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K Samejima

Publications and source records attributed to K Samejima.

At least 55 records · Page 3Linked to original sources
PubMed1993

Tertiary and quaternary branched polyamines distributed in thermophilic Saccharococcus and Bacillus.

The distribution of long linear, tertiary and quaternary branched polyamines in twenty thermophilic Gram-positive strains belonging to the genera Saccharococcus, Bacillus or Amphibacillus were analysed by high-performance liquid chromatography and gas chromatography. The extremely thermophilic S. thermophilus contained a tertiary tetra-amine, N4-aminopropylspermidine, a linear penta-amine, thermopentamine, a tertiary penta-amine, N4-aminopropylspermine, and a quaternary penta-amine, N4-bis(amino-propyl)spermidine. N4-aminopropylspermine [NH2(CH2)3N((CH2)3NH2)(CH2)4NH(CH2)3NH2] first found in this study, was also detected in the extremely thermophilic 'B. caldolyticus' and 'B. caldotenax' and the moderately thermophilic B. stearothermophilus, B. smithii and B. thermocatenulatus.

Bacillus↗
PubMed1992

Interactions between natural polyamines and tRNA: an 15N NMR analysis.

15N NMR spectroscopy was used to explore the interactions between natural polyamines and Escherichia coli tRNA. It was found that when tRNA is added to solutions of 15N-labeled spermine or spermidine, there is a considerable decrease in the relative heights of the -NH(2+)--resonances with respect to the signals arising from the -NH3+ groups. The presence of tRNA was also found to reduce the longitudinal relaxation times T1 of the nitrogens, mainly those of the -NH(2+)- groups. The longitudinal relaxation times of the nitrogens were used to characterize the temperature dependence of the binding, and they allowed us to calculate the activation energies that determine the correlation times of amino groups in the presence of tRNA. Both the thermodynamic and the relaxation results indicate that (i) spermine binds more strongly to tRNA than spermidine does and (ii) within each of these molecules the -NH(2+)- groups bind more strongly to tRNA than the more electropositive -NH3+ moieties. This specificity suggests that the interaction between polyamines and tRNA cannot be described exclusively in terms of electrostatic forces and that other interactions (most likely, hydrogen bonding) are very important for establishing the polyamine-tRNA link. Some of the factors that may conspire against the binding of -NH3+ groups to tRNA are briefly discussed.

Escherichia coli↗
PubMed1992

Novel linear and branched polyamines in the extremely thermophilic eubacteria Thermoleophilum, Bacillus and Hydrogenobacter.

Novel tertiary branched tetra-amines, quaternary branched penta-amines, linear penta-amines and linear hexa-amines were distributed as the major polyamines in six obligately extremely thermophilic eubacteria belonging to Thermoleophilum, Bacillus or Hydrogenobacter. The major polyamine of Thermoleophilum album and Thermoleophilum minutum was identified as a quaternary branched penta-amine, 4,4-bis(3-aminopropyl)-1,8-diamino-4-azaoctane (NH2[CH2]3N+([CH2]3NH2)2[CH2]4NH2) by h.p.l.c., t.l.c. and g.c.-m.s. Hydrogenobacter thermophilus and Hydrogenobacter halophilus contained another quaternary branched penta-amine, 4,4-bis(3-aminopropyl)-1,7-diamino-4-azaheptane (NH2[CH2]3N([CH2]3NH2)2[CH2]3NH2) as the major polyamine, and tertiary branched tetra-amines (4-(3-aminopropyl)-1,7-diamino-4-azaheptane (NH2[CH2]3N([CH2]3NH2)[CH2]3NH2), 4-(3-aminopropyl)-1,8-diamino-4-azaoctane (NH2[CH2]3N([CH2]3NH2)[CH2]4NH2)) and 4,4-bis(3-aminopropyl)-1,8-diamino-4-azaoctane were confirmed as minor components. Bacillus schlegelii contained a branched tetra-amine, 4-(3-aminopropyl)-1,8-diamino-4-azaoctane, a branched penta-amine, 4,4-bis(3-aminopropyl)-1,8-diamino-4-azaoctane, a linear penta-amine, 1,16-diamino-4,8,13-triazahexadecane (NH2[CH2]3NH[CH2]3NH[CH2]4NH[CH2]3NH2) and linear hexa-amine(s), 1,20-diamino-4,8,12,17-tetra-azaeicosane (NH2[CH2]3NH[CH2]3NH[CH2]3NH[CH2]4NH[CH2]3NH2 ) and/or 1,20-diamino-4,8,13,17-tetra-azaeicosane (NH2[CH2]3NH[CH2]3NH[CH2]4NH[CH2]3NH[CH2]3NH2 ).

Bacillus↗
PubMed1991

Putrescine or spermidine binding site of aminopropyltransferases and competitive inhibitors.

A model of the active site of aminopropyltransferases was proposed based on the study of a number of monoamino and diamino compounds as potential inhibitors and substrates, respectively, of spermidine synthase purified from pig liver. The active site seems to have a relatively large hydrophobic cavity adjacent to a negatively charged site, to which a protonated amino group of putrescine binds, with another amino group of putrescine being situated in the hydrophobic cavity as a free form to be aminopropylated by decarboxylated S-adenosylmethionine. On the basis of the above-mentioned model, another modified one was proposed for spermine synthase, and several compounds mentioned model, another modified one was proposed for spermine synthase, and several compounds designed according to the modified model were found to potently inhibit spermine synthase, purified from rat brain, in competition with spermidine. The newly developed inhibitors were about two orders of magnitude more potent in vitro than a known inhibitor of spermine synthase, dimethyl(5'-adenosyl)sulfonium perchlorate.

Animals↗
PubMed1991

Polyamine-linked sepharoses: preparation and application to mammalian spermine synthase.

Seven different polyamine-linked Sepharose derivatives were prepared for the affinity chromatography of spermidine and spermine binding macromolecules: Spermine synthase from rat and hog brain was used as a model protein with a spermidine binding site. Comparative studies of the affinities of the enzymes for the seven matrixes suggested that two negative charges, three to four methylene groups apart, should be present at the decarboxylated S-adenosylmethionine binding site and should improve the binding of the enzyme to the Sepharose derivative. Two negative charges at the spermidine binding site would be expected to do the same. Three affinity matrixes linked with 1,17-diamino-4,9,14-triazaheptadecane, 1,21-diamino-4,9,13,18-tetraazaheneicosane, and 5-spermine carboxylic acid, respectively, had an affinity for spermine synthases higher than that of spermine-Sepharose, which has been used for the purification of spermine synthase. The first of these matrixes was used and proved to be effective for the purification.

Animals↗
PubMed1991

Polyamine distributions in thermophilic eubacteria belonging to Thermus and Acidothermus.

Triamines such as norspermidine, spermidine, and homospermidine and tetraamines such as norspermine, spermine, thermospermine, and aminopropylhomospermidine were found to be distributed ubiquitously in the eight extremely thermophilic (growing at 70 degrees C) Thermus species tested. Three linear pentaamine (caldopentamine, homocaldopentamine, and thermopentamine), two linear hexaamines (caldohexamine and homocaldohexamine), two tertiary branched tetraamines (N4-aminopropylnorspermidine and N4-aminopropyl-spermidine), and quaternary branched pentaamines such as N4-bis(aminopropyl)norspermidine and N4-bis(aminopropyl)spermidine were detected in T. thermophilus HB8, T. filiformis Wai33 A1, T. flavus AT-62, and T. caldophilus GK24. The linear hexaamines and branched polyamines were absent in T. aquaticus YT-1, T. sp. X-1, T. sp. T2, and T. sp. T351, in which linear pentaamines were minor components. Moderately thermophilic Thermus ruber and Thermus sp. K-2 contained putrescine, spermidine, norspermidine, homospermidine, spermine, norspermine, thermospermine, and aminopropylhomospermidine. No pentaamines, hexaamines, or branched polyamines were found in these two moderately thermophilic Thermus species. On the other hand, moderately thermophilic, acidophilic Acidothermus cellulolyticus was devoid of all the polyamines.

Chromatography, High Pressure Liquid↗
PubMed1989

Correlation between the effects of polyamine analogues on DNA conformation and cell growth.

Effects of a number of synthetic analogues of the natural polyamines on the B-Z transition of poly(dG-me5dC) and on the aggregation of calf thymus DNA in solution were studied using circular dichroic and UV spectroscopy. The efficiency of induction of the B-Z transition decreased with a decrease in the length of the central alkyl chain of the analogues, and the ability of analogues to aggregate DNA was markedly reduced for compounds ethylated at the terminal amines. Both structural variations appear to have important effects on the biological functions of polyamines. Most analogues studied depleted intracellular levels of natural polyamines, but only those that did not readily induce the B-Z transition and/or aggregate DNA were good inhibitors of cell growth. All but one of the analogues studied were able to rescue cells--at least in part--from the growth-inhibitory effects of alpha-difluoromethylornithine. The single analogue that was unable to effect rescue also failed to induce both the B-Z transition and the aggregation of DNA.

Animals↗
PubMed1988

Effect of various polyamine analogs on in vitro polypeptide synthesis.

Various polyamine analogs were examined for their ability to stimulate and to function as sparing agents for the Mg2+ requirement in polypeptide synthesis at various temperatures in Escherichia coli (37 and 47 degrees C) and the extremely thermophilic Thermus thermophilus (60 and 70 degrees C) cell-free systems. The optimal concentration of each polyamine analog increased as the incubation temperature was elevated. At a fixed temperature, the optimal concentration of polyamine analogs was in the order diamines greater than triamines greater than tetraamines greater than pentaamines. All diamines tested stimulated polypeptide synthesis almost equally but lowered the optimal Mg2+ concentration in the order diaminopropane greater than putrescine greater than cadaverine. The degree of diamine stimulation was maximal at 37 degrees C. The effects of three triamines were very similar in the E. coli system but in the T. thermophilus system spermidine was most effective in stimulation of polypeptide synthesis. From the results of experiments using tetraamines and pentaamines, it was deduced that the presence of both aminobutyl and aminopropyl groups in polyamine analogs is important for stimulation of polypeptide synthesis. In the E. coli system, triamines were the most effective polyamines for stimulation of polyphenylalanine synthesis at both 37 and 47 degrees C, while, in the T. thermophilus system, thermospermine, a tetraamine, was most effective at 60 degrees C and 3,4,4,3-pentaamine was most effective at 70 degrees C.

Cell-Free System↗
PubMed1988

Monospecific antiserum to rat spermidine synthase and its application to rat tissues and several mammals.

Monospecific antiserum to rat spermidine synthase was prepared by immunization of rabbits with purified enzyme protein from rat prostate, and its usefulness for analysis of spermidine synthase protein in not only rat tissues but also several other mammals was demonstrated by Western blotting and immunotitration of the enzyme activity. Application of the antiserum for elucidating the relationship between the enzyme activity and protein in normal rat tissues strongly suggested that marked difference in spermidine synthase activity among rat tissues depends solely on the difference in the amount of enzyme protein. Also, application of the antiserum for analyzing spermidine synthase from liver of mouse, rat, guinea pig, pig, and human, showed that the enzymes had a similar subunit molecular weight of 35,000 and a cross-reactivity with the antiserum, exhibiting almost the same immunoreactivity to mouse enzyme as to rat enzyme. Thus, it was suggested that the antiserum would be useful for further studies of mammalian spermidine synthase from the viewpoints of enzymology and molecular biology.

Animals↗
PubMed1987

Occurrence of aminopropylhomospermidine and canavalmine in the hamster epididymis.

The Syrian hamster epididymis contains rather high levels of sym-homospermidine, N1-acetylspermidine and N1-acetylspermine in addition to the common polyamines putrescine, spermidine, and spermine. In the present study two other polyamines were identified in adult hamster epididymis by gas chromatography; they are aminopropylhomospermidine [NH2(CH2)3NH(CH2)4NH(CH2)4NH2] and canavalmine [NH2(CH2)4NH(CH2)3NH(CH2)4NH2]. The molar ratio of the former to the latter was about 2:1. This is the first report to show that tetraamines other than spermine are present in mammalian tissues.

Animals↗
PubMed1985

Determination of various 15N-enriched spermidines with gas chromatography-mass spectrometry.

A novel method for the determination of all eight kinds of variously 15N-enriched spermidines including the natural one is described using gas chromatography-mass spectrometry. After strict assignments of nitrogen(s) in fragment ions split from pentafluoropropionyl derivative of spermidine with 20 eV impact, six fragments (P7 and P10 containing N1 and N4 of spermidine, P8 and P11 containing N4 and N8, and P14 and P15 containing N1, N4, and N8 as designated in the text) were found to be useful for calculating relative contents of the various spermidines. The calculation was carried out by a computer program with the input of 20 relative intensities observed at m/z 259-261, 273-275, 379-381, 393-395, 436-439, and 464-467. Reliability of the method was examined by measuring known mixtures of authentic spermidines. In an experiment testing reproducibility, an average coefficient of variation was 4.8% with a reasonable accuracy for the eight spermidines. Linearity of relative ratios of 15N-enriched spermidines to the natural one was assured with an average correlation coefficient of 0.996. The present method was applied for spermidine synthase reaction, and it was confirmed that the enzyme from rat prostate could not discriminate against 15N of putrescine.

Animals↗
PubMed1985

Functionality of muscle proteins in gelation mechanisms of structured meat products.

Recent advances in muscle biology concerning the discoveries of a large variety of proteins have been described in this review. The existence of polymorphism in several muscle proteins is now well established. Various isoforms of myosin not only account for the difference in physiological functions and biochemical activity of different fiber types or muscles, but also seem to differ in functional properties in food systems. The functionality of various muscle proteins, especially myosin and actin in the gelation process in modal systems which simulate structured meat products, is discussed at length. Besides, the role of different subunits and subfragments of myosin molecule in the gelation mechanism, and the various factors affecting heat-induced gelation of actomyosin in modal systems are also highlighted. Finally, the areas which need further investigation in this discipline have been suggested.

Actinin↗
PubMed1984

Polyamine synthesis in mammalian tissues. Isolation and characterization of spermidine synthase from bovine brain.

Spermidine synthase (EC 2.5.1.16) was purified to apparent homogeneity (about 11 000-fold) from bovine brain by affinity chromatography, with S-adenosyl-(5')-3-thiopropylamine linked to Sepharose as the adsorbent. The enzyme preparation was free from S-adenosylmethionine decarboxylase (EC 4.1.1.50) and spermine synthase (EC 2.5.1.22) activities. The native enzyme had an apparent Mr of 70 000, was composed of two subunits of equal size, and had an isoelectric point at pH 5.22. The apparent Km values for putrescine and decarboxylated adenosylmethionine [S-adenosyl-(5')-3-methylthiopropylamine] were 40 microM and 0.3 microM respectively. Cadaverine and 1,6-diaminohexane could replace putrescine as the aminopropyl acceptor, although the reaction rates were only 6% and 1% respectively of that obtained with putrescine. Ethyl, propyl and carboxymethyl analogues of decarboxy-S-adenosylmethionine could act as propylamine donors. Both the reaction products, spermidine and 5'-methylthioadenosine, were mixed-type inhibitors of the enzyme. On the basis of initial-velocity and product-inhibition studies, a ping-pong reaction mechanism for the spermidine synthase reaction was ruled out.

Adenosine↗
PubMed1984

Differences between homogeneous spermidine synthases isolated from rat and pig liver.

Spermidine synthase was purified to homogeneity from rat and pig liver by a method modified from a previously reported one using DEAE-Sepharose, S-adenosyl(5')-3-thiopropylamine-Sepharose affinity chromatography, Sephacryl S-300 gel filtration and polyacrylamide gel electrophoresis. No apparent difference between the two enzymes was observed in specific activity, molecular weight (74,000), or subunit composition (two subunits). However, significant differences were observed in their pI values, which were 5.16 for the pig enzyme and 5.34 for the rat enzyme, and their peptide maps. Amino acid compositions of the two enzymes were closely related, but differed significantly in some amino acids. In addition, the rat enzyme was more sensitive to inhibition by S-adenosyl-1,8-diamino-3-thiooctane than the pig enzyme.

Amino Acids↗