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The greening of etiolated bean leaves I. The initial photoconversion process

BBA - Bioenergetics 1971年第1期226卷 113-127页

作者： Thorne, S.W. Australia

1. During the early stages of the initial photoconversion of the etiolated leaf at 20°, a dark stable intermediate photoproduct appears with a fluorescence peak at 674 nm at 77°K. 2. With E the excitation and f the emission peaks at 77°K, the sequence of fluorescence at photoconversion is protochlorophyllide (E650, f655) →I Intermediate (E668, f674) →II chlorophyllide (E678, f687) →III chlorophyllide (E682, f694) →IV chlorophyll (E672, f680). Shifts I and II are photoactivated, whilst Shifts III and IV occur in the dark and correspond to those described by absorption spectroscopy. 3. Protochlorophyllide is present in the leaf in molecular groups, and spectra show that at fractional (approx. 10%), partial (approx. 40%) or full photoconversion the same sequence of fluorescence is observed. Excitation spectra show that energy absorbed by protochlorophyllide is transferred to each of the forms of chlorophyll in the sequence with almost identical efficiency, indicating that transposition or diffusion of chlorophyll away from the protochlorophyllide complex is not the cause of the dark Shifts III or IV. Energy transfer to chlorophyll f680 after fractional or partial photoconversion does however cease after a long dark time at 20°. 4. from the appearance of the intermediate f674, it is determined that a fundamental group size of protochlorophyllide in vivo is of the order 20 molecules. 5. The intermediate f674 gives chlorophyll a after dark ethanol extraction from the leaf. The photoconversion rate for the intermediate f674 is however twice the rate for chlorophyllide f687, suggesting that photoconversion is a two-step, two-photon process in vivo. © 1971.

关键词： peak wavelengths stated in nm the method of measurement being indicated by the prefix A for absorbance E for fluorescence excitation and f for fluorescence emission

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IMMUNOCHEMICAL COMPARISONS Of 3 AVIAN OVALBUMINS

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COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY 1971年第3B期38卷 513-+页

作者： WEINTRAUB, MS SCHLAMOWITZ, M Department of Biochemistry The University of Texas M.D. Anderson Hospital and Tumor Institute at Houston Houston Texas 77025 USA

1. 1. Schematic immunochemical models of chicken, turkey and duck ovalbumins have been constructed from data obtained from reactions with goat IgG antibodies to chicken and turkey ovalbumins. 2. 2. Chicken and turkey ovalbumins each have an f -valence of 6, 5 being common to both and 4 or 5 are common to duck ovalbumin. 3. 3. The phylogenetic relationship implicit in these results is consistent with taxonomic classification.

关键词： Ovalbumins avian chicken turkey duck immunodiffusion precipitin reactions f -Valence schematic immunologic models phylogeny Gallus domesticus Meleagris gallopavo Anas platyrhynochos domesticus

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ELECTROMAGNETIC THEORY Of HETEROSTRUCTURE INJECTION LASERS

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SOLID-STATE ELECTRONICS 1971年第9期14卷 865-+页

作者： ADAMS, MJ CROSS, M Department of Applied Mathematics and Mathematical Physics University College Cardiff Wales

A theoretical study has been made of the wave-guiding properties of GaAs-Al x Ga 1−x As heterostructure injection lasers. The electromagnetic field distributions and far-field radiation patterns of these devices have been calculated by solving Maxwell's equations for a three-layer wave-guide with complex dielectric constants in each region. The theory also yields threshold currents and external quantum efficiencies as functions of the principal laser parameters—temperature, doping, alloy composition x in the Al x Ga 1−x As regions, active region thickness, and cavity length. This permits detailed comparison of the theoretical results with experiment, and hence further estimates of optimal laser structures. In particular the variation of laser threshold with active region thickness (and the existence of an optimum thickness) in single heterostructures is sucessfully accounted for by the theory. for double heterostructures with the same alloy composition in each passive region, there exists no optimum active region thickness, and hence the lowest thresholds can be obtained by making these structures as thin as possible. Une étude théorique a été menée des propriétés de guide d'ondes de lasers d'injection à hétérostructure GaAs-Al x Ga 1−x As. Les distributions de champ électromagnétique et les dessins de radiation loin du champ de ces dispositifs ont été calculés en résolvant les équations de Maxwell pour un guide d'onde à trois couches avec des constantes diélectriques complexes dans chaque région. La théorie fournit également les courants de seuil et les efficacités quantiques externes en fonction des paramètres principaux du laser—température, doping, composition de l'alliage x dans les régions Al x Ga 1−x As. épaisseur de la région active et longueur de la cavité. Ceci permet une comparaison détaillée des résultats théoriques avec l'expérience, et ainsi des évaluations supplémentaires de structures optimales de lasers. En particulier la théorie explique avec succè

关键词： c velocity of light E photon energy E Geff effective energy gap in the active region G Gn energy gap in the n -type region G Gp energy gap in the p -type region E m photon energy corresponding to the peak of the stimulated emession rate E o band tail parameter for the absorption coefficient E o band tail parameter for the absorption coefficient E on energy gap in the n -type region E op energy gap in the p -type region C i electric field in region i f n fermi-level measured relative to the band edge for n -type material f p fermi-level measured relative to the band edge for p -type material h Planck' constant divided by 2π H i magnetic field in region i j th threshold current density K Bolzmann's constant L cavity length M integer characterising the longitudinal model number in the cavity m c effective mass of the electrons in the conduction band m v effective mass of the holes in the valence band n concentration of electrons in the conduction band N integer characterising the transverse mode numberin the cavity N A concentration of acceptors in the p -type region N D concentration of acceptors in the n -type region p concentration of holdes in the valence band p i complex propagation constant in the x -direction for the electronmagnetic field in the region i q complex propagation constant in the z -direction of the electromagnetic field R reflectivity of the mirrors at the cavity ends t active region thinckness T temperature x aluminium conent α effective absorption term in the active region, accouting for diffraction loss, free carrier absorption and any other mechanism which may be present α′ diffraction loss α′ t.c. free carrier absorption coefficient α i absorption coefficient in region i ε i complex dielectric constant in region i η degree of asymmetry η ext external quantum efficiency η i internal quantum efficiency θ angle in the x−z plane between the direction of the obseration and the normal to the radiating surface ε i refractive index in region i σ n capture cross-section for free carrier absorption b

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REQUIREMENT fOR GTP IN INITIATION PROCESS ON RETICULOCYTE RIBOSOMES AND RIBOSOMAL SUBUNITS

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PROCEEDINGS Of THE NATIONAL ACADEMY Of SCIENCES Of THE UNITED STATES Of AMERICA 1971年第9期68卷 2246-&页

作者： SHAfRITZ, DA LAYCOCK, DG CRYSTAL, RG ANDERSON, Wf Section on Molecular Hematology National Heart and Lung Institute National Institutes of Health Bethesda Maryland 20014

The requirement for GTP in the initiation process on reticulocyte ribosomes and ribosomal subunits has been examined by studying Met-tRNA(f) binding, ribosome-dependent [gamma-(32)P]GTP hydrolysis, and peptide-bond formation with puromycin. Met-tRNA(f) binding can be obtained with the methylene analogue, 5'-guanylylmethylene diphosphonate, as well as GTP, and it is not inhibited by fusidic acid or several other inhibitors of protein synthesis. This reaction can be performed with the 40S subunit and has the same requirements as the Met-tRNA(f)-binding reaction with washed ribosomes. Ribosome-dependent [gamma-(32)P]GTP hydrolysis can be obtained with the initiation factor M(2A) using either washed ribosomes or the 40S subunit. This reaction is also not significantly inhibited by fusidic acid. Peptide-bond formation between puromycin and Met-tRNA(f), however, is inhibited by fusidic acid, and does not occur if the methylene analogue of GTP is substituted for GTP. These data suggest that the binding of the initiator tRNA to the 40S subunit does not require the hydrolysis of GTP, but that at least one GTP hydrolysis event must occur after Met-tRNA(f) binding in order for the first peptide bond to be formed.

关键词： GDPCP Met-tRNA f initiation factors elongation factors fusidic acid

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ACTIONS Of CARBONYLCYANIDE META-CHLOROPHENYLHYDRAZONE ON ELECTRON TRANSPORT AND fLUORESCENCE Of ISOLATED CHLOROPLASTS

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BIOCHIMICA ET BIOPHYSICA ACTA 1971年第1期245卷 129-&页

作者： HOMANN, PH Department of Biological Science Florida State University Tallahassee Fla. 32 306 U.S.A.

The actions of carbonylcyanide m -chlorophenylhydrazone (CCCP) on photosynthetic electron transport and fluorescence have been studied using isolated pokeweed ( Phytolacca americana ) chloroplasts which often had been uncoupled by EDTA washing or by addition of methylamine. The presence of CCCP markedly enhanced the photoreduction of oxygen by System 1 with or without added electron donors. It is concluded that the decreased steady state level of chloroplast fluorescence after an addition of CCCP was largely due to an increased rate of electron flow through System 1 to oxygen, rather than to an inhibition of System 2. The inhibition of oxygen evolution by moderate amounts of CCCP was only slight initially, but became more severe during illumination. CCCP appeared to divert oxidizing equivalents from System 2 into destructive side reactions. CCCP strongly inhibited the reoxidation of the reduced primary acceptor Q in 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU)-poisoned chloroplasts. A comparative study of similar actions by various electron donors to System 2, and by inhibitors of phosphorylation, failed to reveal a simple mechanism. One has to take into account not only a direct reduction of the oxidized reaction partner of Q − by the added agent, but also its effect on the membrane integrity, and on the interactions between the electron carriers in System 2.

关键词： CCCP carbonylcyanide m -chlorophenylhydrazone DCMU 3-(3,4-dichlorophenyl)-1,1-dimethylurea DCIP 2,6-dichlorophenolindophenol TMPD N , N , N ′, N ″-tetramethyl- p -phenylenediamine Q “quencher”, the primary electron acceptor of System 2 f 0 the invariable fluorescence yield f DCMU the fluorescence yield in the presence of 10 μM DCMU

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The greening of etiolated bean leaves II. Secondary and further photoconversion processes

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BBA - Bioenergetics 1971年第1期226卷 128-134页

作者： Thorne, S.W. Australia

1. Photoconversions in light-dark stages in etiolated bean leaves show that protochlorophyllide is resynthesized to the same level at each stage. 2. Photoconversions 2 and 3 follow the initial photoconversion process, but after Shift IV, chlorophyll (E674, f683) is formed. 3. At fractional or partial Photoconversions 2 or 3, protochlorophyllide transfers energy to chlorophyllides f687 and f694 but not to chlorophyll (E674, f683). 4. Resynthesized protochlorophyllide exists in discrete groups similar to the initial protochlorophyllide, with molecular transposition from these groups taking place at the shift to chlorophyll (E674, f683). © 1971.

关键词： peak wavelengths stated in nm the method of measurement being indicated by the prefix A for absorbance E for fluorescence excitation and f for fluorescence emission

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The effect of guanosine 5′-triphosphate analogues on protein synthesis

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BBA Section Nucleic Acids And Protein Synthesis 1971年第1期228卷 282-288页

作者： Uno, Hitoshi Oyabu, Shintaro Ohtsuka, Eiko Ikehara, Morio Faculty of Pharmaceutical Sciences Osaka University Toyonaka Osaka Japan

four GTP analogues, 6-mercaptoguanosine 5′-triphosphate (I), N2-methylguanosine 5′-triphosphate (II), N2-dimethylguanosine 5′-triphosphate (III) and 8-bromoguanosine 5′-triphosphate, (IV) were synthesized chemical... 详细信息

four GTP analogues, 6-mercaptoguanosine 5′-triphosphate (I), N²-methylguanosine 5′-triphosphate (II), N²-dimethylguanosine 5′-triphosphate (III) and 8-bromoguanosine 5′-triphosphate, (IV) were synthesized chemically and tested for their ability to replace GTP in the cell-free amino acid incorporation system of Escherichia coli. The order of the activity was found to be GTP ≧ II > III > IV > I. Inhibition of GTP action with compounds I and III in the amino acid incorporation into polypeptides was studied. © 1971.

关键词： s 6 GTP 6-mercaptoguanosine 5′-triphosphates m 2 GTP N 2 -methylguanosine 5′-triphosphate m 2 2 GTP N 2 -dimethylguanosine 5′-triphosphate br 8 GTP 8-bromoguanosine 5′-triphosphate fMet-tRNA f N -formylmethionyl-tRNA

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EVIDENCE fOR REQUIREMENT Of METHIONYL TRANSfERRNA MODIfICATION fOR IN-VITRO POLYPEPTIDE INITIATION IN STREPTOCOCCUS-fAECIUM

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BIOCHIMICA ET BIOPHYSICA ACTA 1971年第2期240卷 233-&页

作者： SARIMO, SS PINE, MJ Department of Experimental Therapeutics Roswell Park Memorial Institute Buffalo N. Y. 14203 U.S.A.

Extracts of folate-deficient Streptococcus faecium have been examined for their ability to dispense with the normal requirement of formylation of methionyl-tRNA to initiate polypeptide biosynthesis. [ 35 S]Methionyl-tRNA's prepared from Escherichia coli or S. faecium both require formylation to bind to S. faecium ribosomes in the presence of endogenous mRNA and AUG. formation of the puromycin derivative of the initiator by S. faecium components is similarly formylation dependent. Spermine promotes a further, but non-specific, Mg 2+ -independent ribosomal binding of both methionyl-tRNA and formylmethionyl tRNA. The cell-free system differs from the intact cell which can utilize formylated or unformylated initiator, and from the eucaryote cytoplasm which does not formylate the initiator. A factor of the intact cell of S. faecium is postulated to substitute for formylation of methionyl tRNA for folateless protein initiation.

关键词： fMet-tRNA Met f formylmethionyl ester of formylatable methionine-accepting transfer RNA

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OCCURRENCE Of CYSTEINYL TRANSfER RIBONUCLEIC ACID WITH BLOCKED ALPHA-AMINO GROUP IN RABBIT RETICULOCYTES

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BIOCHIMICA ET BIOPHYSICA ACTA 1971年第2期232卷 289-+页

作者： PAWELEK, J GODCHAUX, W GRASSO, J SKOULTCHI, AI EISENSTADT, J LENGYEL, P Department of Molecular Biophysics and Biochemistry and Department of Microbiology Yale University New Haven Conn. U.S.A.

1. Rabbit reticulocytes or reticulocyte extracts incorporate cysteine into cysteinyl transfer ribonucleic acid (Cys-tRNA) having a blocked α-amino group (X-Cys-rRNA). The lack of a free α-amino group is revealed in the electrophoretic characteristics of X-cysteinyladenosine (X-Cys-A) obtained from X-Cys-tRNA by treatment with pancreatic ribonuclease, and in the failure of the X-Cys-A to react with acetic anhydride. The electrophoretic characteristics of X-Cys-A and its reactivity with diazomethane indicate that the blocking group X might have a free carboxyl group. X-Cys-A does not react with iodoacetate, possibly indicating that its sulfhydryl group is blocked. 2. Both high and low molecular weight fractions of the reticulocyte extract (obtained by fractionation by gel filtration through a Sephadex G-25 column) are needed for converting Cys-tRNA into X-Cys-tRNA. X-Cys-tRNA was not found in Escherichia coli extracts, but E. coli Cys-tRNA is converted to X-Cys-tRNA when added to a reticulocyte extract. 3. Naf is thought to inhibit a step in peptide chain initiation and to lead to the accumulation of initiation complexes ( W. Hoerz and K. S. McCarthy , Proc. Natl. Acad. Sci. U.S. , 63 (1969) 1206). A tRNA species involved in chain initiation in reticulocytes is tRNA Met f . Intact reticulocytes treated with Naf contain about 7 times more X-Cys-tRNA and 4 times more tRNA Met f (at least partially acylated with methionine) bound to ribosomes than control cells. The amount bound to ribosomes of several other aminoacyl-tRNA's tested (including Cys-tRNA), however, decreases upon treatment with Naf. 4. The structure, biosynthesis, and function of X-Cys-tRNA remain to be established.

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THE DISTRIBUTION Of THE fORMATE ACTIVATING ENZYME AND OTHER ENZYMES INVOLVING TETRAHYDROfOLIC ACID IN ANIMAL TISSUES

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COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY 1960年第3期1卷 227-247页

作者： WHITELEY, HR Department of Microbiology University of Washington Seattle USA >Friday Harbor Laboratories Friday Harbor USA

A survey of a number of animals showed that the formate activating enzyme is present in almost all tissues. In invertebrates, the largest amounts of this enzyme were found in the gonads and reproductive products and the smallest amounts were found in muscle and digestive glands, except for Cancer magister . In the few vertebrate species included in this study, the greatest amounts of formate activating enzyme were found in liver tissues. formate activating enzymes isolated from the oöcytes of Schizobranchia insignis , from the ovaries of Pecten caurinus, Balanus nubilis and Cancer magister and from the livers of Sebastodes caurinus and the rabbit were compared with respect to the K M values for the three components of the reaction and for the requirement for divalent metal ions. Some information was also obtained on the pH optimum, the require-metal ions. Some information was also obtained on the pH optimum, the requirement for a reducing agent, and the stability of various enzyme preparations to storage in the cold. The data obtained indicate that the above enzymes are similar to highly purified preparations of formate activating enzyme obtained from bacteria, although some differences were found in the individual K M values, the metal requirements and the stability upon storage. forty-one tissues from a selected group of animals ( Schizobranchia insignis, Nereis brandti, Pecten caurinus, Strongylocentrotus purpuratus, Balanus nubilis, Cancer magister, Sebastodes caurinus, Onchorynchus nerka , the chicken and the rabbit) were examined with respect to the amounts of four additional enzymes (N 10 -formyl tetrahydrofolic acid deacylase, cyclohydrolase, hydroxymethyl tetrahydrofolic acid dehydrogenase, and serine hydroxymethylase) concerned with the synthesis and interconversion of one-carbon derivatives of folic acid. Except for muscle tissue, varying amounts of the four enzymes were found and no correlation could be found between the levels of these enzymes and that

关键词： fH 4 tetrahydrofolic acid fH 2 dihydrofolic acid f folic acid ATP and ADP adenosine tri- and di-phosphate, respectively TPN and TPNH the oxidized and reduced forms of triphosphopyridine nucleotide DPNH the reduced form of diphosphopyridine nucleotide P i inorganic phosphate Tris tris(hydroxy)aminomethane buffer K M Michaelis constant

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