bluuebunny/crossref_metadata_2025 huggingface dataset:
INCREASE IN RAT BRAIN TYROSINE HYDROXYLASE ACTIVITY PRODUCED BY ELECTROCONVULSIVE SHOCK
Authors: Musacchio Jose M. , Julou Louis , Kety Seymour S. , Glowinski Jacques
Published: May 2006

A sustained increase in the turnover of norepinephrine coupled with an increased concentration of that amine has, in a previous study, been observed in the brains of rats exposed to electroconvulsive shock twice daily for one week. The phenomenon has been further examined by studying the effects of a similar regimen of electroconvulsive shock upon tyrosine hydroxylase in the brain, since that enzyme appears to be rate-limiting in norepinephrine synthesis. A small (15%) but significant increase in the whole brain enzyme activity was found in the electroshock-treated animals. A significant increase of tyrosine hydroxylase activity was found in the brainstem (24%) and cortex (20%) of such animals.
DNA OF BACTERIOPHAGE PM2: A CLOSED CIRCULAR DOUBLE-STRANDED MOLECULE
Authors: Espejo Romilio T. , Canelo Eliana S. , Sinsheimer Robert L.
Published: May 2006

The DNA molecules isolated from mature bacteriophage PM2 are closed double-stranded rings of a molecular weight of six million. Direct evidence for the circularity and supercoiling of PM2 DNA was obtained by electron microscopy. Other properties, such as sedimentation behavior at neutral and alkaline pH, unusually high buoyant density in alkaline CsCl, and stability upon heating, are consistent with this structure. Only the four common nucleotides are found after hydrolysis and chromatographic analysis of PM2 DNA.
EVIDENCE FOR A PROPOSED INITIATION COMPLEX FOR PROTEIN SYNTHESIS IN RETICULOCYTE POLYRIBOSOME PROFILES
Authors: Hoerz Wolfram , McCarty K. S.
Published: May 2006

Polysomes consisting of 40
S
ribosomal subunits attached to monosomes, disomes, trisomes, and tetrasomes have been isolated for the first time by the use of isokinetic sucrose density gradients. They are formed upon incubation of rabbit reticulocyte lysate in the presence of 10 mM NaF. It is proposed that these structures represent transient initiation complexes for protein synthesis.
COMPARED EFFECTS OF DITHIOTHREITOL ON THE INTERACTION OF AN AFFINITY-LABELING REAGENT WITH ACETYLCHOLINESTERASE AND THE EXCITABLE MEMBRANE OF THE ELECTROPLAX
Authors: Podleski Thomas , Meunier Jean-Claude , Changeux Jean-Pierre
Published: May 2006

p
-(trimethyl ammonium) benzene diazonium difluoroborate (TDF), an affinity-labeling reagent of the acetylcholine receptor site(s), which in the normal cell acts as an irreversible inhibitor becomes a reversible activator after
in vivo
exposure of the electroplax to dithiothreitol (DTT), a disulfide bond reducing agent. After
in vitro
exposure of acetylcholinesterase to DTT, TDF becomes a reversible competitive inhibitor of the enzyme, using indophenyl acetate as the substrate. Both acetylcholinesterase and the macromolecular receptor of acetylcholine thus contain disulfide bonds. Additional experiments with DTT suggest that there might exist several different classes of receptor sites for cholinergic agents in the excitable membrane of the electroplax.
GENETIC FUNCTIONS OF THE CHLOROPLAST OF
Chlamydomonas reinhardi
: EFFECT OF RIFAMPIN ON CHLOROPLAST DNA-DEPENDENT RNA POLYMERASE
Authors: Surzycki S. J.
Published: May 2006

The effect of rifampin, an inhibitor of bacterial DNA-dependent RNA polymerase, was studied in
Chlamydomonas reinhardi
. It was shown,
in vivo
and
in vitro
, that chloroplast-located, but not nuclear, DNA-dependent RNA polymerase is inhibited by this drug. The inhibition of chloroplast RNA polymerase results in the inhibition of chloroplast rRNA synthesis, and thus in the loss of chloroplast ribosomes. The ability to carry out photosynthesis is also lost after prolonged heterotrophic growth in the presence of rifampin, but cell division and chloroplast replication are not affected. It is proposed that chloroplast DNA contains information for chloroplast rRNA, but this DNA does not have the information for chloroplast DNA polymerase. Moreover, the DNA polymerase is not synthesized on chloroplast ribosomes.
In vitro
SYNTHESIS OF DIFFERENT CATEGORIES OF SPECIFIC PROTEIN BY MEMBRANE-BOUND AND FREE RIBOSOMES
Authors: Ganoza M. Clelia , Williams Curtis A.
Published: May 2006

The free and membrane-bound ribosomes of hepatic cells were isolated and used to program protein synthesis in cell-free extracts. Immuno-electrophoretic and radioautographic analysis of the products showed that the membrane-bound ribosomes synthesized serum proteins, whereas ribosomes free of endoplasmic reticulum synthesized specific nonserum liver proteins. After synthesis, the serum proteins remained associated with membrane vesicles, whereas the other liver proteins were found free of cytoplasmic organelles.
THE NEGATIVE CONTROL MECHANISM FOR
E. coli
DNA REPLICATION
Authors: Rosenberg Barbara Hatch , Cavalieri Liebe F. , Ungers Grace
Published: May 2006

Evidence is presented to show that the initiation of DNA replication in
E. coli
555-7 requires synthesis of a protein whose production is correlated with total protein synthesis. Once replication is initiated, however, reinitiation will occur if
all
further protein synthesis is prevented; a small amount of protein synthesis is sufficient to prevent this unregulated reinitiation. This shows that the initiation of DNA replication is under negative control. A mechanism for the control of DNA replication is proposed; in this mechanism a replication repressor is synthesized periodically, while an antirepressor protein is synthesized continuously. Derepression of initiation results after sufficient accumulation of the antirepressor protein, and repression is re-established by repressor synthesis after the initiation of replication.
THE SMALLEST TIME DIFFERENCE THE EYES CAN DETECT WITH SWEEPING STIMULATION
Authors: Békésy Georg von
Published: May 2006

Experiments in hearing showed that a time difference of 0.1 msec between the stimulation of the left and right ear by a similar click was enough to be recognized as a spatial shift of the integrated sound perception. Similar phenomena were obtained for taste stimulation on both sides of the tongue or with an odorous substance introduced to both nostrils. No similar phenomenon was obtained in binocular vision, when a short time difference between the stimulation of both eyes was introduced and the location of the fused image was observed. It was found that this peculiarity for vision could be eliminated when the stimuli for vision were made more identical to the stimuli used for the other sense organs, practically most of which were sweeping stimuli. Sweeping light stimuli with time differences of 0.1 msec between both eyes could be detected as spatial shifts with the same precision as for the other senses. This widens the expected similarities between the different sense organs.
A GENETIC ASSAY FOR MRNA'S OF PHAGE T4
Authors: Jayaraman Ramamirtha , Goldberg Edward B.
Published: May 2006

A method has been developed by which many gene-specific mRNA's in T4-infected cells can be quantitatively assayed. The method involves separation of complementary strands of phage T4 DNA, hybridization of the strands with RNA, digestion of nonhybridized regions of DNA with an endonuclease specific for single-stranded DNA, and assay of protected genetic markers by transformation. It has been shown that the gene γIIB is transcribed early from the light strand and that the gene 21 is transcribed late from the heavy strand.
MAGNETIC RESONANCE STUDIES OF SPIN-LABELED CREATINE KINASE SYSTEM AND INTERACTION OF TWO PARAMAGNETIC PROBES
Authors: Taylor June S. , Leigh John S. , Cohn Mildred
Published: May 2006

Creatine kinase from rabbit muscle has been specifically labeled with a derivative of a nitroxide free radical on the two essential sulfhydryl groups, one per active site. The conformation in the environment of the enzyme-bound free radical and the change in conformation induced upon binding of the substrate, metal adenosine diphosphate, has been monitored by two parameters of the bound spin label, its electron paramagnetic resonance spectrum and its contribution to the proton relaxation rate of water. The specificity in activation of the enzymic reaction of the series of alkaline earth ions, Mg, Ca, Sr, Ba, was not reflected by differences in conformation of the ternary enzyme metal substrate complexes observable with the spin probe. However, with the inhibitory zinc ion, the conformation of ternary complex was distinctly different. The electron paramagnetic resonance spectra of complexes with two paramagnetic probes, namely, spin-labeled enzyme with paramagnetic metal adenosine diphosphate complexes (Mn(II), Ni(II), and Co(II)) revealed a spin-spin interaction between the protein-bound free radical and the paramagnetic metal ions. From the magnitude of the interaction, the distance between the manganous ion and the electron spin of the nitroxide moiety in the MnADP-spin-labeled creatine kinase was estimated to be in the range of 7-10 Å.
THE MECHANISM OF VIRAL CARCINOGENESIS BY DNA MAMMALIAN VIRUSES, VI. A NEW CLASS OF VIRUS-SPECIFIC RNA MOLECULES IN CELLS TRANSFORMED BY GROUP C HUMAN ADENOVIRUSES
Authors: Fujinaga Kei , Piña Magdalena , Green Maurice
Published: May 2006

A new class of virus-specific RNA molecules was found in cells transformed by group C human adenovirus types 2, 5, and 6. RNA isolated from virus-free rat embryo cells transformed by adenovirus 2, 5, and 6 hybridized with all group C adenovirus DNA's (adenovirus 1, 2, 5, and 6) equally well, but not appreciably with group A and B adenovirus DNA's. Most likely no viral genes common to group A, B, and C adenoviruses are transcribed in adenovirus-transformed cells.

Group C adenoviruses are closely related since they share 83 to 93 per cent of their base sequences as shown by DNA-DNA homology measurements. Group C DNA's share only 10 to 26 per cent of their base sequences with group A and B DNA's. Moreover, the shared sequences are not transcribed detectably in adenovirus transformed cells.

Virus-specific RNA isolated from group C transformed cells contains 49 to 51 per cent G + C, but viral DNA's possess a 7 to 9 per cent higher G + C content. These differences suggest that only a portion of the viral genome with an average G + C content of 49 to 51 per cent is transcribed in group C adenovirus transformed cells.
FRACTIONATION OF PHYTOHEMAGGLUTININ, I. PURIFICATION OF THE RNA AND DNA SYNTHESIS-STIMULATING SUBSTANCES AND EVIDENCE THAT THEY ARE NOT PROTEINS
Authors: Goldberg M. L. , Rosenau W. , Burke G. C.
Published: May 2006

We have separated the RNA synthesis-stimulating activity and the DNA synthesis-stimulating activity of extracts of
Phaseolus vulgaris
(phytohemagglutinin) from the erythroagglutinins, leukoagglutinins, and cytotoxic factors. We have shown that the substances stimulating the synthesis of nucleic acids are probably not proteins, since they are not significantly affected by rigorous deproteinization or treatment by trypsin and pronase. Likewise, they do not appear to be nucleic acids, since they are not precipitated by perchloric acid and resist RNase, DNase, and phosphodiesterases. They are probably not carbohydrates, since 98 per cent of the carbohydrate can be removed from a preparation with only a moderate loss in activity. The RNA and DNA synthesis-stimulating activities are probably associated with separate molecules, since they are destroyed by periodate at different rates.
ESTABLISHMENT OF FUNCTIONAL CLONAL LINES OF NEURONS FROM MOUSE NEUROBLASTOMA
Authors: Augusti-Tocco Gabriella , Sato Gordon
Published: May 2006

Clonal lines of neurons were obtained in culture from a mouse neuroblastoma. The neuroblastoma cells were adapted to culture growth by the animal-culture alternate passage technique and cloned after single-cell plating. The clonal lines retained the ability to form tumors when injected back into mice. A striking morphological change was observed in the cells adapted to culture growth; they appeared as mature neurons, while the cells of the tumor appeared as immature neuroblasts.

Acetylcholinesterase and the enzymes for the synthesis of neurotransmitters, cholineacetylase and tyrosine hydroxylase were assayed in the tumor and compared with brain levels; tyrosine hydroxylase was found to be particularly high, as described previously in human neuroblastomas. The three enzymes were found in the clonal cultures at levels comparable to those found in the tumors. Similarly, there were no remarkable differences between the three clones examined.
RATES OF GDP-INDUCED AND GTP-INDUCED DEPOLYMERIZATION AND ISOMERIZATION OF THE BOVINE LIVER GLUTAMATE DEHYDROGENASE-COENZYME COMPLEX: A POSSIBLE CONTROLLING FACTOR IN METABOLIC REGULATION
Authors: Huang Charles Y. , Frieden Carl
Published: May 2006

The rate of the depolymerization of beef liver glutamate dehydrogenase induced by coenzyme and the purine nucleotides guanosine 5′-diphosphate and guanosine 5′-triphosphate, which are potent inhibitors of enzymatic activity, has been measured by rapid light scattering techniques and by absorbancy changes with stop flow. It is shown that the rate constant for this process may vary from several milliseconds to several seconds depending upon the nucleotides used. The widely varying rate constants for the nucleotide-induced depolymerization may serve a role in determining the nature of the regulation of enzyme activity by nucleotides. Depolymerization induced by guanosine 5′-diphosphate in the presence of diphosphopyridine nucleotide is slower than in the presence of triphosphopyridine nucleotide as coenzyme, and this difference is apparently due to the isomerization of the enzyme as a result of diphosphopyridine nucleotide binding to a second, nonactive site. This binding, as well as binding of the coenzyme to the active site, may be conveniently measured by a purine nucleotide-induced spectral shift in the coenzyme absorption spectrum. It is also shown that complete depolymerization of the enzyme in the presence of guanosine 5′-triphosphate is accomplished by about half saturation of the coenzyme active sites (6-8 active “monomer”).
SELECTIVE TRANSLATION OF T4 TEMPLATE RNA BY RIBOSOMES FROM T4-INFECTED
Escherichia coli
Authors: Hsu Wen-Tah , Weiss Samuel B.
Published: May 2006

The present studies indicate that T4 infection induces an alteration in host ribosomes which restricts the translation of host and other T4-unrelated template RNAs but permits normal translation of T4 RNA. A heat-labile factor has been isolated from T4-infected cell ribosomes which, when combined with normal cell ribosomes, confers upon the latter the property of selective T4 template RNA translation.
BIOSYNTHESIS OF THE CHONDROITIN SULFATE-PROTEIN LINKAGE REGION: PURIFICATION AND PROPERTIES OF A GLUCURONOSYLTRANSFERASE FROM EMBRYONIC CHICK BRAIN
Authors: Brandt Alan E. , Distler Jack , Jourdian George W.
Published: May 2006

The present paper describes the purification and properties of a glucuronosyltransferase isolated from 13-day embryonic chick brain. The enzyme catalyzes transfer of glucuronic acid from UDP-glucuronic acid to a series of low and high molecular weight compounds which contain terminal non-reducing β-D-galactose residues. Studies utilizing enzymatically degraded chondromucoprotein as acceptor suggest that the glucuronosyltransferase terminates biosynthesis of the linkage region between protein and polysaccharide of chondromucoprotein.
THE EXTRACELLULAR NUCLEASE OF
Staphylococcus aureus
: STRUCTURES OF THE NATIVE ENZYME AND AN ENZYME-INHIBITOR COMPLEX AT 4 Å RESOLUTION
Authors: Arnone Arthur , Bier C. James , Cotton F. Albert , Hazen Edward E. , Richardson David C. , Richardson Jane S.
Published: May 2006

Independent 4 Å electron density maps calculated for the extracellular nuclease of
Staphylococcus aureus
(based on data from three heavy-atom derivatives) and for a nuclease-thymidine-3′,5′-diphosphate-calcium ion complex (based on a single isomorphous derivative) show about 60 per cent of the chain resolved, including 3½ turns of helix. The pyrimidine ring of the inhibitor fits into a pocket in the enzyme and appears to be parallel to the ring of a tyrosyl residue. Conformational changes can be observed between the nuclease and the nuclease-inhibitor complex, but the two structures seem to be identical over most of the molecule.
FERROMAGNETISM AND SUPERCONDUCTIVITY IN URANIUM COMPOUNDS
Authors: Matthias B. T. , Chu C. W. , Corenzwit E. , Wohlleben D.
Published: May 2006

The intimate correlation between the mechanisms causing magnetism and superconductivity in uranium compounds has been verified again—in novel systems.
CORRELATED EFFECTS OF ECDYSONE AND NEUROSECRETION IN PUPARIUM FORMATION (PUPARIATION) OF FLIES
Authors: Zdarek Jan , Fraenkel G.
Published: May 2006

A neurohormone accelerates the formation and tanning of the fly puparium in the presence of ecdysone. When larvae of
Phormia regina
are divided by ligation into two parts before the critical period, the hind part remains untanned, unless injected with blood from a pupariating larva. This confirms earlier observations and is in contrast to recent data with another genus. When
Sarcophaga bullata
larvae are ligated after the critical period, the anterior part starts to tan about two hours before the posterior part. Injecting neurosecretory material from the brain, the pars intercerebralis, or the corpora cardiaca of
S. bullata
, or from the brain or c. cardiaca of
Periplaneta
or
Pyrrhocoris
into the posterior part induces it to tan before the anterior part. Injection of the same material into normal larvae after the critical period similarly accelerates puparium formation and onset of tanning. Injection of ecdysone or ecdysterone does not have these effects. Thus, the neurosecretory material does not act by causing the release of ecdysone from the ring gland and its function is different from that of the classical brain (“activating”) hormone. When injected before the critical period together with ecdysone it potentiates the effect of ecdysone. It is suggested that its biological significance is to coordinate puparial contraction and tanning.
HETEROGENEOUS CIRCULAR DNA ELEMENTS IN VEGETATIVE CULTURES OF
Bacillus megaterium
Authors: Carlton Bruce C. , Helinski Donald R.
Published: May 2006

DNA preparations from two strains of
Bacillus megaterium
, one which produces megacin and another that is megacin sensitive, were analyzed by dye-buoyant density centrifugation, cesium chloride gradient equilibrium centrifugation in the absence of dye, zone sedimentation in sucrose, and electron microscopy. Both strains were found to contain a substantial proportion of their total DNA as circular, covalently closed, double helical molecules. These DNA elements were heterogeneous in size and appeared slightly less dense than chromosomal DNA. The physiological role and origin of these elements is unknown at present.
PHOTOHYDRATION OF URIDINE IN THE RNA OF COLIPHAGE R17, I. REDUCTIVE ASSAY FOR URIDINE PHOTOHYDRATION
Authors: Cerutti P. A. , Miller N. , Pleiss M. G. , Remsen J. F. , Ramsay W. J.
Published: May 2006

Photohydration of uridine in the RNA of
E. coli
bacteriophage R17 has been investigated with the help of a new chemical method which avoids digestion of the irradiated polymer. The uridine photohydrates are reductively cleaved with sodium borotritiide and the radioactively labeled fragment, 1,3-propane-diol-
3
H
α
,
3
H
α
,
3
H
γ
, formed in this reaction is isolated and used as a measure for the extent of uridine photohydration in the irradiated RNA.

The influence of the conformational state of R17-RNA on the cross section of uridine photohydration (σ
H
) was investigated. The cross section for irradiation at 280 mμ at 25° was largest in 6
M
urea (σ
H
= 0.053), slightly smaller in low salt (<10
-3
M
Na
+
; σ
H
= 0.050), and substantially smaller in 0.15
M
Na
+
(σ
H
= 0.038). The closeness of the values for σ
H
in urea and low salt indicates that a majority of the uridine residues in R17-RNA in the low salt medium at 25° are not hydrogen bonded and destacked. The significant suppression of photohydration in 0.15
M
Na
+
on the other hand shows that a substantial portion of the uridine residues in R17-RNA are participating in base pairing and base stacking under these conditions. Our results demonstrate that studies of uridine photohydration may, beyond their importance to photobiology, yield information specifically about the conformational state of the uridine-rich regions of a RNA, information which cannot be readily obtained by other techniques.
PRE-FORK SYNTHESIS: A MODEL FOR DNA REPLICATION
Authors: Haskell Edwin H. , Davern Cedric I.
Published: May 2006

A model of DNA replication is presented in which DNA synthesis is continuously initiated from parental strand nicks and occurs, with conservation of helix winding number, ahead of the so-called replicating fork. The fork in this model is the locus of unwinding of already replicated, but presumably unstable, DNA. The model, involving Okazaki's notion of multiple initiation, is based upon the properties of Kornberg's DNA polymerase and accounts for the presence of single-stranded nascent DNA fragments in cell lysates. In addition to acting as sites of initiation, the parental strand nicks are implicated as sites of free rotation allowing unwinding of the replicated DNA.
THE ELECTION TRANSPORT SYSTEM IN NITROGEN FIXATION BY
Azotobacter
, I. AZOTOFLAVIN AS AN ELECTRON CARRIER
Authors: Benemann J. R. , Yoch D. C. , Valentine R. C. , Arnon D. I.
Published: May 2006

A flavoprotein, named azotoflavin, was isolated from an extract of
Azotobacter vinelandii
cells, which linked the reducing power generated by illuminated spinach chloroplasts to the
Azotobacter
nitrogen-fixing enzyme complex. The photoreduction of the yellow azotoflavin by chloroplasts produced a stable, free-radical semiquinone, blue in color, with properties similar to those described by other investigators for an
Azotobacter
flavoprotein of unknown biological function.
A PROTEIN INHIBITOR OF ACID DEOXYRIBONUCLEASES
Authors: Lesca Pierre , Paoletti Claude
Published: May 2006

A protein extracted and partially purified (about 100-fold) from mouse liver is able to inhibit the acid DNases from different tissues and species, whereas pancreatic DNase and
E. coli
endonuclease I are not inhibited. The acid DNase displays typical Michaelis-Menten kinetics in the absence of this inhibitor, but the kinetics become sigmoidal in its presence. The existence of a DNase-inhibitor complex is demonstrated by physicochemical experiments. Moreover, the inhibitor is able to reactivate the DNase treated by urea, probably through a reassociation of the inactive monomers to a dimeric state. An allosteric model in which the DNase-inhibitor complex is composed of catalytic (DNase) and regulatory (inhibitor) subunits could explain these data.
STUDIES OF THE AROMATIC CIRCULAR DICHROISM OF STAPHYLOCOCCAL NUCLEASE
Authors: Omenn Gilbert S. , Cuatrecasas Pedro , Anfinsen Christian B.
Published: May 2006

Specific contributions of tyrosyl and of tryptophanyl residues can be distinguished in the near-ultraviolet circular dichroic spectrum of staphylococcal nuclease. Upon binding of the inhibitor deoxythymidine 3′,5′-diphosphate in the presence of Ca
++
, a significant change in the circular dichroic spectrum results which has been used to characterize the interaction of ligand and enzyme. The data suggest that the asymmetric environment of certain tyrosyl residues is altered by binding of the nucleotide inhibitor.
THE UTILIZATION OF GENES FOR RIBOSOMAL RNA, 5
S
RNA, AND TRANSFER RNA IN LIVER CELLS OF ADULT RATS
Authors: Quincey R. V. , Wilson S. H.
Published: May 2006

The rates of synthesis of ribosomes, 5
S
RNA, and tRNA necessary to maintain the steady-state concentrations of these entities in liver cytoplasm of adult rats were determined. On the average, each liver cell in the adult rat synthesizes 650 ribosomes, 650 molecules of 5
S
RNA, and 11,000 molecules of tRNA each minute. The numbers of genes per liver cell for rRNA, 5
S
RNA, and tRNA were 330, 1660, and 13,000, respectively, as determined by RNA: DNA hybridization experiments. Thus, on the average, individual genes for rRNA, tRNA, and 5
S
RNA are transcribed twice a minute, once a minute, and once every 2.5 minutes, respectively, in the adult rat liver.
SUBGROUPS OF AMINO ACID SEQUENCES IN THE VARIABLE REGIONS OF IMMUNOGLOBULIN HEAVY CHAINS
Authors: Cunningham Bruce A. , Pflumm Mollie N. , User Urs Rutisha , Edelman Gerald M.
Published: May 2006

The amino acid sequence of the first 133 residues of the heavy (γ) chain from a human γG immunoglobulin (He) has been determined. This γ-chain is identical in Gm type to that of protein Eu, the complete sequence of which has been reported. Comparison of the two sequences substantiates the previous suggestion that there are subgroups of variable regions of heavy chains. The variable region of Eu has been assigned to subgroup I and that of He to subgroup II; on the other hand, the constant regions of the two proteins appear to be identical. Comparison of the sequence of the heavy chain of He with the heavy chain sequences determined in other laboratories suggests that the variable region of subgroup II is at least 118 residues long. The nature and distribution of amino acid variations in this heavy chain subgroup resemble those observed in light chain subgroups.

These studies provide evidence that the translocation hypothesis applies to heavy as well as to light chains, viz., genes for variable regions (
V
) are somatically translocated to genes for constant regions (
C
) to form complete
VC
structural genes.
TRANSCARBOXYLASE, VIII. ISOLATION AND PROPERTIES OF A BIOTIN-CARBOXYL CARRIER PROTEIN
Authors: Gerwin Brenda I. , Jacobson Birgit E. , Wood Harland G.
Published: May 2006

Methylmalonyl CoA-oxalacetate transcarboxylase (EC 2. 1. 3. 1) from
Propionibacterium shermanii
is a biotin enzyme of 670,000 molecular weight containing 6 moles of biotin per mole of enzyme. The active enzyme dissociates spontaneously at low ionic strength and alkaline pH to a mixture of inactive subunits. One type of subunit contains all the biotin of the original molecule. The biotin unit has an

S
20,w

= 1.3
S
and a molecular weight of approximately 12,000. It contains 1 mole of biotin and 1 half-cystine per mole. Qualitative dansyl techniques indicate that alanine is the amino terminal residue of the biotin subunit.
COMPLEMENTARY NUCLEAR RNA'S OF MURINE SARCOMA-LEUKEMIA VIRUS COMPLEX IN TRANSFORMED CELLS
Authors: Biswal Nilambar , Benyesh-Melnick Matilda
Published: May 2006

The high molecular weight RNA (
S

20,
w

= 69
S
) of murine sarcomaleukemia virus (MSV-MLV) complex dissociated into 37
S
subunits when heated to 95°C for 2 minutes. Specific annealing tests revealed that the viral RNA had complementarity with two heterogeneous RNA species from the nuclei of cells (78 A1) transformed by and chronically infected with this virus complex. The two nuclear RNA species that hybridized with the viral RNA had sedimentation constants ranging from 31-36
S
and 18-22
S
, respectively. There was no specific annealing between viral RNA and the cytoplasmic RNA of the 78 A1 cells. The detection of the complementary RNA strands of MSV-MLV suggests that this oncogenic virus complex may replicate in a fashion similar to that of the non-oncogenic RNA viruses, but may differ in that the complementary strands are found in the nucleus rather than in the cytoplasm of the transformed cells.
THE ELECTRON TRANSPORT SYSTEM IN NITROGEN FIXATION BY
Azotobacter
. II. ISOLATION AND FUNCTION OF A NEW TYPE OF FERREDOXIN
Authors: Yoch D. C. , Benemann J. R. , Valentine R. C. , Arnon Daniel I.
Published: May 2006

A new type of ferredoxin was isolated from
Azotobacter vinelandii
cells. The protein was able to replace the native chloroplast ferredoxin in the photoreduction of nicotinamide adenine dinucleotide phosphate (NADP) and functioned as a reductant for the
Azotobacter
nitrogenase.
Electron Spin Resonance Studies of Lipid-Protein Interaction in Human Serum Lipoproteins
Authors: Gotto A. M. , Kon H. , Birnbaumer M. E.
Published: May 2006

Spin-labeled derivatives of high density (HDL) and low density (LDL) lipoproteins from human serum were prepared with
N
-(1-oxyl-2,2,6,6-tetramethyl-4-piperidinyl)-maleimide. At the low ratios of spin label to protein employed, no changes in circular dichroism or immunochemical reactions were detected. The lipoprotein derivatives, labeled in their protein moieties, exhibited electron spin resonance spectra containing signals of strongly immobilized and weakly immobilized components. The strongly immobilized component was relatively more prominent in high density than in low density lipoproteins. Delipidation or addition of detergent greatly reduced the relative magnitude of the highly-immobilized signal. Reaction with specific antibodies did not alter the signals of spin-labeled lipoproteins or apoproteins. The signals of the reconstituted complex of spin-labeled apoHDL-phospholipid were indistinguishable from those of a spin-labeled apoHDL in the absence of lipid.
Hybridization of Native and Chemically Modified Enzymes, III. The Catalytic Subunits of Aspartate Transcarbamylase
Authors: Meighen E. A. , Pigiet V. , Schachman H. K.
Published: May 2006

Succinylation of the catalytic subunits of ATCase yielded a relatively homogeneous, inactive electrophoretic variant which upon mixing with native regulatory subunits formed a complex the size of the native enzyme. Hybridization experiments with mixtures of this variant and the native catalytic subunits in the presence of excess regulatory subunits yielded three different molecular complexes which were separated and individually characterized. The number and properties of the various components indicated that each ATCase molecule contains two catalytic subunits. Hybridization was also effected at the intrasubunit level by dissociation and reconstitution of mixtures of the native and modified catalytic subunits. These experiments produced four components showing thereby that each catalytic subunit is composed of three polypeptide chains. The potential use of the various hybrids is discussed in relation to the unique properties manifested by regulatory enzymes.
Phase Difference in the Induction of Tyrosine Hydroxylase in Cell Body and Nerve Terminals of Sympathetic Neurones
Authors: Thoenen Hans , Mueller Robert A. , Axelrod Julius
Published: May 2006

The induction of tyrosine hydroxylase in the nerve terminals of the rat heart by reserpine lags behind that in the stellate ganglion by two to three days. Cycloheximide given three days after reserpine blocks the further rise of the enzyme in the nerve terminals. The increase in tyrosine hydroxylase activity of the lumbar ganglion is as marked as that in the stellate ganglion. The increase of enzyme activity in the sciatic nerve after reserpine administration resembles that found in the heart nerve terminals. Determination of enzyme activity in segments of sciatic nerves indicates a two-day lag and then a proximal-distal transport of enzyme, but the apparent rate is not sufficient to account for the increase in enzyme in the nerve terminals. These findings are compatible with the local synthesis of induced tyrosine hydroxylase in the nerve terminals rather than the peripheral movement of the completed enzyme.
Immunoglobulin M: Pentameric Fcμ Fragments Released by Trypsin at Higher Temperatures
Authors: Plaut Andrew G. , Tomasi Thomas B.
Published: May 2006

Immunoglobulin M (IgM, 19
S
macroglobulin) is a high molecular weight antibody molecule currently thought to be composed of five identical 7
S
subunits linked by disulfide bonds, perhaps in a cyclic conformation. Reported molecular weights of IgM vary from 8 × 10
5
to 10
6
. Proteolytic cleavage of this molecule under standard conditions with several enzymes results in the formation of ten antigen-binding (Fab) fragments per mole, each Fab having a molecular weight of 40,000. The remainder of the molecule, designated Fc by analogy with the structure of immunoglobulin G (IgG), is highly susceptible to further enzyme cleavage and breaks down to dialyzable peptides. However, under carefully controlled conditions, an intact Fc-like fragment in low yield can be isolated from short-term papain digests of IgM at 37°C. Availability of the Fc portion of the molecule is important not only for structural studies but because it may determine certain important biological properties of the molecule such as complement fixation and placental permeability.

We here report that trypsin cleavage of IgM at temperatures exceeding 50°C results in the production of excellent yields of an intact Fc fragment, whereas no detectable Fc fragment is produced by trypsin cleavage at 37°C. Fab fragments are obtained under both temperature conditions, and an Fab dimer has been identified in high temperature digests. This unusual difference in the products of enzyme digestion with temperature is unexplained but may be related to steric changes induced in the IgM molecule by heat. Fc fragment isolated from high temperature digests contains two-thirds of the carbohydrate of the intact molecule, and has a molecular weight of 342,000. The molecular weight falls to 67,300 after treatment with disulfide reducing agents, thus supporting the concept of a pentameric structure for IgM.
Ribosomal RNA Homologies among Distantly Related Organisms
Authors: Bendich Arnold J. , McCarthy Brian J.
Published: May 2006

The similarity in base sequences of ribosomal RNA (rRNA) in widely divergent organisms was compared. Hybrids were prepared between
Escherichia coli
and pea rRNA on the one hand and the DNA of several organisms on the other. The varying thermal stabilities of these hybrids were taken as evidence for a hierarchy of rRNA relatedness among some higher plants, and for phylogenetic relationships among some species of bacteria, protozoa, fungi, plants, and animals. The large rRNA molecule appears to have evolved faster than the small rRNA molecule.
Peptide Chain Termination, VI. Purification and Site of Action of
S
Authors: Goldstein J. , Milman G. , Scolnick E. , Caskey T.
Published: May 2006

Peptide chain termination is a result of at least two events: terminator codon recognition and hydrolysis of peptidyl tRNA. A protein factor
S
, isolated from the supernatant of
Escherichia coli
B, stimulates fMet release. Factor
S
lowers the

K
m

for terminator trinucleotides without altering the
V
max
of release and therefore acts at terminator codon recognition. The
S
protein differs from initiation factors, elongation factor
G
, several forms of elongation factor
T
and release factors. The importance of the 2%
Tu
content in purified
S
is unresolved.
A Muscarone-Binding Material in Electroplax and Its Relation to the Acetylcholine Receptor, II. Dialysis Assay
Authors: O'Brien R. D. , Gilmour L. P. , Eldefrawi M. E.
Published: May 2006

An equilibrium dialysis technique, applied to lyophilized particulate fractions of
Torpedo
electroplax, gave data consistent with a single kind of macromolecular binding of muscarone, with binding constant, 7 × 10
-7
M
and an amount of 1 nmole per gram original electroplax. The effects on muscarone binding of 38 drugs suggested that muscarone binding reflected acetylcholine receptor activity. Of 18 enzyme preparations, only trypsin, chymotrypsin, and phospholipase C reduced binding activity, suggesting that a phospholipoprotein was binding. Partial „solubilization” of the binding protein was achieved, but the „solubilized” activity did not migrate on electrophoresis. Additional evidence was provided that acetylcholinesterase was not responsible for this muscarone binding.
Neutralization of Sensitized Virus by Purified Components of Complement
Authors: Daniels Charles A. , Borsos Tibor , Rapp Herbert J. , Snyderman Ralph , Notkins Abner Louis
Published: May 2006

Herpes simplex virus which had been sensitized with immunoglobulin M antibody was neutralized by serum deficient in the fifth and sixth components of complement (C) but not by serum deficient in the fourth component C (C4). The sequential addition of the functionally purified components of C showed that the activated first component of C (C1[unk]) failed to neutralize sensitized virus. However, in the presence of an optimal concentration of C1[unk], the addition of C4 resulted in neutralization. The amount of virus neutralized was dependent upon the concentration of immunoglobulin M used to sensitize the virus and the concentration of C1[unk] and C4. The addition of the second component of C (C2) to reaction mixtures containing an optimal concentration of C1[unk] and a limiting concentration of C4 resulted in increased neutralization and the amount of virus neutralized was dependent upon the concentration of C2. The addition of the third component of C (C3) to reaction mixtures containing an optimal concentration of C1[unk] and limiting concentrations of C4 and C2 also resulted in increased neutralization and the amount of virus neutralized was dependent upon the concentration of C3.
Peptide Chain Termination, VII. The Ribosomal and Release Factor Requirements for Peptide Release
Authors: Tompkins R. K. , Scolnick E. M. , Caskey C. T.
Published: May 2006

Release factors participate in release of fMet from fMet-tRNA · AUG · ribosome intermediates upon binding to ribosomes. This release requires R factor and occurs in the absence of terminator codon in reactions containing 20 per cent ethanol. Release occurs only when both 30
S
and 50
S
ribosomal subunits are present and when fMet-tRNA is located in the ribosomal P site. Release factor-dependent deacylation of fMet-tRNA is inhibited by sparsomycin, amicetin, lincocin, and chloramphenicol, antibiotics which have little effect on binding of R factor to ribosomes. The possible role of peptidyl transferase in the release reaction is discussed.
Control of Nitrate Reductase Activity in Barley Aleurone Layers
Authors: Ferrari T. E. , Varner J. E.
Published: May 2006

Nitrate reductase activity in barley (
Hordeum vulgare
L. cv. Himalaya) aleurone layers has been determined in the intact tissue, using two different methods. The first method measures the rate of appearance of H
2
18
O produced during the reduction of KN
18
O
3
. The second assay measures excreted nitrite resulting from nitrate reduction under anaerobic conditions. Nitrite production in this anaerobic, intact-tissue assay was dependent upon the presence of phosphate (pH 7.5) and was increased by ethanol and bisulfite.

After ten hours of nitrate induction, nitrate reductase activities measured by the KN
18
O
3
assay are one-sixth, and those measured by the anaerobic intact-tissue assay are one-third, of those observed in cell-free extracts of aleurone layers. Addition of ethanol to the anaerobic intact-tissue medium increased the rate of nitrate reduction to a level greater than that found in the cell-free assay.

Oxygen inhibited nitrite release in the anaerobic intact-tissue assay. However, under aerobic conditions and in the presence of 2-heptyl-4-hydroxyquinoline-
N
-oxide or antimycin A, nitrate reduction increased to rates comparable to those observed under anaerobiosis. Neither of these electron transport inhibitors affected anaerobic nitrate reduction, though they were effective in inhibiting oxygen uptake in separate experiments.
Secondary Structures of DNA
Authors: Wilkins M. H. F. , Wilson H. R. , Hamilton L. D.
Published: May 2006

The X-ray diffraction patterns of DNA do not support a four-stranded helical structure.
Ontogeny of Iminoglycine Transport in Mammalian Kidney
Authors: Baerlocher Kurt E. , Scriver Charles R. , Mohyuddin Fazl
Published: May 2006

Renal tubular absorption of proline, hydroxyproline, and glycine by the newborn of most mammals is inefficient compared to that of the adult. Cortex slices from seven-day-old rat kidney also transport proline and glycine at reduced initial rates compared to mature kidney. Nonetheless, newborn slices achieve higher intracellular concentrations during prolonged incubation; the latter reflects a reduced rate of efflux, a characteristic peculiar to the membrane of postnatal kidney. The postnatal reduction of initial uptake rates is observed clearly only at substrate concentrations in or below the physiological range; it correlates with the absence of two high-affinity systems which normally serve proline and glycine transport independently at these concentrations in mature kidney, in conjunction with a „common” low-affinity system. The low-affinity system alone performs the observed uptake in the newborn kidney. Specific activity of the high-affinity systems for proline and glycine increases asynchronously after birth, suggesting independent genetic control of the three systems for iminoglycine transport in mammalian kidney.
On the Prevalence of „Nonspecific” Binding at the Specific Binding Sites of Globular Proteins
Authors: Glazer A. N.
Published: May 2006

Strong binding of dyes to simple globular proteins takes place predominantly in areas overlapping the binding sites for substrates, coenzymes and prosthetic groups, in preference to other regions of the protein surface. The structure of the dyes bears no obvious relationship to that of the normal ligands. It is proposed that this phenomenon is a reflection of the special stereochemical features of such sites, their hydrophobicity relative to other portions of the protein surface, and, possibly, greater flexibility in these regions of the protein molecule. The binding properties of antibodies and bovine serum albumin are discussed in relation to this apparent versatility of protein binding sites towards structurally unrelated organic ligands.
Formation of All Stable RNA Species in
Escherichia coli
by Posttranscriptional Modification
Authors: Pace B. , Peterson R. L. , Pace N. R.
Published: May 2006

The kinetics of accumulation of the known stable RNA species (23
S
, 16
S
, and 5
S
rRNA and tRNA) in
Escherichia coli
C122 were monitored by polyacrylamide gel electrophoresis of purified cellular RNA, following termination of brief pulse labeling with
32
P-orthophosphate. Isotopically labeled stable RNA species appear only after a time lag, while total cellular RNA and the ostensible precursors to the stable RNA classes accumulate from the earliest times examined. It is concluded that all the known stable RNA species in
E. coli
are the products of posttranscriptional modification.
Proton Magnetic Resonance Study of Ferredoxin from
Clostridium pasteurianum
Authors: Poe M. , Phillips W. D. , McDonald C. C. , Lovenberg W.
Published: May 2006

Magnetic susceptibilities of both reduced and oxidized ferredoxin from
Clostridium pasteurianum
were obtained in solution. Whereas the reduced form exhibits a Curie law behavior, the magnetic susceptibility of oxidized ferredoxin in fact increases with temperature and suggests extensive antiferromagnetic exchange coupling between the component iron atoms. Contact-shifted resonances are observed for both forms of ferredoxin that are attributed to the β-CH
2
protons of the eight cysteine residues. A model based on these results is presented.
Proteins Specified by Herpes Simplex Virus, III. Viruses Differing in Their Effects on the Social Behavior of Infected Cells Specify Different Membrane Glycoproteins
Authors: Keller John M. , Spear Patricia G. , Roizman Bernard
Published: May 2006

We examined the electrophoretic properties of the proteins and glycoproteins in the smooth membranes and virions purified from cells infected with herpes simplex virus strains differing with respect to their effects on the interaction of cells among themselves. The data show the following: (1) The glycoproteins in virions and binding to membranes share common features but vary quantitatively and qualitatively depending on the virus strain. (2) The binding to smooth membranes is ordered and not random. (3) Differences in the glycosylation of membrane proteins in African green monkey (VERO) and human (HEp-2) cells indicate that glycosylation is at least in part determined by the host.
Transcription Initiation in the Histidine Operon of
Salmonella typhimurium
Authors: Atkins John F. , Loper John C.
Published: May 2006

Evidence is presented for two natural transcription initiators positioned internally in the histidine operon of
Salmonella typhimurium
. They were detected using highly polar
S. typhimurium his
mutants as recipients for F′
Escherichia coli his
episomes. These intergeneric complementation tests provide a sensitive method for the detection of other initiators and of terminators.

That at least part of the operator for the
his
operon lies distal to the transcription initiator is suggested by transduction analysis of a new highly polar mutant described in this paper.
Dolichol Monophosphate Glucose: An Intermediate in Glucose Transfer in Liver
Authors: Behrens Nicolás H. , Leloir Luis F.
Published: May 2006

The microsomal fraction of liver has been found to catalyze glucose transfer from UDPG to a lipid acceptor which appears to be identical to the compound obtained by chemical phosphorylation of dolichol. The substance formed (dolichol monophosphate glucose) is acid labile and yields 1,6-anhydroglucosan by alkaline treatment. It can be used as substrate by the enzyme system yielding a glucoprotein which is subsequently hydrolyzed to glucose.
Regulation of Axon Formation by Clonal Lines of a Neural Tumor
Authors: Seeds N. W. , Gilman A. G. , Amano T. , Nirenberg M. W.
Published: May 2006

Clonal lines of neuroblastoma cells were found to extend or retract axons depending upon the concentration of serum. Neurite extension was not inhibited by cycloheximide but was sensitive to colchicine or vinblastine, suggesting that neurite formation is dependent upon the assembly of microtubules or neurofilaments from preformed protein subunits.
Release of tRNA from Ribosomes by a Factor Other Than G Factor
Authors: Ishitsuka Hideo , Kaji Akira
Published: May 2006

In addition to the G factor there exists another factor in the
E. coli
extracts which stimulates the release of tRNA from ribosomes. This factor is distinctly different from the G factor and may play a role in removing tRNA from the ribosome after the polypeptide chain termination factor has released the completed chain from the ribosome-bound tRNA.
Neurogenesis and Morphogenesis in the Cerebellar Cortex
Authors: Eccles J. C.
Published: May 2006

The cerebellum presents the best site in the central nervous system for defining fundamental problems concerning the origin and differentiation of neurones, and their growth and development. The many recent experimental investigations of these problems are reviewed, and hypotheses based upon them are developed in relation to neurogenesis, morphogenesis, and synaptogenesis.
Synchronous Reinitiation of Chromosome Replication in
E. coli
B/r after Nalidixic Acid Treatment
Authors: Ward C. B. , Hane M. W. , Glaser D. A.
Published: May 2006

Nalidixic acid has been used to interrupt DNA synthesis in exponentially growing cultures of
E. coli
B/r. Within three minutes after removal of the nalidixic acid block, premature rounds of chromosome replication are initiated at the normal origin of vegetative DNA synthesis. The new growing forks traverse the chromosome in about 40 minutes, the normal replication time. These rounds continue synchronously into the second generation after removal of the nalidixic acid. These phenomena are similar in some respect to the premature initiation of chromosomal replication observed after thymine starvation or after release of thermo-sensitive DNA synthesis mutants from the restrictive temperature that prevents DNA synthesis.