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Volume 85 (1979)
- Issue 6 Pages 1387-
- Issue 5 Pages 1107-
- Issue 4 Pages 887-
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Volume 85, Issue 6
Displaying 1-22 of 22 articles from this issue
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Shonen YOSHIDA, Machiko YAMADA, Sigeo MASAKI1979 Volume 85 Issue 6 Pages 1387-1395
Published: June 01, 1979
Released on J-STAGE: November 18, 2008
JOURNAL FREE ACCESSPurified DNA polymerase β of calf thymus can utilize poly(rA)•oligo(dT) as efficiently as poly(dA)•oligo(dT) or activated DNA as a template-primer. The poly(rA)•oligo(dT)-dependent activity of DNA polymerase β was found to differ markedly from the DNA-depend-ent activity of the same enzyme (with either activated calf thymus DNA or poly(dA)•(dT)10) in the following respects. 1) Poly(rA)-dependent activity was strongly inhibited by natural DNA from various sources or synthetic deoxypolymer duplexes at very low concentrations (less than 0.5 μg/ml) at which the DNA-dependent activity was affected to a much smaller extent, if at all. 2) Poly(rA)-dependent activity was inhibited by N-ethylmaleimide more strongly than DNA-dependent activity measured at 37°C, while it was resistant to this reagent at 26°C. 3) The curves of the activity versus substrate concentration were sigmoidal in the poly(rA)-dependent reaction but hyperbolic in the activated DNA-dependent reaction. A kinetic study suggested that the association of β-enzyme protomers may be required to copy the poly(rA) strand.View full abstractDownload PDF (597K) -
Csaba CSÉKE, László I. HORVÁTH, Pál ...1979 Volume 85 Issue 6 Pages 1397-1404
Published: June 01, 1979
Released on J-STAGE: November 18, 2008
JOURNAL FREE ACCESSSuperoxide dismutase (SOD) was isolated and purified from Anacystis nidulans to near electrophoretic homogeneity. The enzyme has a molecular weight of 37, 500, as determined by gel filtration and SDS-gel electrophoresis. The enzyme molecule consists of two subunits of identical molecular weight. Proton-induced X-ray elemental analysis (PIXE) showed that the SOD of A. nidulans is an iron-containing enzyme; the Fe:enzyme mol ratio was found to be 1. The EPR spectra indicated that the active center contains high-spin ferric ion. Based on quantitative EPR data, we conclude that essentially all iron ions were detected in the EPR experiments and were present in the Fe3+ high-spin form. Since the Fe: enzyme mol ratio was 1, we suggest that each enzyme contains a 1-Fe3+ active center.
Effective g'-values were calculated from computer-simulated spectra and analysis of the g'-value anisotropy of the ±3/2 Kramers doublet made the calculation of crystal field parameters possible. The symmetry of the Fe3+ ion in the SOD molecule was found to be close to rhombic (E/D=0.240).View full abstractDownload PDF (1150K) -
Some Enzymatic Properties and Subunit StructureYoshihiro FUKUMORI, Tateo YAMANAKA1979 Volume 85 Issue 6 Pages 1405-1414
Published: June 01, 1979
Released on J-STAGE: November 18, 2008
JOURNAL FREE ACCESSThe function and the structural features of Chromatium vinosum cytochrome c-552 have been investigated. Cytochrome c-552 has a sulfide-cytochrome c reductase activity and also catalyzes the reduction of elementary sulfur to sulfide with reduced benzylviologen as the electron donor. In the sulfide-cytochrome reduction, horse and yeast cytochromes c act as good electron acceptors, but cytochrome c' or cytochrome c-553(550) purified from the organism does not.
The subunit structure of cytochrome c-552 has been studied. The cytochrome is split by 6M urea into cytochrome and fiavoprotein moieties with molecular weights of 21, 000 and 46, 000, respectively. The fiavoprotein moiety is obtained by isoelectric focusing in the presence of 6M urea and 0.1% β-mercaptoethanol, while the hemoprotein moiety is obtained by gel filtration with Sephacryl S-200 in the presence of 6 M urea and 0.1M KCl. Neither subunit has sulfide-cytochrome c reductase activity. Attempts to reconstitute the original fiavocytochrome c from the subunits have been unsuccessful.View full abstractDownload PDF (1287K) -
Masanobu TOKUSHIGE, Kenji MIYAMOTO, Hirohiko KATSUKI1979 Volume 85 Issue 6 Pages 1415-1420
Published: June 01, 1979
Released on J-STAGE: November 18, 2008
JOURNAL FREE ACCESSNAD-linked glutamate dehydrogenase [EC 1. 4. 1. 2] was detected together with NADP-linked glutamate dehydrogenase [EC 1. 4. 1. 4] and aspartase [EC 4. 3. 1. 1] in Pseudomonas fluorescens cells. The three enzymes were distinctly separated by DEAE-Sephadex column chromatography. The NAD-linked enzyme was extremely thermolabile and was rapidly inactivated even at temperatures as low as 35-40°C. The combined addition of NAD+ and glutamate, however, effectively stabilized the enzyme. The glutamate saturation profile of the NAD-linked enzyme exhibited cooperativity with a Hill coefficient (n) of 1.4. ATP inhibited the enzyme in an allosteric manner, increasing the n value to 2.2. These results suggest a novel type of metabolic regulation shared by the three enzymes in the biosynthesis and catabolism of amino acids.View full abstractDownload PDF (392K) -
A Comparison with Modification of SH GroupsTakashi SHIMIZU1979 Volume 85 Issue 6 Pages 1421-1426
Published: June 01, 1979
Released on J-STAGE: November 18, 2008
JOURNAL FREE ACCESSModification of 14S dynein with TNBS, an amino group-blocking reagent with high specificity, enhanced the ATPase activity up to 1.4 times. If ATP was present during preincubation for the modification, the TNBS-induced enhancement was repressed to 1.1 times. It was found that the presence of ATP caused a decrease in the number of TNP groups incorporated into the protein. On the other hand, modification of SH groups of 14S dynein was confirmed to give rise to only monotonic inhibition.
The 30S dynein ATPase activity increased 3.8-fold for Mg activation and 5.7-fold for Ca activation on treatment with TNBS. The enhancement was greater than that produced by the modification of SH groups. This enhancement of 30S dynein ATPase activity by TNBS treatment was also repressed to some extent by the presence of ATP during preincubation for the modification. However, the inhibition of the ATPase activity at higher concentrations of TNBS was not suppressed by the presence of ATP, whereas ATP-induced protection of the activity was clearly observed in the modification of SH groups at higher concentrations of NEM (Shimizu, T. & Kimura, I. (1977) J. Biochem. 82, 165-173).
Treatment with showdomycin, which is a maleimide derivative of ribose, caused a small enhancement of 30S dynein ATPase activity (up to 1.5-fold). The reason for this small enhancement is discussed in relation to the structures of chemical modifiers and the reactivity of SH groups of 30S dynein.View full abstractDownload PDF (464K) -
Yuji GOTO, Takachika AZUMA, Kozo HAMAGUCHI1979 Volume 85 Issue 6 Pages 1427-1438
Published: June 01, 1979
Released on J-STAGE: November 18, 2008
JOURNAL FREE ACCESSThe kinetics of the refolding reactions of type λ Bence Jones proteins from 4M GuHCl were studied by CD, ultraviolet absorption, and fluorescence spectrophotometry. The kinetics were complex and consisted of at least three phases, an undetectable fast phase, a detectable fast phase, and a slow phase. The slow phase followed first-order kinetics and the three experimental methods used gave similar rate constants for all the Bence Jones proteins (about 3×10-3 S-1). The refolding reaction of VL fragment was too fast to be measured in the present experiments. The refolding process of CL fragment was very similar to those of Bence Jones proteins except that the detectable fast phase was less significant. The rate constant of the slow phase observed for the CL fragment was similar to those of the slow phase observed for Bence Jones proteins. The activation energy of the slow phase was the same for a Bence Jones protein and its CL fragment. These results indicate that the refolding kinetics of the CL domain are very similar to those of isolated CL fragment and that refolding of the VL domain precedes refolding of the CL domain, even though both domains have similar immunoglobulin folds. However, the results of refolding experiments on Bence Jones proteins, and VL and CL fragments in the presence of ANS, as well as other lines of evidence, indicate that the refolding kinetics of the Bence Jones protein molecule cannot be expressed as simple sum of the refolding reactions of isolated VL and CL fragments.View full abstractDownload PDF (927K) -
Daisaku SATOMI1979 Volume 85 Issue 6 Pages 1439-1446
Published: June 01, 1979
Released on J-STAGE: November 18, 2008
JOURNAL FREE ACCESS1. The state of Ca2+ accumulated in mouse brain microsomes in the presence of ATP was investigated using three methods; the Ca2+ selectrode method, the continuous perfusion method and Millipore filtration.
2. With the Ca2+ selectrode method, it appeared that the mechanism of ATP-dependent Ca2+ uptake consists of a Ca2+ transport step and a Ca2+ storage step. It was confirmed by continuous perfusion experiments that Ca2+ accumulated in the presence of ATP may be classified into two types, designated as Ca2+-type I and Ca2+-type II. Call-type I is slowly released on perfusion of cations. On the other hand, Ca2+-type II remains unaffected by perfusion of cations and exchanges with Ca2+ added to the perfusion solution only if ATP is present in the solution.
3. Sudden release of accumulated Ca2+ (Ca2+-type II) occurred on treatments with 0.1% DOC, 0.5% Triton X-100, and 0.1 N HCl, but on treatment with 2mM EGTA, a specific chelator for Ca2+, no efflux of Ca2+-type II was observed.
4. From the results obtained, it was concluded that the sites responsible for Ca2+-type II accumulated in the presence of ATP are clearly distinguishable from ion exchange-type cation binding sites. We propose the existence of other cation binding sites in brain microsomes, with the following properties: (i) in the presence of ATP, Ca2+ in the medium can penetrate to the sites, but in the absence of ATP, no cations (Mg2+, Ca2+, Na+, K+, etc.) can enter the sites; (ii) the intact structure of the binding sites is readily disrupted by treatment with detergents. A model for ATP-dependent Ca2+ uptake in brain microsomes is proposed.View full abstractDownload PDF (604K) -
Shiro IKAWA, Minoru TAKITA, Michio OGURA1979 Volume 85 Issue 6 Pages 1447-1452
Published: June 01, 1979
Released on J-STAGE: November 18, 2008
JOURNAL FREE ACCESSCholesterol: oxygen oxidoreductase [EC 1.1.3.6] from Brevibacterium sterolicum (ATCC 21387) was found to catalyze the oxidation of steroids such as sterols, steroid hormones, and bile acids having a free C-3β hydroxyl group. However, the enzyme was inactive towards estradiol and estriol and had a weak activity towards steroids with functional groups adjacent to the 3β-hydroxyl group on the steroid nucleus.
Variation in the length of the side chain of 3β-hydroxy steroids had no marked effect on the activity.
3β-Hydroxy bile acids with Δ4 or Δ5 were oxidized to almost the same extent as cholesterol. In contrast, 3β-hydroxy bile acids without Δ4 or Δ5 were oxidized only to the extent of 1.4-2.1%.
3β-Hydroxychol-4 or 5-enoic acid was oxidized in the same way as cholesterol.
This enzyme is useful as a simple tool for identification of 3β-hydroxy groups of bile acids.View full abstractDownload PDF (448K) -
Akiko OSANAI, Toshio SAKAGAMI1979 Volume 85 Issue 6 Pages 1453-1459
Published: June 01, 1979
Released on J-STAGE: November 18, 2008
JOURNAL FREE ACCESSDetailed analyses of phospholipids were performed using male and female rabbit hearts (body weight, 2.5-3.0kg).
No difference between male and female was detected in the lipid-phosphorus content in 1g of wet tissues or in the composition of the phospholipids.
The amounts of the diacyl-, alkenyl-acyl-, and alkyl-acyl-components in cholinephosphoglyceride (PC) were 57%, 40%, and 3%, respectively. The results were the same in both male and female. The amount of the diacyl type of ethanolaminephospholipid (PE) was higher than that of the alkenyl-acyl type in the male (55%, 43%), but the contents of these two components were the same in the female rabbit (49%). The amounts of the alkyl-acyl types were about 3% in both the male and female.
The main difference between the male and female rabbit hearts was in the amount of C18:1 and C18:2 acids in PC, i.e., more C18:1 than C18:2 was detected in the male, whereas the reverse was the case in the female. The fatty aldehyde compositions of the alkenyl-acyl type PC were a little different from each other. Less C16:0 and more C18:0 and C18:1 aldehyde were observed in the male than in the female, while no difference between male and female was observed in the fatty acid and fatty aldehyde compositions of PE.
The fatty acid compositions at the 1-and 2-positions of diacyl- and alkenyl-acyl type PC and PE were analyzed.
The fatty acid composition of the diacyl type PC at the 2-position and that of the alkenyl-acyl type were similar except that more C18:1 and less C20:4 were found in the former in both the male and female rabbits. Different ratios of C18:1 to C18:2 between the male and female were also detected in these two fractions.
The fatty acid composition of diacyl type PE at the 2-position and that of the alkenylacyl type were similar except that more C18:0 was observed in the former than in the latter, and small but significant amounts of C20:5 and C22:3-6 were clearly present in the latter, in contrast to the former, in both the male and female.
As regards the fatty acid composition of the diacyl type compounds at the 1-position, no difference was observed in PC between the male and female, while more C16:0 and less C18:0 was found in PE in the male than in the female.View full abstractDownload PDF (517K) -
Tsutomu UNEMOTO, Maki HAYASHI1979 Volume 85 Issue 6 Pages 1461-1467
Published: June 01, 1979
Released on J-STAGE: November 18, 2008
JOURNAL FREE ACCESSThe site of Na+-dependent activation in the respiratory chain of the marine bacterium, Vibrio alginolyticus, was investigated. The respiratory chain system contained ubiquinones (Q), menaquinones (MK), cytochromes b(560), c(553), d(630), and o(560). The membrane-bound and partially purified NADH dehydrogenase was stimulated 2- to 3-fold by the addition of 0.2M Na+ or K+ and no specific requirement for Na+ was observed in this reaction step. The cytochrome oxidase showed no requirement for monovalent cations. The respiratory activity (NADH oxidase) of the membrane was lost on removal of the quinones, and the reincorpora-tion of authentic Q-10 or MK-4 restored the activity. The rate of MK-4 reduction by NADH (menaquinone reductase) as measured using MK-4 incorporated membrane was activated by Na+, but only slightly by K+. The apparent Ka for Na+ was 78mM for both menaquinone reductase and NADH oxidase. The requirement for Na+ of menaquinone reductase was greatly reduced in the presence of 0.2M is K+. Ubiquinone reductase as measured by using Q-10 incorporated membrane was also activated more effectively by Na+ than by K+ These results strongly suggested that the site of Na+-dependent activation in the respiratory chain of marine V. alginolyticus was at the step of NADH: quinone oxidoreductase.View full abstractDownload PDF (542K) -
V. The Structure of a Novel Ceramide Octasaccharide Containing Mannose-6-Phosphate Found in the Bivalve, Corbicula sandaiOsamu ITASAKA, Taro HORI1979 Volume 85 Issue 6 Pages 1469-1481
Published: June 01, 1979
Released on J-STAGE: November 18, 2008
JOURNAL FREE ACCESSA ceramide octasaccharide containing mannose-6-phosphate was isolated from the freshwater bivalve Corbicula sandai by solvent fractionation, followed by two types of silicic acid column chromatography, and finally QAE-Sephadex column chromatography. The structural analysis involved the following steps. (a) Gas-liquid chromatography of the component sugars, fatty acids, and long-chain bases. (b) Degradation with HC1 and HF to elucidate the sugar sequence. (c) Permethylation analysis coupled with GC-MS to identify the positions of the glycosidic linkages between the sugar units. (d) Chromium trioxide oxidation to determine the anomeric configuration. (e) Smith degradation to determine the site of linkage of the ethanolamine residue.
The structure of this novel glycolipid was determined to be: 4-O-MeGalp(β1→3)-GalNAcp (β1→3) Fucp (α1→4) GIcNAcp (β1→2) Manp (α1→3) [Xylp (α1→2)] [2-aminoethyl-phosphoryl (→6)] Manp (β1→4) Glcp (β1→1) ceramide. It is very interesting that fucose was found to be internally linked in this sugar chain. To our knowledge, this is the first example of internal fucose in a glycolipid. The ceramide moiety consisted of normal saturated fatty acids, among which stearic acid was predominant, and contained C16- and C18-4-sphingenine as the major long-chain bases.View full abstractDownload PDF (1742K) -
Kazuo HOSOI, Shizuko KOBAYASHI, Masahiko HIRAMATSU, Naomi MINAMI, Taka ...1979 Volume 85 Issue 6 Pages 1483-1488
Published: June 01, 1979
Released on J-STAGE: November 18, 2008
JOURNAL FREE ACCESSN-Acetyl β-glucosaminidase [β-2-acetamido-2-deoxy-n-glucoside acetylamido-deoxygluco-hydrolase; EC 3. 2. 1. 30] in the submandibular gland of mice was found to be androgen-depend-ent; the specific activities in males, females, and castrated males were 0.25, 0.11, and 0.11unit/mg protein, respectively. The activities in females and castrated males were increased to the level of normal male mice by testosterone injection. Injections of progesterone and 17β-estradiol hardly affected the activity in males. In both males and females, the enzyme activity was detected in the convoluted tubular cells, not in acinous cells. The results of isoelectric focusing have shown that one enzyme having an isoelectric point of 9.0 is present in the glands of both sexes, indicating that the enzyme remains after castration and that the increases caused by testosterone represent the same molecular species. In addition, it was shown that the saliva from both sexes contained significant activity of N-acetyl β-gluco-saminidase, which also changed depending on the androgenic state of the animals. Most of the salivary activity was shown to originate from the submandibular gland, since the extirpation of this gland resulted in a significant decrease of the salivary activity.View full abstractDownload PDF (996K) -
Edward A. LEBOWITZ, Roger COOKE1979 Volume 85 Issue 6 Pages 1489-1494
Published: June 01, 1979
Released on J-STAGE: November 18, 2008
JOURNAL FREE ACCESSMyosin was purified from ovine uterine smooth muscle. The 20, 000 dalton myosin light chain was phosphorylated to varying degrees by an endogenous Ca2+ dependent kinase. The kinase and endogenous phosphatases were then removed via column chromatography. In the absence of actin neither the size of the initial phosphate burst nor the steady state Mg2+-dependent ATPase activity were affected by phosphorylation. However, phosphorylation was required for actin to increase the Mg2+-dependent ATPase activity and for the myosin to superprecipitate with actin. Ca2+ did not affect the Mg2+-dependent ATPase activity in the presence or absence of actin or the rate or extent of superprecipitation with actin once phosphorylation was obtained. These data indicate that: 1) phosphorylation of the 20, 000 dalton myosin light chain controls the uterine smooth muscle actomyosin interaction, 2) in the absence of actin, phosphorylation does not affect either the ATPase of myosin or the size of the initial burst of phosphate and, 3) Ca2+ is important in controlling the light chain kinase but not the actomyosin interaction.View full abstractDownload PDF (1073K) -
Kenzo OHTSUKI, Samuel BARON1979 Volume 85 Issue 6 Pages 1495-1502
Published: June 01, 1979
Released on J-STAGE: November 18, 2008
JOURNAL FREE ACCESS1. Treatment of mouse L cells with mouse interferon resulted in an increase of ribosomal-associated protein kinase activity. The increase was completely blocked by actinomycin-D or cycloheximide, and heterologous human interferon did not induce an increase of protein kinase activity in the mouse L cell system.
2. Partial purification of protein kinases from a high salt wash ribosomal fraction from interferon-treated cells by ion exchange chromatography and glycerol density gradient centrifugation showed that the molecular weight of one of the protein kinases (designated as enzyme I) was 85, 000-90, 000 daltons and that of the other (designated as enzyme II) was 50, 000-55, 000 daltons. The specific activities of enzymes I and II from interferon-treated cells were about 2 and 9 times higher, respectively, than those from untreated cells.
3. For optimal activities, both enzymes required divalent cations such as Mg2+ and Mn2+, and sulfhydryl reagents such as dithiothreitol (DTT). Low concentrations of dsRNA (50-100ng/ml) markedly enhanced the activity of enzyme II, but did not affect the activity of enzyme I. Aminopurine (2mM) and N-ethylmaleimide (5mM) inhibited more than 90% of the activities of these enzymes. Both enzymes phosphorylated calf thymus histone, casein, or purified initiation factor (eIF-2) with [γ-32P] ATP.
4. The eIF-2 activity (binding of eIF-2 with Met-tRNAf and GTP) was significantly inhibited when eIF-2 was preincubated with enzyme II (from interferon-treated cells) in the presence of ATP (1mM). The reduction of eIF-2 activity by enzyme II in the presence of ATP was strongly stimulated by low concentrations of dsRNA (50-100ng/ml), and it was completely prevented by addition of aminopurine (2mM).
5. These findings suggest that the reduction of eIF-2 activity by enzyme II may involve phosphorylation of eIF-2 by this interferon-induced protein kinase in the presence of ATP. The mechanism of inhibition of eIF-2 activity by interferon-induced protein kinase is similar to that of the inhibition of polypeptide chain initiation induced by HRI (cAMP independent protein kinase) in rabbit reticulocyte lysates.View full abstractDownload PDF (649K) -
KAMALUDDIN, Hiroshi YANAGAWA, Fujio EGAMI1979 Volume 85 Issue 6 Pages 1503-1507
Published: June 01, 1979
Released on J-STAGE: November 18, 2008
JOURNAL FREE ACCESSAs reported previously, glycine, serine, aspartic acid, and β-alanine are the predominant amino acids produced from equimolecular formaldehyde and hydroxylamine in a modified sea medium enriched with essential transition metal ions.
The time course of formation of the amino acids and related substances was studied. Among the amino acids, glycine was produced earlier. Urea was produced initially and disappeared rapidly. Formation of cyanide, glycinenitrile, and glycinamide preceded the formation of amino acids.
Probable pathways for the formation of amino acids and urea are suggested.View full abstractDownload PDF (293K) -
Hiroshi NOJIMA, Tairo OSHIMA, Haruhiko NODA1979 Volume 85 Issue 6 Pages 1509-1517
Published: June 01, 1979
Released on J-STAGE: November 18, 2008
JOURNAL FREE ACCESS(1) A glycolytic enzyme, phosphoglycerate kinase [EC 2.7.2.3], was purified from cells of an extreme thermophile, Thermus thermophilus strain HB8. The enzyme was resistant to heat, and no loss of activity was observed after incubation for 10-20 min at 79°C.
(2) Catalytic properties such as pH optimum (pH 6-8.5), kinetic parameters (Km=0.28mM for ATP, 1.79mM for glycerate 3-phosphate), substrate specificity and inhibitors of the enzyme were investigated and compared with those of phosphoglycerate kinase from other sources.
(3) The enzyme protein consists of a single polypeptide chain of molecular weight 44, 600. The isoelectric point is 5.0. The amino acid composition of the enzyme was studied. The contents of ordered secondary structures were estimated to be 29% α-helix and 11% pleated sheet from the circular dichroic spectrum of the enzyme protein.
(4) The fluorescence spectrum of the enzyme protein showed an emission maximum at 320nm when excited at 280nm. The quantum yield was 0.19. Tryptophyl fluorescence was not quenched, in contrast to the fluorescence reported for yeast phosphoglycerate kinase.View full abstractDownload PDF (1269K) -
II. Chemical CompositionKazuo DEGUCHI, Shizue KAWASHIMA, Nobuo UETA1979 Volume 85 Issue 6 Pages 1519-1525
Published: June 01, 1979
Released on J-STAGE: November 18, 2008
JOURNAL FREE ACCESSThe chemical composition of yolk lipoproteins (YLP-1, 2, and 3) was determined. YLP-1, 2, and 3 were quite similar as regards the chemical composition of lipids, proteins, and carbohydrate moieties. Each lipoprotein has an average dry weight composition of lipids (55-72%) and apo-lipoproteins (28-45%) containing protein, hexose, hexosamine, and sialic acid. In each lipoprotein, triacylglycerol is a major lipid component (70-83%), followed by phospholipid (8-16%), cholesterol (free and esterified, 8-10%), and free fatty acid (3-4%). Phosphatidylcholine and phosphatidylserine account for 68-74 % and 16-24 % of the phospholipids, respectively. The fatty acid compositions of total lipids from each lipoprotein are quite similar, with a high degree of unsaturation (63-65%). The carbohydrate content of apolipoproteins from each lipoprotein is remarkably high (27-31% of apo-lipoproteins) and their composition is very simple: mannose and glucosamine are major constituents in the polysaccharide moiety of each lipoprotein and sialic acid is all in the N-glycolyl form. The amino acid compositions of apo-lipoproteins are quite similar in YLP-1, 2, and 3, with high contents of aspartic acid, glutamic acid, threonine, serine, and leucine. Furthermore, a small amount of glycolipids is present in the yolk lipoproteins. They were separated into six components on TLC. All of them are resorcinol-positive, indicating the presence of sialoglycolipids.View full abstractDownload PDF (543K) -
Yoshiyasu YABUSAKI, Tokuzo NISHINO, Nakao ARIGA, Hirohiko KATSUKI1979 Volume 85 Issue 6 Pages 1531-1537
Published: June 01, 1979
Released on J-STAGE: November 18, 2008
JOURNAL FREE ACCESSThe formation of cholesta-7, 24-dien-3β-ol and its activity as a substrate for the sterol sidechain methyltransferase in yeast have not previously been studied. Experiments with acetonepowder extracts of yeast showed that the sterol is formed from zymosterol by Δ8-Δ7 isomerization. However, direct conversion of cholesta-7, 24-dien-3β-ol into zymosterol could not be demonstrated. The reversibility of the reaction was proved by the detection of 3H-incor-poration into cholesta-8-en-3β-ol (with lathosterol as a carrier) from [3H] H2O in the medium.
Incubation of cholesta-7, 24-dien-3β-ol and S-adenosyl-L-[methyl-14C]methionine with the acetone-powder extract resulted in methylation of the sterol to form episterol. Similar incubation of zymosterol gave fecosterol and episterol, suggesting that fecosterol initially formed by the methylation was isomerized to episterol. In intact cells, however, an alternative pathway (zymosterol→cholesta-7, 24-dien-3β-ol→episterol) may also operate. The relative importance of the two pathways is not known.View full abstractDownload PDF (547K) -
Koui TAKAHASHI, Hiroshi SAITO1979 Volume 85 Issue 6 Pages 1539-1542
Published: June 01, 1979
Released on J-STAGE: November 18, 2008
JOURNAL FREE ACCESSChanges in connectin and elasticity of skeletal muscle were determined during post-mortem ageing. The amount of connectin decreased with increasing time of post-mortem storage whereas the rate of the decrease depended on the source of muscles. The loss in elasticity of muscle coincided well with the decrease in connectin contents. Electron microscopically, a network structure between the Z discs vanished when the amount of connectin fell to zero. We have concluded that the continuous net structure of connectin is responsible for about 30% of the total elasticity of living skeletal muscle and its degradation is responsible for postmortem tenderization of meat.View full abstractDownload PDF (731K) -
Takashi ASADA, Gaku ASHIBA, Shizuo WATANABE1979 Volume 85 Issue 6 Pages 1543-1546
Published: June 01, 1979
Released on J-STAGE: November 18, 2008
JOURNAL FREE ACCESS1. It was found that Mg-ATPase of clam foot myosin is strongly activated by calcium or strontium ions and is as sensitive to those divalent cations as the Mg-ATPase and superpre-cipitation of rabbit skeletal acto-clam foot myosin are.
2. It was also found that desensitization and resensitization of clam foot myosin result in the loss of superprecipitation activity with acto-desensitized myosin and in its recovery with acto-resensitized myosin, respectively. However, the ATPase activity in the absence of calcium ions rises with acto-desensitized myosin and falls again with acto-resensitized myosin.
3. It is thus proposed that the primary role of the EDTA-light chain component in calcium regulation is to inhibit myosin-ATPase rather than to inhibit the actin-myosin interaction.View full abstractDownload PDF (274K) -
Hitoshi SUZUKI, Katsuko KAKINUMA1979 Volume 85 Issue 6 Pages 1547-1549
Published: June 01, 1979
Released on J-STAGE: November 18, 2008
JOURNAL FREE ACCESSPotassium superoxide (KO2), which can be dissolved in dimethyl sulfoxide containing crown ether, has been used as a source of O2-• for superoxide reaction systems. We have found that crown ether reacts with thiobarbituric acid (TBA) in the presence of KO2 to form a red pigment, which is a well-known reaction product of lipoperoxide.View full abstractDownload PDF (154K) -
Akio MATSUKAGE, Miwako NISHIZAWA, Taijo TAKAHASHI1979 Volume 85 Issue 6 Pages 1551-1554
Published: June 01, 1979
Released on J-STAGE: November 18, 2008
JOURNAL FREE ACCESSPoly(dT) products which were synthesized depending on (rA)n•(dT)12-18 as a template-primer by mammalian DNA polymerases β and γ were analyzed by alkaline sucrose gradient centrifugation. The size of the population of poly(dT) chains synthesized by DNA polymerase β increased slowly and consistently during incubation up to at least 30min. On the other hand, the product size with DNA polymerase γ reached the final size (7s) within 5min and the number of products increased during further incubation. Comparison of product number per enzyme molecule suggests that DNA polymerase β acts on multiple primers in a distributive fashion while DNA polymerase r completes poly(dT) chains of large size in a one-by-one fashion.View full abstractDownload PDF (296K)
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