bluuebunny/crossref_metadata_2025 huggingface dataset:
INHIBITION OF HERPES SIMPLEX VIRUS BY SYNTHETIC DOUBLE-STRANDED RNA (POLYRIBOADENYLIC AND POLYRIBOURIDYLIC ACIDS AND POLYRIBOINOSINIC AND POLYRIBOCYTIDYLIC ACIDS)
Authors: Hamilton L. D. , Babcock Virginia I. , Southam C. M.
Published: May 2006

Two-stranded polyriboadenylic and polyribouridylic acids and polyriboinosinic and polyribocytidylic acids protect against herpes simplex virus-induced cytopathogenicity in HEp 2 cultures, systemic herpes simplex virus infection in mice, and herpes simplex virus-induced keratoconjunctivitis in rabbits.
ACTIVATION OF RABBIT LIVER FRUCTOSE DIPHOSPHATASE BY COENZYME A AND ACYL CARRIER PROTEIN
Authors: Nakashima K. , Pontremoli S. , Horecker B. L.
Published: May 2006

The catalytic activity of rabbit liver fructose diphosphatase is enhanced more than fourfold by treatment with coenzyme A or acyl carrier protein. Other sulfhydryl compounds, such as glutathione or cysteine, are without effect. Activation is reversed by reduced glutathione or cysteine, indicating that the enzyme and activator are linked by disulfide bridges. The activated enzyme derivative can be formed by a disulfide exchange reaction at alkaline pH or by an oxidation reaction which proceeds at neutral pH. The latter process requires O
2
and Cu
++
, and is inhibited by EDTA.
STUDY OF CARBONIC ANHYDRASE USING PERTURBED ANGULAR CORRELATIONS OF GAMMA RADIATION
Authors: Meares Claude F. , Bryant Robert G. , Baldeschwieler John D. , Shirley David A.
Published: May 2006

The angular correlation of the 150-247 kev gamma-ray cascade of
111m
Cd is strongly perturbed when this nucleus is bound to the enzyme carbonic anhydrase. A comparison of the perturbed angular correlation for the apoenzyme with that for native carbonic anhydrase confirms that the
111m
Cd binds at the active region of the enzyme. These results provide good evidence that the perturbed angular correlation reflects the effective molecular rotational correlation time at the metal binding site, and that this radioactive nucleus can be used as a rotational tracer to label biological macromolecules. The qualitative dependence of the perturbed angular correlation of the
111m
Cd cascade on the molecular rotational correlation time at the metal binding site is illustrated using a cadmium-complex solution at various temperatures.
PATTERNS OF RNA SYNTHESIS IN T5-INFECTED CELLS I. AS STUDIED BY THE TECHNIQUE OF DNA-RNA HYBRIDIZATION-COMPETITION
Authors: Moyer Richard W. , Buchanan John M.
Published: May 2006

The RNA-labeling patterns obtained after T5 infection of
Escherichia coli
F agree with the patterns of protein labeling published by McCorquodale and Buchanan.
1
Three distinct classes of RNA formed sequentially during the period of viral development can be recognized by the DNA-RNA hybridization-competition technique. Class I RNA is formed within 5 minutes after the beginning of viral metabolism and corresponds to the RNA synthesized in response to infection with the 8 per cent segment of T5 DNA. Protein synthesis directed by this 8 per cent segment is required in some capacity for the cessation of class I synthesis and the beginning of the synthesis of class II at 4 to 5 min after infection. Class III RNA synthesis begins between 9 and 12 minutes. Its appearance is prevented when chloramphenicol is added immediately after complete expression of class I functions.
THERMODYNAMIC PARAMETERS FOR DISSOLVED GASES
Authors: Hildebrand Joel H.
Published: May 2006

In 1958 and subsequently we correlated properties of solutions of gases in liquids by using the “force constants,” ε/
k
, and collision diameters, σ, which serve as parameters in equations for molecular pair potential energy such as that of Lennard-Jones or its variants. Unfortunately, however, the figures for these parameters that have been published are so scattered for the same gas as to make it difficult to select “best” values; in 1967, therefore, I substituted for these indirectly determined molecular parameters the directly and accurately known molal energy of vaporization, ΔE
b
v
, and the molal volume, v
b
, of the liquefied gas, both at its boiling point. A plot of values of ΔE
2
v
against the most trustworthy values of ε/
k
reveals direct proportionality. The same is true for V
b
1/3
versus σ.

Recent examples will be shown of excellent linear correlations with these parameters of thermodynamic properties of different gases in the same solvent.

It is no less “scientific” and far more practical to regard molecules of a solute as immersed in the potential energy field of its solvent than it is to split this field into imperfectly known pair potentials of questionable additivity and to try to integrate them over an undetermined distribution function.
COMPARISON OF SOLUBLE HUMAN AND MOUSE TRANSPLANTATION ANTIGENS
Authors: Mann Dean L. , Nathenson Stanley G.
Published: May 2006

The molecular and chemical characteristics of membrane components bearing the major transplantation antigen systems in mouse (H-2) and man (HL-A) were compared and found to be strikingly similar.

Kinetics of papain solubilization from cell membranes, gel filtration, and electrophoretic patterns of the alloantigenic components were found to be nearly identical. Comparable size heterogeneity of the solubilized materials was also demonstrated. Some differences in amino acid and carbohydrate content of the purified H-2 and HL-A alloantigenic materials were found. The general pattern of distribution of the amino acid residues, however, appears to be quite similar and indicate compositional relatedness in these materials.

These physical and chemical similarities in the characteristics of molecules bearing the transplantation antigens are in accord with biologic studies indicating a comparable functional immunologic role for the mouse H-2 and human HL-A antigen systems. These studies support the view that the genes determining these major transplantation antigen systems may have evolved from a common precursor.
Phytochrome-Mediated Repression of Enzyme Synthesis (Lipoxygenase): A Threshold Phenomenon
Authors: Karow H. Oelze- , Schopfer P. , Mohr H.
Published: May 2006

Synthesis of the enzyme lipoxygenase in the cotyledons of the mustard seedling (
Sinapis alba L.
) is controlled by phytochrome (

P
fr

) through a threshold mechanism. The repression of enzyme synthesis by

P
fr

is a very rapid process after the threshold level is surpassed. Similarly, enzyme synthesis starts instantaneously and with full speed as soon as the

P
fr

level decreases below the threshold level. Thus

P
fr

rapidly inhibits synthesis of an enzyme and functions through an all-or-none control mechanism of high precision.
Genetic Mapping of Antibiotic Resistance in Markers
Bacillus subtilis
Authors: Goldthwaite C. , Dubnau D. , Smith I.
Published: May 2006

Several antibiotic resistance markers in
Bacillus subtilis
have been mapped by three-factor transduction crosses using bacteriophage PBS1. These markers, which are thought to be located in genes coding for ribosomal proteins, are within a segment comprising about 5 per cent of the
B. subtilis
genetic map, close to the major group of rRNA cistrons. The order of genetic makers in this region was found to be
cysA14 mic-1
†
str-1
(
ery-1, ole-2
)
spc-2 bry-2 lin-2
. The positions of
neo-2, nea-1
, and
kan-2
are uncertain, although they are located in this region to the right of
cysA14
.
Instrumental Conditioning of the Rat Cardiac Control Systems
Authors: Fields Craig
Published: May 2006

The PR, PP, and RR intervals of the rat EKG were instrumentally conditioned using a variety of reinforcement schedules under computer control. The PR and PP intervals could be conditioned independently. Individual rats demonstrated either a steady shift of their response distribution or an abrupt change of an all-or-none variety. Some response distributions shifted continuously; others, through the growth of new response patterns in a manner reminiscent of hypothesis-testing behavior of human subjects. A study of the effects of single reinforcements showed that each reinforcement contributed to the learning behavior of the subject, in a well-defined but nonlinear fashion.
Hamster-Tropic Sarcomagenic and Nonsarcomagenic Viruses Derived from Hamster Tumors Induced by the Gross Pseudotype of Moloney Sarcoma Virus
Authors: Kelloff Gary , Huebner Robert J. , Lee Yong Ki , Toni Robert , Gilden Raymond
Published: May 2006

Hamster sarcomas induced by the Gross pseudotype of Moloney sarcoma virus yielded a virus sarcomagenic for hamsters but not mice. This virus was able to produce foci on hamster embryo cells, but not on mouse embryo cells. A hamster-tropic nonfocus-forming helper virus was also found in the viral stocks. These hamster-tropic viruses are not immunologically related to the murine viruses in the original inoculum but appear to represent indigenous C-type RNA viruses of the hamster.
Nuclear Magnetic Resonance Studies of the Structure and Binding Sites of Enzymes, XI. Characterization of Selectively Deuterated Analogs of Staphylococcal Nuclease
Authors: Putter I. , Markley J. L. , Jardetzky O.
Published: May 2006

The preparation of five different selectively deuterated analogs of the enzyme staphylococcal nuclease has been previously reported.
1-3
The five selectively deuterated enzymes have full enzymatic activity with DNA and RNA substrates and identical amino acid compositions; and they all appear to have similar conformations in solution, despite their very different hydrogen/deuterium contents.
Electrical Activity in the Spinal Cord of the Chick Embryo,
in situ
Authors: Provine R. R. , Sharma S. C. , Sandel T. T. , Hamburger V.
Published: May 2006

Unit electrical activity was recorded from single neurons in the lumbo-sacral spinal cord of 15-, 17-, and 19-day chick embryos,
in situ
. The dorsal columns showed relatively continuous single-unit activity. Below this lies an area of relative quiet 100-200μ deep. The ventral two thirds of the cord was the most active region, being characterized by polyneuronal bursts and intermittently active single units.
On the Interactions of Lipids and Proteins in the Red Blood Cell Membrane
Authors: Glaser Michael , Simpkins Henry , Singer S. J. , Sheetz Michael , Chan Sunney I.
Published: May 2006

The effects of temperature and of the action of a purified phospholipase C enzyme preparation on human red blood cell membranes has been investigated by chemical analyses, circular dichroism, and proton magnetic resonance measurements. The results indicate that a substantial fraction of the phospholipids and the proteins of the membranes can change structure independently of one another, suggesting a mosaic pattern for the organization of the lipids and proteins in membranes.
Biotin-Bound CO
2
and the Mechanism of Enzymatic Carboxylation Reactions
Authors: Bruice Thomas C. , Hegarty A. F.
Published: May 2006

Considerations are provided which show that the carboxylation site (oxygen or nitrogen) of biotin is most likely unknown. Kinetic studies of intramolecular reactions of the ureido function at acyl carbon demonstrate that ureido oxygen attack is the preferred mode when the acyl group is activated. Transfer from the
O
-acylisourea formed by this route (relative to an
N
-acylurea) is also favorable. These model studies are related to the carboxylation and CO
2
transfer steps of biotin-mediated reactions, and a mechanism consistent with these results is postulated.
Differential Scatter of Left and Right Circularlay Polarized Light by Optically Active Particulate Systems
Authors: Urry D. W. , Krivacic J.
Published: May 2006

Because of the many heterogeneous systems which are of interest to the chemist and biochemist, the problems of distortions in circular dichroism patterns have been investigated. Specifically in this communication it is shown with a relatively well-characterized particular system (a suspension of α-helical poly-L-glutamic acid) that there is a measurable differential scatter of left and right circularly polarized light by suspensions of the optically active particles. This is a specific example of Perrin's assertion in 1942 (Perrin, F.,
J. Chem. Phys
., 10, 415 (1942)) that the polarization characteristics of scattered light would differ depending on whether or not the scattering particle was optically active.

Differential scatter is included with the concentration obscuring effects to demonstrate that distorted circular dichroism spectra on poly-L-glutamic acid suspension can be calculated with satisfying accuracy. The approach should be applicable to correcting the circular dichroism spectra for the many particles of biological interest, e.g., membranes, viruses, mitochondria, and insoluble proteins and polypeptides, and for small crystals in an effort to answer the crystal solution problem.
Pulse Labeling of RNA of Mammalian Cells
Authors: Rovera Giovanni , Berman Stephen , Baserga Renato
Published: May 2006

When cells from a hypotetraploid strain of Ehrlich ascites tumor are exposed to uridine-
3
H either
in vivo
or
in vitro
, the amount of radioactivity incorporated into RNA reaches a maximum within ten minutes, after which any further incorporation stops.
3
H-uridine triphosphate disappears from the acid soluble pool within 30 minutes and the findings indicate that the RNA of these cells can be pulse labeled without the use of any antibiotic or the need of a „chase.” The stability of the pulse labeled RNA in the presence of pentobarbital (an inhibitor of RNA synthesis) indicates the virtual absence of RNA breakdown. However, actinomycin D, at a dosage of 250 μg/mouse
in vivo
and 10 μg/ml
in vitro
produces breakdown of labeled RNA, thus confirming earlier observations that the drug is not a suitable tool for RNA kinetics determinations. The pulse-labeled RNA leaves the nucleus slowly and some radioactive RNA is still present in the nuclear fraction after 24 hours. Radioactivity begins to appear in cytoplasmic ribosomal RNA after 20 minutes and continues to increase up to six hours.
Topological and Functional Organization of the Mitochondrion
Authors: Smoly Jennie M. , Kuylenstierna Bo , Ernster Lars
Published: May 2006

The morphological and biochemical properties of isolated mitochondrial inner and outer membranes are summarized and discussed in relation to the functional organization of the intact mitochondrion. The enzymatic composition of the mitochondrial inner compartment is compared to over-all mitochondrial function. The role of the mitochondrial outer compartment is discussed with reference to both the inner membrane-matrix fraction and the intact mitochondrion.
Transcriptions of the Bacteriophage T4 Template
in Vitro:
Separation of „Delayed Early” from „Immediate Early” Transcription
Authors: Milanesi Gabriele , Brody Edward N. , Grau Oscar , Geiduschek E. Peter
Published: May 2006

The synthesis of different early T4 transcripts by
E. coli
RNA polymerase
in vitro
can be dissociated in two ways: (1) when T4 DNA is mechanically degraded, it selectively loses the ability to serve as a template for the transcription of
delayed early
T4 RNA; (2) when initiation of RNA synthesis on intact T4 DNA is limited to a very short time interval
immediate early
T4 RNA is synthesized at once but
delayed early
polynucleotide sequences appear only after a time lag. We conclude that initiation sites for T4 early RNA synthesis are closer to
immediate early
than to
delayed early
segments of the T4 template and that
immediate early
and
delayed early
segments of the T4 chromosome are interspersed. We propose that this interspersing is significant for the programming of transcription during T4 development.
Synthesis of Immunoglobulin Heavy and Light Chains by the Free Ribosomes of a Mouse Plasma Cell Tumor
Authors: Lisowska-Bernstein B. , Lamm M. E. , Vassalli P.
Published: May 2006

Free and membrane-bound ribosomes have been isolated from a mouse plasma cell tumor secreting immunoglobulins, and allowed to synthesize proteins under cell-free conditions. Analysis of the products of synthesis by autoradiography of immunoelectrophoresis and peptide maps indicates that both types of ribosomes synthesize heavy and light immunoglobulin chains.
A Source for the Special Catalytic Power of Enzymes: Orbital Steering
Authors: Storm Dan R. , Koshland D. E.
Published: May 2006

The velocities of acid catalyzed esterification and γ-lactonizations were studied to test the sensitivity of a chemical reaction to the orientation of the reacting atoms. Variation in orientation of the attacking oxygen atom relative to the carbon atom of the carboxylic acid was achieved by using bicyclic ring systems to limit the conformational mobility of the γ-hydroxy acids. Factors as high as 2 × 10
4
were observed for the acceleration of a reaction due to this „orientation factor” even after corrections for proximity and torsional strain have been made. The orientation factor is related to the shape of the electron orbitals and must have an angular preference far greater than previously estimated. Such sensitivity to orientation would provide factors large enough to explain the gap in our understanding of enzyme catalysis. It is suggested that the catalytic efficiency of enzymes depends on their ability not only to juxtapose the reacting atoms but also to „steer” their orbitals along a path which takes advantage of this strong directional preference.
In Vitro
Assembly of
Neurospora
Assimilatory Nitrate Reductase from Protein Subunits of a
Neurospora
Mutant and the Xanthine Oxidizing or Aldehyde Oxidase Systems of Higher Animals
Authors: Ketchum Paul A. , Cambier Helene Y. , Frazier William A. , Madansky Charles H. , Nason Alvin
Published: May 2006

In vitro
assembly or complementation of a hybrid assimilatory nitrate reductase was attained by mixing a preparation of nitrate-induced
N. crassa
mutant
nit-1
specifically with acid-treated (pH 2.5) bovine milk or intestinal xanthine oxidase, rabbit liver aldehyde oxidase, or chicken liver xanthine dehydrogenase. The complementation reaction specifically required induced
nit-1
, the only nitrate reductase mutant of
Neurospora
that lacked xanthine dehydrogenase and was unable to use hypoxathine or nitrate as a sole nitrogen source. The complementing activities of the above acid-treated enzymes correspond to their xanthine or aldehyde oxidizing activity profiles on sucrose density gradients. The resulting soluble, reduced nicotinamide adenine dinucleotide phosphate (NADPH)-nitrate reductases are the same as the
Neurospora
wild type enzyme in sucrose density gradient profile, molecular weight, substrate affinities, and sensitivity to inhibitors and temperature. By analogy to a similar
in vitro
complementation of nitrate reductase in mixtures of induced
nit-1
and individual nonalleic
Neurospora
mutants, or uninduced wild type, the complemented nitrate apparently consists of an inducible protein subunit (possessing inducible NADPH-cytochrome
c
reductase) furnished by
nit-1
and a subunit from the acid-treated xanthine or aldehyde oxidizing system which can substitute for the constitutive component furnished by the other mutants or uninduced wild type. The data suggest that
Neurospora
nitrate reductase and the xanthine oxidizing system and aldehyde oxidase of animals, all of which are molybdenum-containing enzymes catalyzing the reduction of nitrate to nitrite, share a highly similar protein subunit.
Early Recovery of Antidromic Conduction through Dendrites of Spinal Motoneurons in the Normal, Anoxic, and Postanoxic States
Authors: Lloyd David P. C.
Published: May 2006

Penetration of two closely (3.2 Msec) spaced antidromic volleys in dendrites of spinal motoneurons is considered in the normal, anoxic, and postanoxic states. It is concluded that the value of the L-fraction (Lorente de N6) of membrane potential at the time of impulse conduction largely determines the extent of penetration or, in other words, the spatial decrement of dendritic conduction. The observations are pertinent to interpretations with respect to monosynaptic reflex transmission.
Excitatory Postsynaptic Potential and Monosynaptic Reflex Discharge of Spinal Motoneurons during Anoxic Insult
Authors: Lloyd David P. C.
Published: May 2006

Almost universally held is the concept that in transmission from one neuron to another the so-called postsynaptic potential is the essential step leading to discharge of the secondary neurons. According to the present experiments this is not so in the monosynaptic reflex system of the cat spinal cord. Its role in facilitation of response and certain other essential data are mentioned.
Initiation and Release of RNA by DNA-Dependent RNA Polymerase
Authors: Millette Robert L. , Trotter Carol D.
Published: May 2006

During
in vitro
transcription of T4 DNA by
E. coli
RNA polymerase, chain initiation stops coincidentally with synthesis at low ionic strength (0.11) with an average of one RNA chain initiated per 24S polymerase molecule. At high ionic strength (0.37), initiation as well as synthesis continues for several hours, with an average of four chains initiated per enzyme molecule in two hours. The RNA product is released from the T4 DNA template at both low and high ionic strength. At high ionic strength, however, RNA polymerase can repeatedly initiate, synthesize, and release RNA from the synthesis complex
in vitro
. Under both conditions, the synthesized RNA sediments at 25-44 S, has a number average chain length of 5000 to 7500 nucleotides, and a weight average chain length of 11,500 nucleotides.
Isozyme Patterns and Sexual Morphogenesis in
Schizophyllum
Authors: Wang Chiu-Sheng , Raper John R.
Published: May 2006

Isozymes of several different classes of enzymes in partially purified protein extracts of five strains of
Schizophyllum commune
, isogenic except for genes controlling sexual morphogenesis, were separated on polyacrylamide gel by disc electrophoresis. After staining, isozyme patterns were compared on the bases of the presence or absence, electrophoretic mobility (
R

f

values), and relative activities of specific isozymes. Differences in isozyme patterns in 14 enzymes, i.e., NADH-dehydrogenase, NADPH-dehydrogenase, a number of NAD and NADP-dependent dehydrogenases, acid phosphatases, leucine aminopeptidase, and esterases, were correlated with the operation or inactivity of the
A
-and
B
-sequences of sexual morphogenesis. In only a single instance, i.e., phenolases, no marked differences could be correlated with sexual morphogenesis.
A Hummingbird-Pollinated Species of Boraginaceae in the Arizona Flora
Authors: Grant Verne , Grant Karen A.
Published: May 2006

Marcomeria viridiflora
(Boraginaceae) is pollinated by broad-tailed and rufous hummingbirds in the White Mountains of Arizona. This is the first hummingbird-pollinated member of the family Boraginaceae to be recorded in western North America. It provides one more example of a predominantly beepollinated plant group that has given rise to one or a few exceptional species of hummingbird flowers in western North America.
Partial Purification of the Ouabain-Binding Component and of Na,K-ATPase from Human Red Cell Membranes
Authors: Dunham Philip B. , Hoffman Joseph F.
Published: May 2006

Ghosts of human red cells were incubated with tritiated ouabain in the presence of ATP, Mg, and Na, conditions under which ouabain binds with high specificity to Na:K transport sites. The labeled membranes were solubilized with sodium dodecyl sulfate and dialyzed. Sodium dodecyl sulfate solubilizes most of the membrane protein and leaves most of the tritiated-ouabain bound to a solubilized component. Solubilized Na,K-ATPase could also be obtained after dialysis. The solubilized membranes were centrifuged in a sucrose density gradient. The ouabain-membrane complex and the Na,K-ATPase sedimented faster than the bulk of the protein. The ouabain-membrane complex and the Na,K-ATPase appeared to be identical and were purified about eightfold relative to the starting material. These results represent a step toward the isolation and characterization of the cation transport mechanism in red cell membranes.
INTERFERON AND CELL DIVISION, I. INHIBITION OF THE MULTIPLICATION OF MOUSE LEUKEMIA L 1210 CELLS
In Vitro
BY INTERFERON PREPARATIONS
Authors: Gresser Ion , Brouty-Boyé Danièle , Thomas Marie-Thérèse , Macieira-Coelho Alvaro
Published: May 2006

Mouse interferon preparations inhibited the multiplication of mouse leukemia L 1210 cells in stationary suspension cultures. The degree of inhibition was found to correlate with the antiviral titer of the interferon preparations. The factor(s) responsible for inhibition of L 1210 cell multiplication could not be dissociated from interferon by standard physicochemical means.
TRANSDUCTION BY BACTERIOPHAGE T1
Authors: Drexler Henry
Published: May 2006

Amber mutants of the virulent coliphage T1 are able to transduce a wide variety of genetic characteristics from permissive to nonpermissive K strains of
Escherichia coli
.
IMPEDANCE CHANGES ACROSS THE FOOTPAD OF THE CAT IN RELATION TO ACTION AND SECRETION IN SWEAT GLANDS
Authors: Lloyd David P. C.
Published: May 2006

Impedance changes across the footpad of the cat occur as the result of sweat gland activity after stimulation of the sudomotor nerves. It is possible to discern two phases of impedance change; one, early, associated with the action potential of sweat gland cells; the other, later, being the well-known change associated with secretion and reabsorption.
1
After a single stimulus, latency for the initial impedance change is about that of the sweat gland cell action potential, that of the secretory change approximately 1 additional second.
Genetic Transmission of Viruses That Incite Mammary Tumor in Mice
Authors: Bentvelzen P. , Daams J. H. , Hageman Philomena , Calafat Jero
Published: May 2006

Electron microscopy, immunofluorescence, and bioassay demonstrated the presence of a mammary tumor inciting virus in untreated mice of three different inbred strains, and in irradiated or urethan-treated mice of two other mouse strains, indicating the ubiquitous nature of this group of viruses. In general these viruses are transmitted vertically by the gametes of the mouse strain in which they naturally occur. The virus is present in every cell, although often in an incomplete form. If a mammary tumor inciting virus is introduced into a different mouse strain, only milkborne transmission will take place, after which the virus is found in a limited number of tissues.

It has been speculated that mammary tumor inciting viruses are transmitted as genetic factors of the host strain to which they belong. There is some evidence that a repressor, produced by a regulator gene, controls the rate of release of such a genetically transferred virus. Repression can be abrogated by a carcinogenic treatment. The repressor would also cause resistance to a superinfecting mammary tumor inciting virus by interference with its replication.
An Endonuclease Activity from
Escherichia coli
Absent from Certain
rec
-
Strains
Authors: Goldmark Peter J. , Linn Stuart
Published: May 2006

A new endonuclease activity from
Escherichia coli
which cleaves circular, single-stranded DNA in the presence of added nucleoside triphosphate has been purified. The activity has not been detected in extracts from certain
rec
-
strains and is therefore implicated in genetic recombination.
The Rolling Circle for ϕX DNA Replication, III. Synthesis of Supercoiled Duplex Rings
Authors: Dressler David , Wolfson John
Published: May 2006

During ϕX duplex ring synthesis, the first supercoils to acquire radioactivity after the addition of tritiated thymidine are labeled only in their negative strands. In longer pulses, this asymmetry of labeling progressively disappears. This finding supports the rolling circle model for DNA replication due to the structural asymmetry of its replicating intermediate, but is not predicted by the Cairns or Yoshikawa models.
Interactions of
p
-Nitrobenzene Diazonium Fluoroborate and Analogs with the Active Sites of Acetylcholine-Receptor and -Esterase
Authors: Mautner Henry G. , Bartels Eva
Published: May 2006

p
-Nitrobenzene diazonium fluoroborate (NDF) is a potent inhibitor of the carbamylcholine-induced depolarization of the electroplax and of acetylcholinesterase. It probably forms covalent bonds with the acetylcholine-receptor and -esterase at the active site of the proteins. Its inhibitory strength is at least the same as that of trimethylammonium diazonium fluoroborate (TDF). The
p
-acetoxy analog, with its weaker electron-withdrawing group, is about ten times weaker as an inhibitor than the trimethylammonium or
p
-nitro analogs, both of which have strong electron-withdrawing groups. After treatment of the electroplax preparation with dithiothreitol, NDF remains an irreversible receptor-inhibitor, while TDF becomes a potent reversible receptor-activator. TDF is self-inhibitory: applied before reduction, it no longer depolarizes.

Although the first observations on TDF suggested that the compound labels both proteins by virtue of the steric complementary of its trimethylammonium group to a negative subsite in the proteins, the present study indicates that it is the positively charged diazonium group that reacts with the active sites of the proteins to form a covalent bond with an appropriate amino-acid residue.
Reaction of Diethyl Pyrocarbonate with Nucleic Acid Components, I. Adenine
Authors: Leonard Nelson J. , McDonald Jerome J. , Reichmann M. E.
Published: May 2006

The use of diethyl pyrocarbonate as a nuclease inhibitor in the preparation of RNA of high molecular weight has prompted a study of the possible reactions of this compound with nucleic acid components under the conditions generally employed for providing inhibition. The first substrate investigated was adenine, which has been found to undergo ring opening with the formation of 5(4)-
N
-carbethoxyaminoimidazole-4(5)-
N
′- carbethoxycarboxamidine (II). This product was converted efficiently to isoguanine by treatment with ammonia. The structure of II was established by spectroscopy.

For comparisons of reactivity and of spectroscopic and chromatographic properties with the adenine-diethyl pyrocarbonate product, the compounds 9-carbethoxyadenine, 6-
N
-carbethoxyaminopurine (V), and 6-ethylaminopurine were made; compound V was made by employing the 1-ethoxyethyl protecting group in the synthetic sequence. Purine compounds can be converted to 9-(1-ethoxyethyl) derivatives simply by refluxing in acetal.

The facile reaction of adenine with diethyl pyrocarbonate illustrates the importance of gaining information as to the fate of various nucleic acid components in the presence of diethyl pyrocarbonate.
Optical Activity of Bovine Neurophysins and Their Peptide Complexes in the Near Ultraviolet
Authors: Breslow Esther
Published: May 2006

Circular dichroism studies of the bovine neurophysins in the near ultraviolet show a strong negative band at 280 nm and a strong positive band at 248 nm, both of which are attributable almost exclusively to disulfide transitions. The ellipticities per disulfide bond of the unresolved bands in neurophysin-II are -2900 deg cm
2
/decimole and +2300 deg cm
2
/decimole at 280 nm and 248 nm, respectively. Binding of oxytocin, vasopressin, or the peptide
S
-methyl-L-cysteinyl-L-tyrosyl-L-phenylalanine amide lead to large changes in optical activity in the near and far ultraviolet. Of these circular dichroism changes above 290 nm are attributed to changes in the optical activity of neurophysin disulfides, while changes elsewhere are more generally ascribed to changes in either disulfide, tyrosine, or peptide bond transitions. Optical rotatory dispersion studies show that calcium ion, at concentrations of 0.01 M, has only trivial effects on the affinity of bovine neurophysins for oxytocin.
DNA Replication in
Escherichia coli:
Location of Recently Incorporated Thymidine Withi Molecules of High Molecular Weight DNA
Authors: Iyer V. N. , Lark K. G.
Published: May 2006

More than 50% of the [
3
H]thymidine incorporated during short pulses into the DNA of
Escherichia coli
15T
-
can be extracted by alkali as high molecular weight DNA. Density gradient centrifugation and digestion with exonuclease I suggest that these large pieces of DNA are composed of newly synthesized DNA attached to pre-existing material at the 3′ end of the molecule.
A Specific Hepatic Transfer RNA for Phosphoserine
Authors: Mäenpää Pekka H. , Bernfield Merton R.
Published: May 2006

Radioactive
O
-phosphoryl-L-serine was detected after alkaline deacylation of rat and rooster liver [
3
H]seryl-tRNA acylated
in vitro
with homologous synthetases. Ribonuclease treatment of this tRNA yielded a compound with the properties of phosphoseryl-adenosine. Benzoylated DEAE-cellulose chromatography of seryl-tRNA yielded four distinct peaks, only one of which contained phosphoserine. A unique fraction for phosphoserine was also found on chromatography of nonacylated tRNA. In ribosome binding studies, this fraction responded very slightly with poly(U,C), but not with any of the known serine trinucleotide codons. Substantial incorporation of [
3
H]-serine into protein from this tRNA species was observed in an aminoacyl-tRNA dependent polysomal system derived from chick oviducts. No phosphoserine was found in
Escherichia coli
or yeast seryl-tRNA acylated with homologous enzymes, nor in
E. coli
seryl-tRNA acylated with liver synthetase. In the absence of tRNA, free phosphoserine was not formed in reaction mixtures, which suggests that phosphoseryl-tRNA arises by phosphorylation of the unique seryl-tRNA species. These results demonstrate a discrete tRNA
Ser
species in rat and rooster liver containing phosphoserine and suggest that this tRNA is involved in ribosomal polypeptide synthesis.
Ion Transport Underlying Metabolically Controlled Volume Changes of Isolated Mitochondria
Authors: Izzard S. , Tedeschi H.
Published: May 2006

An earlier study has indicated that the swelling of isolated mitochondria induced by inorganic phosphate (P
i
) can be accounted for largely or completely by the accumulation of ions. In the present study, a similar uptake was shown to be induced by a wider range of P
i
concentrations. Addition of ADP, KCN, or 2,4-dinitrophenol initiates a shrinkage which can be accounted for by the efflux of ions. The results are consistent with the explanations that (
a
) P
i
induces a transport of ions and a concomitant osmotic swelling, and (
b
) the addition of substances which compete or interfere with the energy available for transport results in ion efflux and a corresponding mitochondrial shrinkage. The results are not consistent with proposals that the changes in the light scattered by mitochondrial suspensions with alterations in metabolic states reflect a mechanochemical coupling phenomenon.
Bovine Liver Glutamate Dehydrogenase: Tentative Amino Acid Sequence; Identification of a Reactive Lysine; Nitration of a Specific Tyrosine and Loss of Allosteric Inhibition by Guanosine Triphosphate
Authors: Smith Emil L. , Landon Michael , Piszkiewicz Dennis , Brattin William J. , Langley Trevor J. , Melamed Mark D.
Published: May 2006

A tentative but almost complete amino acid sequence for the subunit peptide chain of bovine liver glutamate dehydrogenase indicates a minimal size of 506 residues with a molecular weight of 56,100, in accord with the physical size of the subunit of 55,900. Inactivation with pyridoxal 5′-phosphate, followed by reduction with sodium borohydride, has permitted identification of the essential lysine as residue 97. Nitration of tyrosine-412 is accompanied by loss of the allosteric inhibitory effect of guanosine triphosphate.

Comparison of the sequences of glutamate dehydrogenase and glyceraldehyde-3-phosphate dehydrogenase has indicated that only two 12-residue sequences are similar in the two enzymes; this sequence includes reactive lysine-97 of the former enzyme.
Temperature-Sensitive Mutations in
Drosophila Melanogaster
, IV. A Mutation Affecting Eye Facet Arrangement in a Polarized Manner
Authors: Foster Geoffrey G. , Suzuki David T.
Published: May 2006

Drosophila melanogaster
females heterozygous for the mutation
N
60g11
have wild type eyes when raised at 29°C but a disrupted arrangement of facets and extra bristles at 21°C. Shifts of cultures from one temperature to the other at different stages in development revealed that facet arrangement is altered by temperature during the third larval instar. The facet pattern is affected in a vertical wave that proceeds anteriorly from the posterior rim of the eye. The role of the Notch locus in development is briefly discussed.
Rate Acceleration by Stereopopulation Control: Models for Enzyme Action
Authors: Milstien Sheldon , Cohen Louis A.
Published: May 2006

As a result of alkyl substitution in both aromatic ring and side chain, the rate constant for acid-catalyzed lactonization of hydrocoumaric acid is increased by factors as high as 10
11
and, in comparison with the bimolecular esterification of phenol and acetic acid, by almost 10
16
. In the most favorable case studied, the half-life of the phenolic acid (imidazole buffer, pH 7, 30°C) is 6 sec, with 90% of the total rate being due to catalysis by the buffer species. The effect is attributed to a unique interlocking of methyl groups, which produces a severe conformational restriction of the side chain and increases greatly the population of the most productive conformer. This phenomenon is presented as a model for the conformational restraint imposed by an enzyme on its substrate. The magnitude of the effect suggests that the contribution of substrate „freezing” to total rate enhancement by an enzyme can be considerably greater than previously supposed and may in fact be sufficient to complete the justification for enzyme catalysis.
Breakdown by Streptomycin of Initiation Complexes Formed on Ribosomes of
Escherichia coli
Authors: Modolell Juan , Davis Bernard D.
Published: May 2006

Streptomycin induces breakdown of the completed 70S initiation complex on ribosomes of
Escherichia coli
, but it does not interfere with any step in the formation of the complex. Moreover, it does not appear to interact with the ribosome in any special way during initiation, since the kinetics of breakdown are the same whether streptomycin is added before formation of the initiation complex, or after its completion, or (as previously observed) after formation of a polypeptide. fMet-tRNA is released as such, without chain elongation; it is released from a puromycin-reactive („P”) site. Streptomycin thus appears to distort not only the A site of the ribosome (as suggested earlier) but also the P site.
A Genetic Marker in the Variable Region of Light Chains of Mouse Immunoglobulins
Authors: Edelman Gerald M. , Gottlieb Paul D.
Published: May 2006

A genetic variation was observed upon autoradiographic comparison of tryptic peptide maps of
14
C-labeled normal light chains from 17 different inbred strains of mice. The difference was found in strains AKR/J, C58/J, and RF/J. Chemical analyses showed that the differences were in a region of the amino acid sequence in the neighborhood of half-cystine I of the variable region of the light chain. Breeding experiments showed that the difference segregated in a classical Mendelian fashion.
Identification and Origin of Some Chloroplast Aminoacyl-tRNA Synthetases and tRNAs
Authors: Reger Bonnie J. , Fairfield S. A. , Epler J. L. , Barnett W. Edgar
Published: May 2006

Light-grown, wild type
Euglena gracilis
contains two aminoacyl-tRNA synthetases for both phenylalanine and isoleucine. Only one of the two synthetases for each amino acid is found in isolated chloroplasts, as are the light-induced phenylalanine and isoleucine tRNAs. In each case the light-induced chloroplast tRNAs can only be acylated by the chloroplast synthetases. The chloroplast isoleucyl-tRNA synthetase is light-inducible and cannot be detected in dark-grown cells or in cells of the bleached mutant W
3
BUL. The presence of the chloroplast phenylalanyl-tRNA synthetase in W
3
BUL, which contains no chloroplast DNA or structure, indicates that this chloroplast enzyme is synthesized in the cytoplasm and is coded by nuclear genes.
Anthranilate Synthase Enzyme System and Complementation in
Pseudomonas
Species
Authors: Queener S. F. , Gunsalus I. C.
Published: May 2006

Anthranilate synthase in
Pseudomonas putida
is a two component enzyme system. The proteins, termed AS I and AS II, have respective molecular weights of 65,000 and 18,000. Five additional
Pseudomonas
species, both tryptophan requiring and independent strains, were examined and all were shown to contain similar two component systems. Anthranilate formation by „amide transfer,” with L-glutamine as nitrogen donor, requires both proteins; „amination,” utilizing ammonium ion, proceeds at pH 9 with only the larger component, AS I. The product of the
P. putida trpA
gene, AS I, carries the chorismate binding and tryptophan feedback inhibition sites whereas the smaller component, AS II, functions in glutamine binding. We have not been able to prepare mutants lacking AS II activity nor have other catalytic activities been detected for this protein.

The second step unique to tryptophan biosynthesis is catalyzed by phosphoribosyl transferase, in
P. putida
the
trpB
gene product. Phosphoribosyl transferase, EC 2.4.2.14, is separable from both AS I and II, and is not required for anthranilate synthesis. This chromosomal and protein organization differs from the array found in the enteric bacteria where phosphoribosyl transferase carries also the AS CoII enzymic activity.

Among the six
Pseudomonas
species examined, two groups may be distinguished on the basis of subunit complementation, the
putida-aeruginosa
(p-a), and the
acidovorans-testosteroni
(c-t). Within these groups the hybrid enzymes are equivalent in activity to the native enzyme and the level of subunits required is comparable. Between the groups the hybrid enzymes are lower in activity than either native form. The c-t components separate with difficulty and the aggregate appears to be larger than the more freely dissociable p-a complex.
P. stutzeri
resembles the p-a class and
P. multivorans
the c-t class.
Biogenesis of Mitochondria, XVIII. A New Class of Cytoplasmically Determined Antibiotic Resistant Mutants in
Saccharomyces cerevisiae
Authors: Bunn Clive L. , Mitchell Carolyn H. , Lukins H. B. , Linnane Anthony W.
Published: May 2006

New mutant yeasts resistant to the antibiotics chloramphenicol and mikamycin were isolated. They are mitochondrial mutants, characterized by several criteria as cytoplasmically determined. Biochemical studies show that amino acid incorporation into protein
in vitro
by mitochondria isolated from cells resistant or sensitive to mikamycin or chloramphenicol is inhibited by these antibiotics. Although aerobically-grown resistant strains of
Saccharomyces cerevisiae
are not affected by mikamycin or chloramphenicol, it is found that the mitochondrial protein-synthesizing system of anaerobically grown cells is inhibited
in vivo
. Cross resistance among the antibiotics chloramphenicol, mikamycin, erythromycin, lincomycin, carbomycin, and spiramycin is reported. All erythromycin resistant mutants, unlike the others, are resistant to erythromycin
in vivo
and
in vitro
. The results indicate that some of the cytoplasmic mutations (mikamycin and chloramphenicol resistance) are expressed at the mitochondrial membrane, whereas others (erythromycin resistance) possibly reflect changes in mitochondrial ribosomal proteins. We further suggest that conformational changes, either in the membranes or ribosomes, are likely to account for the observed antibiotic cross resistances.
Surveyor Substrates: Energy-Transfer Gauges of Active Center Topography during Catalysis
Authors: Latt S. A. , Auld D. S. , Vallee B. L.
Published: May 2006

An approach is described for the simultaneous measurement of catalysis, the distance from an active-site moiety to fluorescent substrate moieties of an enzyme substrate complex, and the microenvironment of such substrate groups. It is illustrated by means of a three-component energy transfer relay system, consisting of cobalt carboxypeptidase, its fluorescent dansylated peptide substrates, and tryptophanyl residues of the enzyme. The mode of procedure can be applied generally to yield conjoint information on functional and structural aspects of active centers of enzymes.
Isolation and Characterization of Calcifying Matrix Vesicles from Epiphyseal Cartilage
Authors: Ali S. Y. , Sajdera S. W. , Anderson H. C.
Published: May 2006

Matrix vesicles, associated with initial calcification in cartilage, have been isolated from bovine fetal epiphyseal cartilage. Cartilage was digested with collagenase, then partitioned into seven fractions by differential centrifugation. The cellular fractions contained over 80% of the DNA in the digest. The extracellular fraction that contained matrix vesicles, in which apatite crystals were often seen on electron microscopy, also displayed the highest specific activity for alkaline phosphatase, pyrophosphatase, ATPase, and 5′-AMPase (EC 3.1.3.1., 3.6.1.1, 3.6.1.3, and 3.1.3.5, respectively). Most of the acid phosphatase (EC 3.1.3.2) activity, on the other hand, was found in the cellular fractions, indicating that matrix vesicles are quite distinct from lysosomes. This appears to be the first instance of isolation of membrane-bounded extracellular particles from any normal tissue.

The matrix vesicles possess enzymes that can increase the local concentration of orthophosphate and thus could lead to the formation of hydroxyapatite. The membrane-bounded matrix vesicles may also provide a mechanism for ATP-dependent transport of calcium or phosphate into the lumen of the vesicles with resultant mineralization.
Initiation of Rabbit Hemoglobin Synthesis: Methionine and Formylmethionine at the N-Terminal
Authors: Yoshida Akira , Watanabe Sumiko , Morris Josephine
Published: May 2006

Ribosome-bound peptides were prepared from rabbit reticulocytes incubated in a reaction mixture that contained all essential amino acids except tryptophan. The peptides were fractionated by Sephadex gel filtration and the N-termini of these peptides were examined. Longer uncompleted hemoglobin chains (larger than 30 amino acids) had unblocked valine at the N-terminal position. In contrast, shorter initial parts of chains (smaller than 16 amino acids) did not have valine at the N-terminal position. These small peptides had methionine at the N-terminal, and 8% of the terminal methionine was presumably formylated. These findings indicate that hemoglobin chains are initiated from methionine or
N
-formylmethionine (or from both methionine and
N
-formylmethionine), and that the methionyl residue is hydrolyzed at an early stage of chain elongation.
Differences between the Ribonucleic Acids of Transforming and Nontransforming Avian Tumor Viruses
Authors: Duesberg Peter H. , Vogt Peter K.
Published: May 2006

The 60–70S RNAs of several transforming and nontransforming avian tumor viruses have different electrophoretic mobilities. The RNA of transforming viruses contains two electrophoretically separable subunit classes:aandb. The relative concentrations of these subunits vary with the virus strain. Avian leukosis viruses and nontransforming derivatives of a sarcoma virus lack subunits of classa. It is suggested that the presence of the classasubunit is related to the transforming ability for fibroblasts of the virus.