巻号一覧
109 巻, 5 号
選択された号の論文の23件中1～23を表示しています
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Yoshio Yamakawa, Tamotsu Omori-Satoh, Jun-ichi Maeyama1991 年 109 巻 5 号 p. 667-669
発行日: 1991年
公開日: 2008/11/18
ジャーナル フリーThe amino acid sequence of a cytotoxic factor, CTF-I, isolated from the venom of the Japanese habu snake (Trimeresurus flavoviridis) has been determined through automatic phenylisothiocyanate degradation of the PE-protein and derived proteolytic peptides. CTF-I consists of 72 amino acids and contains an Arg-Gly-Asp sequence present in trigramin-like peptides isolated from other snake venoms. The primary structure of another cytotoxic factor, CTF-II, consisting of 75 amino acids, was deduced to comprise that of CTF-1 with an additional Glu-Leu-Leu-sequence at its N-terminal.抄録全体を表示PDF形式でダウンロード (298K) -
Yutaka Sakai, Hitoshi Okamoto, Kaname Mogami, Hiroki Matsuo, Yoshiki H ...1991 年 109 巻 5 号 p. 670-673
発行日: 1991年
公開日: 2008/11/18
ジャーナル フリーArtificially mutagenized Drosophila Act88F actin genes with triple and double mutations were expressed in the indirect flight muscles of transgenic flies. The triple mutant actin, GD245T (Gly-36→Glu, Glu-83→Asp, and Gly-245→Asp), induced heat shock protein (hsp) synthesis without affecting flight ability. On the other hand, the double mutation, GD245D (Gly-36→Glu and Glu-83→Asp), disrupted myofibrils but induced little hsp synthesis. These results demonstrate that myofibril degeneration is not the primary cause of the anomalous heat shock gene activation by mutant actins.抄録全体を表示PDF形式でダウンロード (2643K) -
Akio Kanai, Takashi Kuzuhara, Kazuhisa Sekimizu, Shunji Natori1991 年 109 巻 5 号 p. 674-677
発行日: 1991年
公開日: 2008/11/18
ジャーナル フリーTwo new cDNA clones for S-II-related proteins were isolated from a mouse liver cDNA library. Analyses of these clones suggested that S-II proteins are a family of proteins with relatively conserved C-terminal regions but variable N-terminal regions, and that some members of this family are expressed in a tissue-specific manner.抄録全体を表示PDF形式でダウンロード (1430K) -
Xuemin Xu, Noriyuki Koyama, Meizhen Cui, Akihiko Yamagishi, Yoshiaki N ...1991 年 109 巻 5 号 p. 678-683
発行日: 1991年
公開日: 2008/11/18
ジャーナル フリーThe gene encoding NADH dehydrogenase from an alkalophile, Bacillus sp., was cloned and sequenced. The cloned DNA fragment contained an open reading frame of 1, 557 nucleotides which encodes a polypeptide composed of 519 amino acid residues (Mr 55, 830). The predicted amino acid sequence was consistent with the partial amino acid sequences including the N-terminal and C-terminal sequences determined in a previous study. Sequence comparison with other flavoenzymes revealed high homology between the present dehydrogenase and Escherichia coli thioredoxin reductase.抄録全体を表示PDF形式でダウンロード (561K) -
Sumihisa Imakado, Satoshi Koike, Shigeru Kondo, Masaharu Sakai, Masami ...1991 年 109 巻 5 号 p. 684-689
発行日: 1991年
公開日: 2008/11/18
ジャーナル フリーIn order to determine the transactivation domain(s) of the rat estrogen receptor (rat ER), we made a number of rat ER deletion mutants and transfected the mutant plasmids into COS7 cells together with an estrogen-responsive reporter plasmid, ERE-tk(197)-CAT, which contained the estrogen response element of Xenopus vitellogenin A2 gene. We have identified and localized the N-terminal transactivation domain of the rat ER to a hydrophobic region extending from Ala 59 to Glu 140.抄録全体を表示PDF形式でダウンロード (1595K) -
Tadashi Ueda, Yoshimasa Isakari, Hidenori Aoki, Takanori Yasukochi, Sh ...1991 年 109 巻 5 号 p. 690-698
発行日: 1991年
公開日: 2008/11/18
ジャーナル フリーWe prepared the lysozyme derivative in which the β-carboxyl group of Asp101 was modified with α- O-methyl N-glycylglucosaminide as an amide by means of the carbodi-imide reaction (α-MGG lysozyme). Since Asp101 residue is located at the edge of the active site cleft, a 1H-NMR study was carried out for this derivative in order to investigate the interaction between the introduced substituent and the active site cleft. It was confirmed that the α-MGG moiety sat in the active site cleft in α-MGG lysozyme from the reduction of line broadening of the NH-proton of Trp63 located in the active site cleft, the remarkable chemical shift change of the methyl group of the α-MGG moiety upon adding a trimer of N-acetyl-D-glucosamine [(NAG)3], and the NOE between the C6-proton resonance of Trp63 and the methyl resonance of the α-MGG moiety. Furthermore, α-MGG lysozyme had increased thermal stability compared with native lysozyme. Therefore, it was concluded that the α-MGG moiety covalently attached to Asp101 interacted with the active site cleft to increase the thermal stability of lysozyme.抄録全体を表示PDF形式でダウンロード (835K) -
Hideyuki Hayashi, Seiki Kuramitsu, Hiroyuki Kagamiyama1991 年 109 巻 5 号 p. 699-704
発行日: 1991年
公開日: 2008/11/18
ジャーナル フリーThree mutant Escherichip coli aspartate aminotransferases in which Va139 was changed to Ala, Leu, and Phe by site-directed mutagenesis were prepared and characterized. Among the three mutant and the wild-type enzymes, the Leu39 enzyme had the lowest Km values for dicarboxylic substrates. The Km values of the A1a39 enzyme for dicarboxylates were essentially the same as those of the wild-type (Va139) enzyme. These two mutant enzymes showed essentially the same kcat values for dicarboxylic substrates as did the wild-type enzyme. On the other hand, incorporation of a bulky side-chain at position 39 (Phe39 enzyme) decreased both the affinity (1/Km) and catalytic ability (kcat) toward dicarboxylic substrates. These results show that the position 39 residue is involved in the modulation of both the binding of dicarboxylic substrates to enzyme and the catalytic ability of the enzyme. Although the replacement of Va139 with other residues altered both the kcat and Km values toward various substrates including dicarboxylic and aromatic amino acids and the corresponding oxo acids, it did not alter the ratio of the kcat/Km value of the enzyme toward a dicarboxylic substrate to that for an aromatic substrate. The affinity for aromatic substrates was not affected by changing the residue at position 39. These data indicate that, although the side chain bulkiness of the residue at position 39 correlates well with the activity toward aromatic substrates in the sequence alignment of several aminotransfer-ases [Seville, M., Vincent M. G., & Hahn, K. (1988) Biochemistry 27, 8344-8349], the residue does not seem to be involved in the recognition of aromatic substrates.抄録全体を表示PDF形式でダウンロード (612K) -
Yasuzo Nishina, Kyosuke Sato, Kiyoshi Shiga1991 年 109 巻 5 号 p. 705-710
発行日: 1991年
公開日: 2008/11/18
ジャーナル フリーThe 1, 646cm-1 band in a resonance Raman spectrum obtained with excitation in the charge-transfer band of the complex of oxidized D-amino acid oxidase (DAO) with the oxidation product of D-lysine catalyzed by DAO shifted to 1, 617cm-1 upon 2-13C substitu-tion of lysine. Thus, the band is assigned to a C(2)=C(3) stretching mode of the enamine, Δ2-piperideine-2-carboxylate (En). In the enzyme-free solution, the product is preferentially in the cyclic imine form, Δ1-piperideine-2-carboxylate (Im). Thus, DAO has a higher affinity for the enamine form than for the imine form. The pH effects on the affinity of DAO for the product and on the molar absorption coefficient at 630 nm in the charge-transfer band, suggest that the enzyme-bound product is En in the neutral form at the N atom. As the value of observed rate constant between DAO and the product was constant at high product concentrations, the binding mechanism can be explained as follows; E+Im_??_EIM_??_EEn: rapid bimolecular and slow unimolecular processes. The isomerization of the imine form to the enamine form proceeds in the slow process. The low affinity of Im for DAO may be due to a steric repulsion of the hydrogen atoms of Im at C(3) in the active site. The hydrogen atoms of a substrate D-amino acid at C(3), which correspond to the C(3) hydrogens of Im, may act repulsively in the active site and the repulsive energy may induce strain or distortion of the substrate and the enzyme, accelerating the catalytic reaction.抄録全体を表示PDF形式でダウンロード (597K) -
Toshio Yasumori, Yasushi Yamazoe, Ryuichi Kato1991 年 109 巻 5 号 p. 711-717
発行日: 1991年
公開日: 2008/11/18
ジャーナル フリーThe cDNA of a P-450 human-2 and the two other closely related cDNAs, MP-8 (two deduced amino acids substituted) and λPA6 (two deduced amino acids deleted) were expressed in Saccharomyces cerevisiae cells, and their catalytic and chemical properties were compared to identify which cDNA encodes a major S-mephenytoin 4'-hydroxylase in human livers. In immunoblots, P-450 human-2 cDNA-derived protein in yeasts was stained at the position identical with P-450 human-2 purified from liver and a major protein in microsomes of 19 Japanese livers. MP-8- and λPA6-derived proteins were immunostained at positions near, but distinct from P-450 human-2, and were not detected in those 19 livers. All three proteins expressed in yeasts catalyzed hydroxylation of mephenytoin, hexobarbital, benzo [a] pyrene and tolbutamide, although the rates of the hydroxylation of most of the drugs by P-450 human-2 were higher than those of the two others. In addition, these expressed proteins showed clear differences in the hydroxylation of chiral substrates: P-450 human-2 catalyzed the hydroxylation of S-mephenytoin five times faster than that of the R-enantiomer. Similar high enantioselectivities were also observed on the hydroxylation of R- and S-hexobarbital. However, MP-8- and λhPA6-derived proteins catalyzed hydroxylation of these two drugs with less or almost no stereoselectivity. These results indicate that only a few amino acid alterations cause dramatic changes in both the chemical and catalytic properties of P-450 human-2.抄録全体を表示PDF形式でダウンロード (3131K) -
Kazuo Umetsu, Katsuko Yamashita, Tsuneo Suzuki1991 年 109 巻 5 号 p. 718-721
発行日: 1991年
公開日: 2008/11/18
ジャーナル フリーA blood type B binding lectin (CJA-B) was isolated from the hemolymph of the crab Charybdis japonica by affinity chromatography on Sephadex G-200. The molecular mass of the native lectin was determined to be 300 kDa by gradient polyacrylamide gel electrophoresis under nondenaturing conditions. On SDS-polyacrylamide gel electrophoresis, the lectin gave a single protein band with molecular masses of 19 and 38 kDa in the presence and absence of 2-mercaptoethanol, respectively. CJA-B contained mannose, N-acetylglucosamine, xylose, and fucose in the molar ratio of 3.0:1.6:1.2:1.1. The protein required calcium ions for hemagglutinating activity and showed specificities for α-galactosyl and α-glucosyl residues. Studies on hemagglutination inhibition by Synsorbs, which are synthetic oligosaccharides coupled chemically to crystalline silica, showed that the lectin mainly interacts with Galα1-3Gal.抄録全体を表示PDF形式でダウンロード (1404K) -
Shoji Tsuji, Toshio Arias, Susumu Ando, Yasukazu Tanaka, Kazuo Kon, To ...1991 年 109 巻 5 号 p. 722-727
発行日: 1991年
公開日: 2008/11/18
ジャーナル フリーTwo major oligosaccharides were isolated from the urine of a patient with type 3 GM1 gangliosidosis. From structural studies including compositional sugar analysis, fast-atom bombardment mass spectrometry, direct-inlet chemical ionization mass spectrometry, methylation analysis, chromium trioxide oxidation, and proton magnetic resonance spectroscopy, their structures were deduced to be as follows:
oligosaccharide 1 Galβl→4GlcNAcβ1→2Manα1→3Manβ1→4GlcNAc
Galβ1→4GlcNAcβ1→2Manα1→6
Oligosaccharide 2 Galβ1→3GlcNAcβ1→3Galα1→4Glc
Fucα1→4 Fucα1→3
Both oligosaccharides have β-linked galactose at the non-reducing ends. Oligosaccharide 1 is one of the most common urinary oligosaccharides found in type 1 and type 2Gm1, gangliosidosis. Oligosaccharide 2, lacto-N-difucohexaose II, has not been described in the urine of GM1, gangliosidosis patients. Excretion of oligosaccharide 1 in the type 3 patient was much less than that of a type 2 patient. Thin-layer chromatographic analysis revealed that the excretion of oligosaccharides with higher molecular weight than that of oligosaccharide 1 (octasaccharide) in the type 3 patient was much less than that of a type 2 patient, raising the possibility that the mutant β-galactosidase of type 3 GM1, gangliosidosis can still act to some extent on higher molecular weight oligosaccharides containing β-linked galactose at the non-reducing end.抄録全体を表示PDF形式でダウンロード (2910K) -
Yuji Ueda, Noboru Yumoto, Masanobu Tokushige, Kouichi Fukui, Hiroaki O ...1991 年 109 巻 5 号 p. 728-733
発行日: 1991年
公開日: 2008/11/18
ジャーナル フリーTwo distinct types of fumarase were purified to homogeneity from aerobically grown Escherichia coli W cells. The amino acid sequences of their NH2-terminals suggest that the two enzymes are the products of the fumA gene (FUMA) and fumC gene (FUMC), respectively. FUMA was separated from FUMC by chromatography on a Q-Sepharose column, and was further purified to homogeneity on Alkyl-Superose, Mono Q, and Superose 12 columns. FUMA is a dimer composed of identical subunits (Mr=60, 000). Although the activity of FUMA rapidly decreased during storage, reactivation was attained by anaerobic incubation with Fe2+ and thiols. Studies on the inactivation and reactivation of FUMA suggested that oxidation and the concomitant release of iron inactivated the enzyme in a reversible manner. While the inactivated FUMA was EPR-detectable, through a signal with g_??_=2.02 and g_??_=2.00, the active enzyme was EPR-silent. These results suggested FUMA is a member of the 4Fe-4S hydratases represented by aconitase. After the separation of FUMC from FUMA, purification of the former enzyme was accomplished by chromatography on Phenyl-Superose and Matrex Gel Red A columns. FUMC was stable, Fe-independent and quite similar to mammalian fumarases in enzymatic properties.抄録全体を表示PDF形式でダウンロード (661K) -
Kyosuke Sato, Yasuzo Nishina, Kiyoshi Ship, Hiromasa Tojo, Michihiko T ...1991 年 109 巻 5 号 p. 734-740
発行日: 1991年
公開日: 2008/11/18
ジャーナル フリーThe association process of FAD and apo-electron-transferring flavoprotein (apoETF) from hog kidney was investigated. The reaction schemes which involve the associationdissociation of the protein species could be excluded by the light scattering data, which indicated that the molecular weights of apoETF and holoETF are identical. The binding reaction between FAD and a large excess of apoETF was monophasic and obeyed pseudofirst order kinetics. On the other hand, the reaction between apoETF and a large excess of FAD was biphasic: the fast phase obeyed a pseudo-first order reaction, and the rate of the slow phase was almost independent of FAD concentration. These results suggest the existence of two different forms of apoETF, as represented in the following reaction scheme:
A*k+2→←k-2A, A+Fk+1→←k-1H,
where “F” is FAD, “H” is holoETF, and “A*” and “A” are the different forms of apoETF. The kinetic parameters were determined as k+1=3.9×104 M-1•s-1, k-1 _??_10-5 s-1 k+2=1.0×10-3 s-1, and k-2=3.1×10-3 s-1, in 50mM potassium phosphate buffer, pH 7.6, containing 0.3mM EDTA, and 5% v/v glycerol, at 7°C. The elution patterns of apoETF on molecular sieve chromatography were very different from that of holoETF although the true molecular weights were identical. This result suggests that the structure of apoETF differs greatly from that of holoETF.抄録全体を表示PDF形式でダウンロード (704K) -
Nobuko Nakamura, Shinji Satomura, Shuji Matsuura, Kazuo Murakami1991 年 109 巻 5 号 p. 741-745
発行日: 1991年
公開日: 2008/11/18
ジャーナル フリーFluorogenic peptide substrates were synthesized in which amino acid residues corresponded to the C-terminal and the N-terminal sides of the site of human angiotensinogen cleaved by renin. Compared with the synthetic substrates of renin previously reported, these fluorogenic substrates had practical advantages in that their digestion products could be rapidly separated and sensitively detected by high-pressure liquid chromatography with a fluorescence detector. The recombinant human renin and human plasma split Leu-Val, which cleavage site is similar to that in human angiotensinogen. The kinetic parameters of the reaction of renin using these substrates were calculated. There seemed to be at least eight subsites in the active site of recombinant human renin, to judge from the enzyme-substrate binding characteristics. The two histidine residues (S5 and S'3) in the octapeptide His-Pro-Phe-His-Leu-Val-Ile-His were important in the enzyme action.抄録全体を表示PDF形式でダウンロード (496K) -
Yuji Goto, Nobuko Okamura, Saburo Aimoto1991 年 109 巻 5 号 p. 746-750
発行日: 1991年
公開日: 2008/11/18
ジャーナル フリーAlthough the conformational change occurring in proteins upon ATP binding is important in many biological reactions, the mechanism by which ATP binding induces the confor-mational change is unknown. We found that ATP induces acid-unfolded (pH 2) ferricytochrome c or apomyoglobin to adopt a compact structure with a significant amount of α-helix and increased hydrophobicity. A very similar conformational transition was observed at neutral pH for an amphiphilic model polypeptide. The effectiveness of various adenine nucleotides in inducing the conformational transition was found to be proportional to their phosphate group contents, i.e., adenosine tetraphosphate ⟩ ATP ⟩ ADP ⟩ AMP. These results should be important when considering the mechanism of the ATP-induced conformational change in proteins during various biological reactions.抄録全体を表示PDF形式でダウンロード (487K) -
Hiroshi Ohmiya, Tohru Kanazawa1991 年 109 巻 5 号 p. 751-757
発行日: 1991年
公開日: 2008/11/18
ジャーナル フリーWe previously showed that A23187 in high ionophore/protein ratios almost completely inhibits the sarcoplasmic reticulum Ca2+-ATPase [Hara, H. & Kanazawa, T. (1986) J. Biol. Chem. 261, 16584-16590]. In an attempt to obtain information on the mechanism of this inhibition, the effects of A23187 on conformational changes involved in the Ca2+ -induced activation of the enzyme were investigated. The purified enzyme from sarcoplasmic reticulum of rabbit skeletal muscle as well as the purified enzyme labeled with fluorescein 5-isothiocyanate (FITC) were preincubated with A23187 in the absence of Ca2+ at pH 7.0 and 0°C for 45min. The activation of the enzyme following addition of CaCl2 was assessed by determining the capacity for rapid formation of phosphoenzyme from ATP. This activation was strongly inhibited by the preincubation with A23187. This indicates that the previously observed inhibition of the Ca2+-ATPase is mostly due to hindrance of the Ca2+-induced activation of the enzyme. In the control, in which the FITC-labeled enzyme was preincubated without A23187, the fluorescence intensity of the bound FITC decreased in a biphasic manner upon addition of CaCl2. The first rapid phase of this fluorescence drop was unaffected by A23187, whereas its second slow phase was almost completely inhibited by this drug. These results show that the Ca2+-dependent conformational change is biphasic and that the second slow phase (but not the first rapid phase) of this conformational change is inhibited by A23187. This suggests that the observed inhibition of Ca2+ activation is attributed to hindrance of the second slow phase of the Ca2+-dependent conformational change.抄録全体を表示PDF形式でダウンロード (741K) -
Seiji Nakamura, Takashi Sakurai, Yoshiaki Nonomura1991 年 109 巻 5 号 p. 758-762
発行日: 1991年
公開日: 2008/11/18
ジャーナル フリーThe gizzard tropomyosin molecule is composed of two subunits at 1:1 molar ratio. Possible composites of the tropomyosin molecule are two kinds of homodimer (one for each subunit), a heterodimer of two subunits, or a mixture of heterodimer and homodimer(s). We tried to evaluate the native subunit composition of gizzard tropomyosin by cross-linking experiments and immunological methods using specific antibodies to each subunit. For the cross-linking experiment we used dimethyl suberimidate, an amino group-specific cross-linker, in the presence of dithiothreitol to avoid artificial oxidative intersubunit cross-linking. When gizzard tropomyosin was cross-linked, it generated several products which might correspond to dimers formed by intersubunit cross-linkage. When the reaction was carried out for a long time, non-cross-linked subunits completely disappeared and two or three major cross-linked products arose. All of these cross-linked products were recognized by both of the specific antibodies to each subunit. These results indicated that the predominant part, if not all, of gizzard tropomyosin is present as heterodimer.抄録全体を表示PDF形式でダウンロード (1583K) -
Toshitsugu Kurotsu, Kazuko Hori, Masayuki Kanda, Yoshitaka Saito1991 年 109 巻 5 号 p. 763-769
発行日: 1991年
公開日: 2008/11/18
ジャーナル フリーGramicidin S synthetase 2 (GS2) derived from Bacillus brevis is a multifunctional single polypeptide (Mr 280, 000) with a 4' -phosphopantetheine residue covalently bound to the enzyme. When GS2 was treated with trypsin or chymotrypsin, fragments with some activity were liberated. The molecular mass of the L-proline activating fragment was 114 kDa on SDS-PAGE. This fragment, when incubated with gramicidin S synthetase 1 (GS1) in the presence of phenylalanine and proline, produced D-Phe-L-Pro dipeptide. The fragment accepted D-phenylalanine from GS1 in the absence of L-proline. The L-proline activating fragment was shown to lack pantothenic acid by microbiological assay. On the other hand, the L-leucine activating fragment, which was partially purified, contained a large amount of pantothenic acid, although it did not form the D-Phe-L-Pro dipeptide. These results indicate that the L-proline activating site is located near an acceptor site for D-phenylala-nine on GS2, but that it is not adjacent to a 4'-phosphopantetheine group. The N-terminal sequence (15 amino acid residues) of the L-proline activating fragment obtained by trypsin treatment was identical with that of GS2, indicating that the L-proline activating site is located at the N-terminus of the native synthetase. The N-terminal sequence of GS2 has been matched with the amino acid sequence deduced from the nucleotide sequence 71 bp downstream of the stop codon of the GS1 gene except that the first initiator methionine was not detected.抄録全体を表示PDF形式でダウンロード (2113K) -
Hideo Sawada, Akira Hara, Mari Ohmura, Toshihiro Nakayama, Yoshihiro D ...1991 年 109 巻 5 号 p. 770-775
発行日: 1991年
公開日: 2008/11/18
ジャーナル フリーThe kinetic mechanism of NADP+ -dependent 3α-hydroxysteroid dehydrogenase and NAD+ -dependent 3α(17β)-hydroxysteroid dehydrogenase, purified from hamster liver cytosol, was studied in both directions. For 3α-hydroxysteroid dehydrogenase, the initial velocity and product inhibition studies indicated that the enzyme reaction sequence is ordered with NADP+ binding to the free enzyme and NADP+ being the last product to be released. Inhibition patterns by Cibacron blue and hexestrol, and binding studies of coenzyme and substrate are also consistent with an ordered bi bi mechanism. For 3α(17β)-hydroxysteroid dehydrogenase, the steady-state kinetic measurements and sub-strate binding studies suggest a random binding pattern of the substrates and an ordered release of product; NADH is released last. However, the two enzymes transferred the pro-R-hydrogen atom of NAD(P)H to the carbonyl substrate.抄録全体を表示PDF形式でダウンロード (562K) -
Kazuko Ohgi, Hiroyuki Horiuchi, Hideaki Watanabe, Masamichi Takagi, Ke ...1991 年 109 巻 5 号 p. 776-785
発行日: 1991年
公開日: 2008/11/18
ジャーナル フリーThe full-length cDNA encoding RNase Rh, which is secreted extracellularly by Rhizopus niveus, was isolated and its nucleotide sequence was determined. It was placed under control of the promoter of the glyceraldehyde 3-phosphate dehydrogenase gene of Saccharomyces cerevisiae in a high expression vector in yeast. Since yeast cells transformed by this plasmid poorly secreted RNase into the medium, the plasmid pYE RNAP-Rh was constructed, in which the signal sequence of RNase Rh was replaced by the prepro-sequence of aspartic proteinase-I, one of the extracellular enzymes secreted by R. niveus. Yeast cells harboring pYE RNAP-Rh produced RNase efficiently (ca. 40μg/m1) into the medium. The product was a mixture of six enzymes (RNase RNAP-Rhs) having 3, 5, 9, 13, 14, and 16 additional amino acid residues attached to the amino terminus of the mature RNase Rh. The major product was the RNase with three additional amino acids at the amino terminus. Limited digestion of RNase RNAP-Rhs with staphylococcal V8 protease succeeded in shortening the various lengths of extra amino acid residues attached to the amino terminus of RNase Rh, yielding an RNase that has 3 additional amino acids at the amino terminus. It has been named RNase RNAP-Rh. The RNase RNAP-Rh showed the same specific activity and CD spectra as those of RNase Rh, suggesting that the two have similar conformations to each other around aromatic amino acid residues and the peptide backbone.抄録全体を表示PDF形式でダウンロード (3553K) -
Yukie Okabe, Naoko Katayama, Masanori Iwama, Hideaki Watanabe, Kazuko ...1991 年 109 巻 5 号 p. 786-790
発行日: 1991年
公開日: 2008/11/18
ジャーナル フリーTwo lectins with RNase activity obtained from eggs of Rana catesbeiana and R. japonica and RNase obtained from R. catesbeiana liver show 65-83% protein homology. The base specificity of these frog proteins was studied with 8 dinucleoside phosphates as substrates and 8 nucleotides as inhibitors. The base specificities of the B1 and B2 sites of these proteins are U>C and G>U>A, C, respectively. The three frog proteins are more resistant than RNase A to heat treatment, guanidine-HC1 and pH-induced denaturation; i. e., they retain their native conformation up to at least 70°C at pH 7.5. Differences in stability and base specificity among RNase A and the three frog proteins are discussed in relation to the primary structures. Although the two lectins agglutinate tumor cells (e. g., Ehrlich, S-180 and AH109A ascites carcinoma cells), the liver RNase has no such activity. Agglutination of AH109A cells by the two lectins is inhibited by nucleotides. Our results indicate that the agglutination sites are not identical with, but are related to, the active sites of the three frog proteins.抄録全体を表示PDF形式でダウンロード (537K) -
Kenzi Suzuki, Tomoharu Gomi, Eiji Itagaki1991 年 109 巻 5 号 p. 791-797
発行日: 1991年
公開日: 2008/11/18
ジャーナル フリーSalicylate hydroxylase [EC 1.14.13.1] from Pseudomonas putida catalyzes the hydroxylation of salicylate, and also o-aminophenol, o-nitrophenol, and o-halogenophenols, to catechol. The reactions with these o-substituted phenols comprise oxygenative deamination, denitration, and dehalogenation, respectively. The reaction stoichiometry, as to NADH oxidized, oxygen consumed, and catechol formed, is 2:1:1, respectively. The mechanisms for the deiodination and oxygenation of o-iodophenol were investigated in detail by the use of I+-trapping reagents such as DL-methionine, 2-chlorodimedone, and L-tyrosine. The addition of the traps did not change the molar ratio of catechol formed to NADH oxidized, nor iodinated traps produced were in the incubation mixture. The results suggest that I+ was not produced on the deiodination in the hydroxylation of o-iodophenol. On the other hand, L-ascorbate, L-epinephrine, and phenylhydrazine increased the molar ratio. o-Phen-ylenediamine decreased it, being converted to phenazine. This suggests that o-benzo-quinone is formed in the oxidation of o-iodophenol as a nascent product. The quinone was detected spectrophotometrically by means of the stopped-flow method. Kinetic analysis of the reactions revealed that o-benzoquinone is reduced nonenzymatically to catechol by a second molecule of NADH. A mechanism of elimination for the ortho-substituted groups of substrate phenols by the enzyme is proposed and discussed.抄録全体を表示PDF形式でダウンロード (741K) -
1991 年 109 巻 5 号 p. 798
発行日: 1991年
公開日: 2008/11/18
ジャーナル フリーPDF形式でダウンロード (23K)
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