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Biomedical subjects

H Aoyagi

Publications and source records attributed to H Aoyagi.

At least 91 records · Page 5Linked to original sources
PubMed1988

Biosynthesis and localization of rat liver microsomal carboxyesterase E1.

One of the microsomal carboxyesterases, carboxyesterase E1, was purified from rat liver to homogeneity. Carboxyesterase E1 is a glycoprotein of high mannose type, and is composed of three identical subunits of 59 kDa each. It is very similar to "esterase pI 6.0" described by Menthein et al. (Arch. Biochem. Biophys. 200, 547-559 (1980)) in molecular weight, amino acid composition, and enzymic activities. Carboxyesterase E1 was found to be evenly distributed between rough and smooth microsomes. The content of the enzyme in microsomes was about 1.5% of total microsomal protein. It was exclusively located on the luminal side of microsomes, and was not detected immunologically in Golgi fractions or serum. In vitro translation of rat liver RNA by reticulocyte lysate showed that carboxyesterase E1 was synthesized preferentially on the bound ribosomes, as a precursor peptide larger than the peptide of the mature enzyme. Carboxyesterase E1 was solubilized from microsomes by treatment with low concentrations of detergents. However, it was not released from microsomes by treatment with a synthetic peptide which made the microsomal membrane permeable to soluble protein molecules. Carboxyesterase E1 is not a soluble luminal protein, and seems to be bound to the luminal surface of the membrane.

Amino Acids↗
PubMed1988

Interaction of basic extension peptide fragments of adrenodoxin precursor with phospholipid vesicles.

Two extension peptide fragments PA1-4 and PA17-32, which correspond to the residues 1-14 and 17-32, respectively, of adrenodoxin precursor, were synthesized by the solution method to find a sequence necessary for the import of the precursor into mitochondria. Biological assay showed that PA1-14 inhibited the import of two mitochondrial enzyme precursors, but PA17-32 showed no inhibition, indicating that the N-terminal sequence has important information for import. CD spectra of the peptides demonstrated that PA1-14 formed alpha-helical structure in Tris-HCl buffer (pH 7.4) containing acidic phospholipid liposomes. Furthermore, PA1-14 induced the moderate leakage of carboxyfluorescein from phospholipid vesicles. The relationship between the structure and function of the peptides is discussed.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1988

[Diagnosis of anterior perineal anus (APA)--significance of electromyographic evaluation of the external anal sphincter location].

APA is a common cause of constipation, and is the mild case of the imperforated anus. On diagnosing APA, anterior displacement of the anus and normal distribution of the external anal sphincter to the anus are essential. To determine the location of the anus in the perineum simple clinical technique was developed. In 61 normal cases, the result of measurement was almost same in each sex, but in 3 APA cases the location were anteriorly dislocated than normal cases. Distribution of the external anal sphincter was evaluated with electromyographic technique, and location map of the sphincter was made. In 3 APA cases, the anus was totally surrounded by the external anal sphincter, but in 17 ano-cutaneous fistula cases, the opening was anteriorly dislocated to the sphincter distribution map. As a conclusion, newly proposed simple clinical technique to determine anal location and electromyographic examination of the external and sphincter distribution are very useful in objective diagnosis of APA.

Anal Canal↗
PubMed1987

Environment-dependent conformation and antimicrobial activity of a gramicidin S analog containing leucine and lysine residues.

An analog of gramicidin S, cyclo(-L-Leu-L-Lys-L-Leu-D-Leu-L-Leu-)2, in which four out of five amino acid components of gramicidin S were substituted, has been synthesized. This analog assumes a conformation similar to that of gramicidin S in acidic liposomes and a random conformation in neutral liposomes. The antimicrobial activity of this analog corresponded to one-fourth of that of gramicidin S. A possible mechanism for conformational changes in acidic liposomes is discussed.

Amino Acid Sequence↗
PubMed1987

Interaction of synthetic fragments of the extension peptide of cytochrome P-450(SCC) precursor with phospholipid bilayer.

Six peptide fragments, SEP6-11, SEP6-15, SEP1-11, SEP1-15, SEP1-20, and SEP25-39, corresponding to the residues 6-11, 6-15, 1-11, 1-15, 1-20, and 25-39, respectively, of the extension peptide of cytochrome P-450(SCC) precursor were chemically synthesized by the solution method. CD spectra of the peptides indicated that SEP1-15 and SEP1-20, which inhibit the import of the precursor, held a random conformation in a Tris-HCl buffer and a partially ordered conformation (like alpha-helix or type II' beta-turn) in a buffer containing acidic liposomes. Slightly changed spectra were observed for SEP1-15 and SEP1-20 in the buffer containing neutral liposomes and in MeOH, respectively. Other peptides which show weak or no inhibitory effect had almost random conformations in these solvents. The hydrophobic moments of SEP1-15 and SEP1-20 when they take alpha-helical conformation are very small, suggesting that amphiphilic helical property is not always necessary for the import of the precursor, although partially ordered conformation seems to be required. The ability of SEP1-15 and SEP1-20 to induce leakage of carboxyfluorescein from the inside of dipalmitoyl-DL-alpha-phosphatidylcholine (DPPC) or DPPC-dipalmitoyl-DL-alpha-phosphatidylglycerol (3:1) vesicles was much greater than that of other peptides. The leakage induction ability of the peptides qualitatively parallels the degree of their inhibition of the import of the precursor. Perturbation of the membranes caused by the action of the peptides in their partially ordered form may be important for the import of the precursor into mitochondria.

Amino Acids↗
PubMed1987

Synthetic partial extension peptides of P-450(SCC) and adrenodoxin precursors: effects on the import of mitochondrial enzyme precursors.

Various portions of the extension peptides of P-450(SCC) precursor were chemically synthesized. The effects of these peptides on the import of enzyme precursors into mitochondria were examined. Peptides SEP1-15 and SEP1-20, corresponding to the amino terminal portion of the extension peptides, strongly inhibited the import of P-450(SCC) precursor into mitochondria. These peptides were effective at concentrations above 30 microM, and complete inhibition was observed at 100 microM. SEP1-11, which is shorter than SEP1-15 and SEP1-20, showed very weak inhibition. SEP25-39, which corresponds to the carboxy terminal portion of the extension peptide, did not affect the import of the precursor. The import of P-450(11 beta) and adrenodoxin precursors were also inhibited by SEP1-15. Another peptide, AEP1-14, which corresponds to the amino terminal portion of the extension peptide of adrenodoxin precursor, was also synthesized. The peptide inhibited the import of both adrenodoxin and P-450(SCC) precursors into mitochondria. The import of malate dehydrogenase was also inhibited by SEP1-15 and AEP1-14. The rate of the internalization of the precursor into mitochondria was decreased by the peptides. The amount of the precursor bound to the surface of mitochondria and the processing of adrenodoxin precursor were not affected. The respiratory activities of isolated mitochondria were not influenced by SEP1-15 even at 100 microM. We conclude that the inhibitory activities of the synthetic partial extension peptides on the import of enzyme precursors into mitochondria require the presence of about fifteen amino acid residues in the amino terminal portion of the extension peptides, and the inhibition of the import by the peptides was dependent on the blockage of the internalization of the precursors into mitochondria.

Adrenodoxin↗
PubMed1987

Synthesis, receptor binding activity and fluorescence property of fluorescent enkephalin analogs containing L-1-pyrenylalanine.

The novel fluorescent amino acid, L-1-pyrenylalanine (L-Pya), was prepared by the asymmetric hydrogenation of cyclic dehydrodipeptide. Fluorescent enkephalins containing one or two Pya residues at position 1,4 or 5 of [D-Ala2, Leu5]enkephalin were synthesized by the solution method. Mono-Pya-enkephalins showed strong fluorescence intensities and potent binding affinities with specificity and selectivity for opiate receptors. However, di-Pya-enkephalins showed markedly decreased receptor binding affinities. These results indicate that the incorporation of two Pya residues into enkephalin makes the peptide unable to interact with the opiate receptors, although introduction of one Pya residue is effective to elicit a specific receptor interaction. Di-Pya-enkephalins showed intramolecular excimer spectra, indicating that the peptides are able to take possible folded conformations.

Animals↗
PubMed1986

Relationship between antimicrobial activity and amphiphilic property of basic model peptides.

Several cationic model peptides of the prepiece moieties of mitochondrial protein precursors were found to be active against Gram-positive bacteria, but inactive against Gram-negative bacteria. The CD spectra of the model peptides in the presence of phospholipid liposomes demonstrated that antimicrobial activity was generally in parallel with the content of the alpha-helical amphiphilicity. The results indicate that appropriate positioning of cationic and hydrophobic groups in the stable alpha-helical structure of the peptides is important to exhibit antimicrobial activity. These peptides also have an ability to leak carboxyfluorescein from acidic and neutral phospholipid vesicles, suggesting that the peptides interact with the bacterial membrane to perturb it.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1986

Tyr1-substituted and fluorescent Pya1-enkephalins bind strongly and selectively to mu and delta opiate receptors.

The fluorescent enkephalins in which an essential Tyr1 residue is replaced by L-1-pyrenylalanine (Pya) were synthesized and examined in the receptor binding assays. [Pya1, Leu5]Enkephalin and its methyl ester showed binding characteristics specific for the opiate receptors, exhibiting a potent inhibition of Tyr1-containing enkephalins. Surprisingly, the methyl ester displayed almost the same potencies to those of DAGO-enkephalin. This analog bound 24-fold more strongly to mu than to delta-receptors. C-terminal free analog Pya1-Enk-OH was delta-preferential with a fairly good affinity. These results indicate that Tyr1 in enkephalin is not necessary to recognition of the opiate receptors.

Alanine↗
PubMed1985

Delta and mu opiate receptor probes: fluorescent enkephalins with high receptor affinity and specificity.

The fluorescent amino acid, L-1-pyrenylalanine (Pya) was incorporated into [D-Ala2,Leu5]enkephalin and its methyl ester at position 4 or 5. Pya-enkephalins showed strong fluorescent intensity and displayed high binding affinity for opiate receptors. Pya4-enkephalins showed high specificity for the mu receptors, while Pya5-enkephalins showed high specificity and selectivity for the delta receptors. Particularly, [D-Ala2,Pya5]enkephalin was as potent as the most utilized delta-specific ligand of [D-Ala2,D-Leu5]enkephalin (DADLE), and yet its delta-selectivity was about 5-times greater than that of DADLE. Thus, Pya-enkephalins per se can be utilized as a fluorescent probe or tracer for the opiate receptor-binding assays.

Alanine↗
PubMed1985

Effects of synthetic model peptides resembling the extension peptides of mitochondrial enzyme precursors on import of the precursors into mitochondria.

One common and characteristic feature of the extension peptides of mitochondrial enzyme precursors is the presence of repeating short stretches of uncharged amino acids linked by basic amino acids. We synthesized several model peptides having this particular feature of the extension peptides. The peptides contained arginine or lysine as a basic amino acid residue linking sequences of two to four residues of leucine and alanine. We examined the effects of the peptides on the import of the precursors of two mitochondrial enzymes, cytochrome P-450(SCC) and adrenodoxin, and found that the peptides were generally inhibitory to the import of the precursors into mitochondria. The effective concentrations of some of the inhibitory peptides were as low as a few microM. The peptides containing lysine instead of arginine had an essentially similar inhibitory effect on the import. The peptides did not inhibit the binding of pre-P450(SCC) to the surface of mitochondria. The synthetic model peptides uncoupled oxidative phosphorylation of mitochondria prepared from either rat liver or bovine adrenal cortex, and induced leakage of enzymes from the inner compartments of mitochondria. However, the synthetic model peptides did not solubilize membrane-bound enzymes from mitochondria, suggesting that their effect on the membranes is different from that of detergents. The synthetic model peptides seem to bind to the membranes causing significant perturbation in the membrane structure, which is possibly related to the functions of the particular common sequence found in the extension peptides of mitochondrial enzyme precursors.

Adrenodoxin↗
PubMed1985

[Bowel function of spina bifida].

Bowel function of the spina bifida was studied by clinical assessment and anorectal manometric studies. Anorectal pressure profiles were well correlated with clinical assessment but not with recto-anal inhibitory reflexes. Early training of the defecation is emphasized to obtain good bowel function.

Defecation↗
PubMed1985

Synthesis of analogs of K-582A, an antibiotic heptapeptide.

K-582 A, an antibiotic heptapeptide, has a sequence of H-L-Arg-L-Arg(OH)-D-Orn-L-Thr-D-Orn-L-Lys-D-Tyr-OH (Arg(OH), threo-gamma-hydroxyarginine). In order to investigate the relationship between structure and antimicrobial activity, four shortened analogs, des-L-Arg1, L-Arg(OH)2-K582 A (pentapeptide), des-L-Arg(OH)2-K-582 A (hexapeptide) and their N-acetyl derivatives, were synthesized by the conventional method. None of them, however, showed any antimicrobial activity. Three more analogs, [L-Lys2]K-582 A, [L-Orn2]K-582 A and [L-Arg2]K-582 A, were synthesized. Among them, only [L-Arg2]K-582 A showed substantial activity against Candida krusei and Saccharomyces rouxii, indicating that the presence of a guanidyl side chain at position 2 is an essential factor for the induction of activity.

Amino Acid Sequence↗
PubMed1984

Cyclic peptides. XVI. Syntheses of AM-toxin I analogs containing a lower or higher homolog of the component L-2-amino-5-(p-methoxyphenyl)pentanoic acid residue.

In order to investigate the influence of the side-chain length at position 3 of AM-toxin I (cyclic tetradepsipeptide) on necrotic activity for apple leaf, two analogs of AM-toxin I, [L-2-amino-4-(p-methoxyphenyl)butanoic acid]-AM-toxin I and [L-2-amino-6-(p-methoxyphenyl)hexanoic acid]-AM-toxin I, were synthesized by the conventional method. Spectra of 1H-n.m.r., u.v. and CD of the analogs were similar to those of natural or synthetic AM-toxin I. The toxic activities of the analogs for apple leaf, however, were weak, indicating that the exact side-chain length at position 3 must be one of the important factors for the induction of the activity. The interaction between AM-toxin I and a possible receptor on apple leaf is discussed.

Circular Dichroism↗
PubMed1983

[4,4'-D-diaminopropionic acid]gramicidin S: a synthetic gramicidin S analog with antimicrobial activity against Gram-negative bacteria.

Gramicidin S is especially active against Gram-positive bacteria; e.g., Staphylococcus aureus. An analog, [4,4'-D-diaminopropionic acid]gramicidin S, which contains D-diaminopropionic acid residues instead of D-phenylalanine residues, has been synthesized. This analog is active against some of the Gram-negative bacteria; e.g., Escherichia coli and Salmonella typhosa. Activities of several related analogs are discussed.

Bacteria↗
PubMed1983

Studies of peptide antibiotics. XLIII. Syntheses of gramicidin S analogs containing D-serine or dehydroalanine in place of D-phenylalanine and asymmetric hydrogenation of the dehydroalanine residue.

Gramicidin S (GS) analogs, [D-Ser4,4']-GS and its precursor [O-benzyl-D-Ser4,4']-GS, were synthesized by the conventional method in order to evaluate the role of the hydroxymethyl side chains in D-Ser at 4,4' positions on the biological activity. Another analog [L-Orn(delta-Boc)2,2',delta Ala4,D-Ser4']-GS was prepared from [D-Ser4,4']-GS by t-butyloxycarbonylation and successive dehydration using dicyclohexylcarbodiimide-CuCl as dehydrating reagent. The delta Ala residue was asymmetrically hydrogenated to D-Ala in the presence of Pd-black. On the microbial assays, [O-benzyl-D-Ser4,4']-GS showed high antimicrobial activity as natural GS, but [D-Ser4,4']-GS showed low activity; the structure-activity relationships of the analogs were discussed.

Alanine↗
PubMed1983

[Influence of the catheter diameter on the manometric measurements of the lower esophageal sphincter (LES); with special reference to the application for children].

In order to study the influence of the catheter diameter for measurement of the LES pressure, the LES pressure of rats was measured by using 6 kinds of catheters of different diameters. The results showed that the pressure of LES was 13.8 +/- 3.7 cmH2O, 15.2 +/- 3.2 cmH2O, 18.1 +/- 4.4 cmH2O, 22.3 +/- 6.7 cmH2O, 30.3 +/- 10.0 cmH2O and 42.0 +/- 11.9 cmH2O, respectively with the catheter diameter of 3, 4, 5, 6, 8 and 10 Fr. The larger the diameter of the esophageal tube, the higher the pressure of LES, in the range of more than a 5 Fr. tube. (P less than 0.05) Even in the LES model made of the isolated esophagus of rat, the diameter-pressure curve was similar with the LES measurement of the anesthetized rats. The increased pressure of LES was caused by an increase in tension from the esophageal wall to its proper pressure. For measurement of LES pressure of rats, the catheter of 3 Fr. or 4 Fr. in the outer diameter was more suitable since there was no tension from the esophageal wall. In order to search an appropriate catheter diameter for children, the LES pressure of 11 neonates and 12 infants were either measured with various kinds of tubes. The pressure of LES of neonates was 34.4 +/- 8.4 cmH2O, 36.4 +/- 10.7 cmH2O, 39.6 +/- 10 cmH2O, 46.0 +/- 8.7 cmH2O and 61.8 +/- 22.9 cmH2O, respectively with the catheter diameter of 4, 6, 8, 10 and 12 Fr.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗