mechanisms of avian reproductive behavior.

Amino Acid Sequence↗
PubMed1995

Effects of annetocin, an oxytocin-related peptide isolated from the earthworm Eisenia foetida, and some putative neurotransmitters on gut motility of the earthworm.

Annetocin, an oxytocin-related peptide recently isolated from the lumbricid earthworm Eisenia foetida, and putative transmitter substances were examined for their effects on rhythmic, spontaneous contractions of isolated gut preparations of the earthworm. Significant, dose-dependent effects of the following substances were observed: acetylcholine (ACh), gamma-aminobutyric acid (GABA), and dopamine were excitatory, while serotonin (5-HT) and octopamine were inhibitory. Annetocin, oxytocin, and vasotocin stimulated spontaneous contraction of the earthworm gut, annetocin being approximately 10-fold more potent than oxytocin or vasotocin. However, arginine-vasopressin (Arg-vasopressin), lysine-vasopressin (Lys-vasopressin), tocinoic acid (N-terminal hexapeptide fragment of oxytocin), and MSH release-inhibiting factor (MIF; C-terminal tripeptide fragment of oxytocin) did not show any effect on the earthworm gut motility. On the other hand, oxytocin, vasotocin, Arg-vasopressin, Lys-vasopressin, and tocinoic acid caused spontaneous contractions of isolated rat uterine preparations, where the potency was in this order, while annetocin and MIF exerted no oxytocic activity on the uterus. Dose-response relationship of the effects of annetocin and its related peptides on the annelid and mammalian systems shows that amino acid residue at the third position of these peptides is important for exertion of excitatory action on the smooth muscle systems. The results in the present study suggest that receptors for annetocin and for GABA on the earthworm gut, unlike those for ACh, desensitize during continuous exposure to these substances.

Amino Acid Sequence↗
PubMed1995

Identification of Kk-restricted T-cell epitope within influenza virus nucleoprotein.

In order to determine the epitope structure in peptide NP50-63, which has been reported to be the only Kk-restricted T-cell antigen within the influenza virus (A/PR/8/34) nucleoprotein, a series of 13 peptides truncated from C- and N-termini of NP50-63 were synthesized and their sensitizing activities against Kk-restricted nucleoprotein-specific cytotoxic T lymphocytes (CTLs) were examined. One of the 13 peptides, NP50-57, sensitized L929 cells at the nM level, which was 100-1000 times lower in concentration than that at which the other peptides sensitized these cells. The presence of NP50-57 in A/PR/8/34-infected L929 cells was also investigated. Acid extracts of virus-infected cells were separated on a reverse-phase HPLC column and then anion-exchange column. By both separations, only one peak of sensitizing activity against nucleoprotein-specific CTLs was observed. The position of the peak coincided with that of the elution of NP50-57. These results strongly suggest that NP50-57 is the natural epitope in the antigenic structure, NP50-63.

Amino Acid Sequence↗
PubMed1995

Structure-activity relations of fulicin, a peptide containing a D-amino acid residue.

Structure-activity relations of fulicin (H-Phe-D-Asn-Glu-Phe-Val-NH2) isolated from the ganglia of a pulmonate mollusc Achatina fulica were investigated on the contraction of penis retractor muscle of this snail. The contraction-enhancing activity of fulicin was reduced to about 1/3000 when D-Asn2 was replaced by L-Asn, whereas substitution of the other D-amino acid for D-Asn2 showed no significant reduction of the activity. On the contrary, if a D-amino acid was introduced into any position other than position 2 the activity was reduced remarkably. The presence of Glu3 and five amino acid residues as a whole were also required for activity.

Amino Acid Sequence↗
PubMed1995

A novel gut tetradecapeptide isolated from the earthworm, Eisenia foetida.

A novel bioactive tetradecapeptide, GFKDGAADRISHGFamide, was isolated from the gut of the oligochaete annelid, Eisenia foetida, using the isolated anterior gut (crop-gizzard) as a bioassay system. A highly homologous peptide, GFRDGSADRISHGFamide, was also purified from the whole body of another species of earthworm, Pheretima vittata. These peptides were termed Eisenia tetradecapeptide (ETP) and Pheretima tetradecapeptide (PTP), respectively. Both the peptides showed a potent excitatory action on spontaneous contractions of the anterior gut with a threshold as low as 10(-10)-10(-9) M. These peptides were significantly homologous to molluscan tetradecapeptides and, to a lesser extent, to arthropodan tridecapeptides that have been reported to date. All these peptides seem to be evolutionally related to each other.

Amino Acid Sequence↗
PubMed1995

Isolation and characterization of four novel bioactive peptides from a polychaete annelid, Perinereis vancaurica.

Four bioactive peptides were purified from an extract of the polycheate annelid Perinereis vancaurica using an HPLC system for fractionation of the extract and the esophagus of the worm as bioassay system. The sequences of the peptides were determined to be H-Trp-Val-Val-Gly-Asp-Val-Gln-OH, H-Ala-Thr-Trp-Leu-Asp-Thr-OH, H-Trp-Met-Val-Gly-Asp-Val-Gln-OH and H-Phe-Tyr-Glu-Gly-Asp-Val-Pro-Tyr-OH. These peptides showed an excitatory activity on the esophagus of P. vancaurica. The excitatory effect of the second and fourth peptides was marked. They may be neuropeptides involved in regulation of the esophagus.

Amino Acid Sequence↗
PubMed1995

A novel cDNA sequence encoding the precursor of the D-amino acid-containing neuropeptide fulicin and multiple alpha-amidated neuropeptides from Achatina fulica.

Fulicin (Phe-D-Asn-Glu-Phe-Val-NH2) is an endogenous neuropeptide containing a D-amino acid from ganglia of the African giant snail Achatina fulica. We have cloned a novel cDNA (1,995 nucleotides) encoding a fulicin precursor from the snail cerebral and subesophageal ganglia. The fulicin precursor protein (357 amino acids) contains one copy of fulicin and at least nine other putative alpha-amidated neuropeptides composed of four to six amino acid residues. Seven of the nine neuropeptides were novel, and the other two had the same structures as Mytilus inhibitory peptide-related peptides previously isolated from the ganglia of Helix pomatia. All sequences of 10 peptides are flanked by Lys-Arg(Lys) at the N-terminus and by Gly-Lys-Arg(Lys) at the C-terminus. Nucleotide sequence analysis revealed that D-Asn present in fulicin is encoded by the usual L-Asn codon (AAT). Although fulicin has as yet only been isolated from the central ganglia. RNA blot analysis revealed that single transcripts of approximately 2.0 kb in size also exist in the ventricles and atria. These results suggest that fulicin and related peptides are produced in neurons and the heart by the processing of a ribosomally made precursor, although the mechanism of in-chain epimerization remains unclear.

Amino Acid Sequence↗
PubMed1995

Cloning, sequencing, and heterologous expression of a gene coding for Arthromyces ramosus peroxidase.

To understand the relationship between the structure and functions of the peroxidase of Arthromyces ramosus, a novel taxon of hyphomycete, and the evolutionary relationship of the A.ramosus peroxidase (ARP) with the other peroxidases, we isolated complementary and genomic DNA clones encoding ARP and characterized them. The sequence analyses of the ARP and cDNA coding for ARP showed that a mature ARP consists of 344 amino acids with a N-terminal pyroglutamic acid preceded by a signal peptide of 20 amino acid residues. The amino acid sequence of ARP was 99% identical to that of the peroxidase of Coprinus cinereus, a basidiomycete, and also had very high similarities (41-43% identity) to those of basidiomycetous lignin peroxidases, although we could find no lignin peroxidase activities for ARP when assayed with lignin model compounds. We could identified His184 and His56 as proximal and distal ligands to heme, respectively, and Arg52 as an essential Arg. Comparison of the sequences of complementary and genomic DNAs found that protein-encoding DNA is interrupted by 14 intervening sequences. The ARP cDNA was expressed in the yeast Saccharomyces cerevisiae under the promoter of the glyceraldehyde 3-phosphate dehydrogenase gene, yielding 0.02 units/ml of a secreted active peroxidase.

Base Sequence↗
PubMed1994

Annetocin: an oxytocin-related peptide isolated from the earthworm, Eisenia foetida.

An oxytocin-vasopressin-related peptide, Cys-Phe-Val-Arg-Asn-Cys-Pro-Thr-Gly-NH2, was isolated from the lumbricid earthworm, Eisenia foetida and termed annectocin. Annetocin potentiated not only spontaneous contractions of the gut but also pulsatory contractions and bladder-shaking movement of the nephridia. Annetocin may be involved in osmoregulation of the animal through nephridial function.

Amino Acid Sequence↗
PubMed1994

Silkworm diapause hormone, structure-activity relationships indispensable role of C-terminal amide.

To determine the structure-activity relationships of the silkworm diapause hormone, a series of peptide analogs having different chain lengths starting from the parent C-terminus and analogs having identical sequences with free acid C-termini were chemically synthesized by solid-phase Fmoc methodology and were further purified by HPLC. Bioassay showed that the analogs with free acid C-termini were non active. The retained activities of those shorter chains were shown only with the amidated C-terminal analogs among which the potency depended on the length of the chain. The active peptides required two minimal elements; namely the sequence near and the amidation of the C-terminus. There was no difference in enzymatic digestion of the C-terminally amidated or free acid analogs in pupal haemolymph. Hence the absence of DH activity of the free acid analogs was not because of being selectively hydrolyzed faster than the C-terminally amidated peptides. This suggested that existence of a certain higher order structure could be involved in expressing hormonal activity, or that the negative charge of the free acid terminus may be deleterious to a proper ligand receptor interaction. Since most of the hydrophobic amino acids were located near the C-terminal portion, both the hydrophobicity of the portion near and the amidation of the C-terminus were indispensable structures for diapause hormone activity.

Amides↗
PubMed1994

A myomodulin-CARP-related peptide isolated from a polychaete annelid, Perinereis vancaurica.

Myomodulin-CARP-family peptides have been isolated only from molluscs. In the present study, a heptapeptide, Ala-Met-Gly-Met-Leu-Arg-Met-NH2, termed Pev-myomodulin, was isolated from a polychaete annelid, Perinereis vancaurica using the esophagus of the animal as the bioassay system. The sequence of the annelid peptide is highly homologous with those of the myomodulin-CARP-family peptides found in molluscs. The annelid peptide is regarded as a member of the myomodulin-CARP family, though all the molluscan peptides have a Leu-NH2 at their C-termini. The annelid peptide showed a potnet contractile action on the esophagus of the annelid. The peptide may be an excitatory neuromediator involved in the regulation of the esophagus. Among various myomodulin-CARP-family peptides and their analogues, the annelid peptide showed the most potent contractile action on the esophagus. Replacement of the C-terminal Met-NH2 of the annelid peptide with a Leu-NH2 decreased its contractile potency, while replacement of the C-terminal Leu-NH2 of myomodulin and CARP with a Met-NH2 increased their potency. The C-terminal Met-NH2 of the annelid peptide seems to be important, but not essential, for exhibiting its contractile activity on the esophagus. On the anterior byssus retractor muscle of the bivalve mollusc Mytilus edulis, the annelid peptide showed catch-relaxing and contraction-modulating effects qualitatively similar to those of the authentic peptide CARP, though the annelid peptide was less potent than CARP.

Amino Acid Sequence↗
PubMed1993

WWamide-1, -2 and -3: novel neuromodulatory peptides isolated from ganglia of the African giant snail, Achatina fulica.

Three novel neuropeptides, isolated from ganglia of the African giant snail, Achatina fulica, were named WWamide-1, -2 and -3. These substances were biologically active heptapeptide amides with a Trp residue at both the N- and C-termini. WWamide-1, which displayed an inhibitory activity on a central neuron of the snail, exhibited peripherally modulatory effects on muscular contractions of not only the gut and other tissues of the snail but also certain tissues of other molluscs.

Amino Acid Sequence↗
PubMed1993

Two novel tachykinin-related neuropeptides in the echiuroid worm, Urechis unicinctus.

Two novel neuropeptides, urechistachykinin I (H-Leu-Arg-Gln-Ser-Gln-Phe-Val-Gly-Ser-Arg-NH2) and urechistachykinin II (H-Ala-Ala-Gly-Met-Gly-Phe-Phe-Gly-Ala-Arg-NH2), were isolated from the ventral nerve cords of the echiuroid worm, Urechis unicinctus. These peptides showed a contractile action on the inner circular body-wall muscle of the animal. Their amino acid sequences were found to be significantly homologous with those of the vertebrate and insect tachykinins. The urechistachykinins potentiated spontaneous rhythmic contractions of the cockroach hindgut.

Amino Acid Sequence↗
PubMed1993

A Mytilus peptide related to the small cardioactive peptides (SCPs): structure determination and pharmacological characterization.

1. An SCP-related peptide, Ala-Pro-Asn-Phe-Leu-Ala-Tyr-Pro-Arg-Leu-NH2, was isolated from the ABRMs of Mytilus edulis. The peptide was designated Mytilus SCP. 2. At 10(-10) M or higher, Mytilus SCP showed a potentiating effect on phasic contraction of the ABRM in response to repetitive electrical stimulation. In contrast, the peptide did not show any potentiating effect on contractures in response to ACh and the FMRFamide-related Mytilus decapeptide, suggesting that the potentiating effect on phasic contraction was brought about by an action of the peptide on the nerve elements in the ABRM. 3. At 10(-8) M or higher, Mytilus SCP showed a catch-relaxing effect in addition to the potentiating effect. The relaxing effect was blocked by mersalyl, suggesting that it was also brought about by a presynaptic action. 4. Various analogues of Mytilus SCP were examined on the ABRM. Leu-Ala-Tyr-Pro-Arg-Leu-NH2 was suggested to be the minimum structure required for both potentiating and relaxing activities on the ABRM. Leu-D-Ala-Tyr-Pro-Arg-D-Leu-NH2 and D-Leu-Ala-Tyr-Pro-Arg-D-Leu-NH2 were found to show strong potentiating and relaxing activities, though they were less potent than the Mytilus SCP.

Amino Acid Sequence↗
PubMed1993

Further identification of bioactive peptides in the anterior byssus retractor muscle of Mytilus: two contractile and three inhibitory peptides.

1. Two contractile and three inhibitory peptides were newly isolated from the anterior byssus retractor muscles (ABRMs) of the bivalve mollusc Mytilus edulis by using the muscle as the bioassay system. 2. The structures of the two contractile peptides were GPFGTHIKamide (GPFG-8) and GPFGLNKHGamide (GPFG-9). The contractile response of the ABRM to the first-time application of GPFG-8 or GPFG-9 was of considerable size. The threshold concentrations of the peptides were around 10(-9) M. However, the contractile response to the second-time application was far smaller than that to the first-time application in both cases. Namely, the muscle showed tachyphylaxis to the peptides. 3. Two of the three inhibitory peptides were members of the Mytilus-inhibitory-peptide (MIP) family. Their structures were RAPLFIamide (MIP6) and RSPMFVamide (MIP7). The peptides, as well as the other MIPs previously identified, showed a potent inhibitory effect on phasic contraction of the ABRM in response to repetitive electrical stimulation. The remaining one was an MIP-related peptide (MIP-RP) having the sequence of MRYFVamide. The MIP-RP was less potent than the two MIPs in inhibiting the contraction of the ABRM.

Amino Acid Sequence↗