bluuebunny/crossref_metadata_2025 huggingface dataset:
PHYSIOLOGICAL ROLE OF 70
S
RIBOSOMES IN BACTERIA
Authors: Algranati Israel D. , Gonzalez Nelida S. , Bade Ernesto G.
Published: May 2006

Evidence is presented indicating that free 70S ribosomes are real components of
Bacillus stearothermophilus
and
Escherichia coli
in exponential and stationary phases of growth.

After pulses of radioactive leucine or uracil were given, protein synthesis was instantaneously stopped by chloramphenicol, or polypeptide growth was allowed to proceed to completion in slowly cooled cells. Analysis of label distribution in sucrose gradients showed that 70S monomers, and not subunits, are final products of translation.

A ribosome cycle for protein synthesis in bacteria is proposed.
VIRUS-SPECIFIC NUCLEIC ACIDS IN SV40-EXPOSED HAMSTER EMBRYO CELL LINES: CORRELATION WITH S AND T ANTIGENS
Authors: Levin Myron J. , Oxman Michael N. , Diamandopoulos George Th. , Levine Arthur S. , Henry Patrick H. , Enders John F.
Published: May 2006

A number of homologous SV40-exposed hamster embryonic cell lines were examined for the presence of RNA complementary to SV40 DNA. Only those lines containing the SV40 T antigen were found to have such virus-specific RNA. In lines containing the SV40 S antigen, but not the SV40 T antigen, virus-specific RNA was not detected. These findings suggest that the S antigen is not coded for directly by the SV40 genome.
23
Na NUCLEAR MAGNETIC RESONANCE RELAXATION STUDIES OF SODIUM ION INTERACTION WITH SOLUBLE RNA
Authors: James Thomas L. , Noggle Joseph H.
Published: May 2006

Interactions between
23
Na
+
and soluble RNA in aqueous solution are studied with the use of
23
Na nuclear magnetic resonance. At low concentrations of NaCl, the interactions obey a simple equilibrium model with a formation constant log (

K
f

)
3
= 2.8 ± 0.3. The relaxation rate of the bound sodium is found to be
T

1
B

-1
= 222 ± 19 sec
-1
compared to that of free sodium
T

1
F

-1
= 17.5 sec
-1
. At high NaCl concentrations, the system deviates from the model, possibly owing to aggregation of the soluble RNA.
FLEXIBILITY OF SUPPOSED “RIGID” MOLECULES: SUBSTITUTED 2,5-PIPERAZINEDIONES (DIKETOPIPERAZINES)
Authors: Benedetti E. , Corradini P. , Goodman M. , Pedone C.
Published: May 2006

The relevant results of accurate X-ray analyses of both the
trans
-and the L-
cis
-3,6-dimethyl-2,5-piperazinediones (diketopiperazines) are reported. We note that a large variability of conformations for the ring system can be accomplished by coupling small bond-angle deformations with large variations of the internal rotation angles. The experimental molecular models are discussed in terms of these changes and in terms of nonbonded intramolecular interactions.
SYNTHESIS OF A MODEL SYSTEM FOR THE PRIMARY ENERGY CONVERSION REACTIONS IN PHOTOSYNTHESIS
Authors: Wang Jui H.
Published: May 2006

A model system is constructed which, like the photosynthetic apparatus of green plants, can convert light to chemical free energy through pigment-sensitized photooxidation of water. The system has two light-harvesting subunits connected electrically in series. Each subunit is made of a multimolecular layer of Zn(II)-tetraphenylporphyrin deposited on a clean aluminum surface and immersed in an aqueous mixture of potassium ferri- and ferrocyanide. Upon illumination by amber light, charge transfer takes place across more than 70 molecular layers of the pigment with a photoelectromotive force of 1.1 to 1.3 volts per subunit. With NADP as the electron acceptor and NADP-reductase as a mediator, the system can photooxidize water to oxygen gas. With these model experiments as a guide, a molecular mechanism for the primary energy conversion reactions in photosynthesis is formulated that offers a unified interpretation of most of the relevant observations reported in the literature.
ON THE ASSOCIATION OF TYROCIDINE WITH ACETYLCHOLINESTERASE
Authors: Changeux Jean-Pierre , Ryter Antoinette , Leuzinger Walo , Barrand Plana , Podleski Thomas
Published: May 2006

In studies of several polypeptide antibiotics with a high affinity for a variety of biological membranes, tyrocidine was found to bind specifically to acetylcholinesterase, an enzyme localized in excitable membranes. Several other polypeptides tested were not bound. Tyrocidine reversibly inhibits acetylcholinesterase formed by homogeneous protein, but seems to have no effect on the activity of the enzyme bound to the eel electroplax membrane. This inhibition is accompanied by a reversible association of the soluble enzyme in to ordered and rapidly sedimenting aggregates of large molecular weight. Electron micrographs of acetylcholinesterase are shown which are consistent with the chemical evidence of the existence of four subunits.
OLFACTORY BULB REMOVAL: EFFECTS ON BRAIN NOREPINEPHRINE
Authors: Pohorecky Larissa A. , Zigmond Michael J. , Heimer Lennart , Wurtman Richard J.
Published: May 2006

Removal of one olfactory bulb causes marked changes in the norepinephrine contents of several brain regions. The brainstem catecholamine level is higher on the side of the lesion than on the control side, whereas telencephalic norepinephrine is lower ipsilateral to the lesion. The apparent decline in telencephalic norepinephrine is associated with a parallel decrease in the ability of this region to take up and retain
3
H-norepinephrine injected into the lateral cerebral ventricle. Within the ipsilateral olfactory tubercle, there is also a significant decrease in the activity of the enzyme phenylethanolamine-
N
-methyl transferase, which catalyzes the conversion of norepinephrine to epinephrine. The results of this study suggest that measurement of changes in the uptake of
3
H-norepinephrine injected into the cerebral ventricle can be used as a technique for mapping central adrenergic pathways.
THE MECHANISM OF ACTION OF RIBONUCLEASE
Authors: Roberts Gordon C. K. , Dennis Edward A. , Meadows Donella H. , Cohen Jack S. , Jardetzky Oleg
Published: May 2006

The possible mechanisms of action of bovine pancreatic ribonuclease are discussed in the light of the detailed knowledge of the geometry of the active site that has been derived from studies of inhibitor binding by X-ray diffraction and nuclear magnetic resonance. When combined with a knowledge of the mechanism of phosphate ester hydrolysis, this information imposes severe geometric constraints on possible mechanisms of action of the enzyme. Two types of mechanism can be distinguished, the linear and the pseudorotation. The linear mechanism includes a catalytic role for both histidine residues at the active site and does not involve pseudorotation of the intermediate. In contrast, in the pseudorotation mechanism one histidine residue performs all the catalytic functions, while the other serves only to bind the phosphate anion; this necessarily involves pseudorotation of the intermediate and specific protonation of the leaving group by the enzyme.

The mode of binding of the product of the reaction, cytidine-3′-monophosphate, has been elucidated by X-ray diffraction and nuclear magnetic resonance. If the substrate binds in an analogous way, only the linear mechanism is possible. This mechanism is described in detail.
POLYPEPTIDE CHAIN INITIATION IN
E. coli
: ISOLATION OF HOMOGENEOUS INITIATION FACTOR F
2
AND ITS RELATION TO RIBOSOMAL PROTEINS
Authors: Chae Yung-Bog , Mazumder Rajarshi , Ochoa Severo
Published: May 2006

Previous work has shown that F
2
, one of several ribosomal factors involved in polypeptide chain initiation, functions in the binding of formylmethionyl-transfer RNA (fMet ∼ tRNA
f
) to a messenger RNA-ribosome complex. F
2
was isolated from 1.0
M
ammonium chloride washes of
E. coli
Q13 ribosomes as a protein homogeneous on polyacrylamide gel electrophoresis at both pH 4.5 and 7.8. Its molecular weight is approximately 80,000. Comparison of electrophoretic patterns of ribosomal proteins from NH
4
Cl-washed and unwashed ribosomes and F
2
, at pH 4.5, shows that F
2
corresponds to the slowest-moving component of the proteins derived from unwashed ribosomes. This component is missing from the NH
4
Cl-washed ribosomes. The activity of F
2
is stimulated by two additional factors, initiation factor F
1
and a factor(s) present in a narrow ammonium sulfate fraction of the ribosomal NH
4
Cl wash. The nature of the latter is unknown.
TRANSFER RNA, III. RECONSTITUTION OF ALANINE ACCEPTOR ACTIVITY FROM FRAGMENTS PRODUCED BY SPECIFIC CLEAVAGE OF tRNA
Ala
II
AT ITS ANTICODON
Authors: Imura Nobumasa , Schwam Harvey , Chambers Robert W.
Published: May 2006

This report describes experiments showing that tRNA
Ala
II
can be cleaved specifically at the G residue of its anticodon to give “half” molecules in high yield. Neither of these fragments has alanine-acceptor activity, but this activity can be reconstituted by mixing the fragments in the presence of Mg
+2
. In dilute salt, on the other hand, the active complex dissociates spontaneously at 25° into the two fragments. Thus, both “halves” of tRNA
Ala
II
are necessary for acceptor activity and, in the presence of Mg
+2
, combination of these fragments to give an active duplex is thermodynamically favorable.
SOME PROPERTIES OF THE MICROSOMAL 2,3-OXIDOSQUALENE STEROL CYCLASE
Authors: Yamamoto Shozo , Lin Kang , Bloch Konard
Published: May 2006

The transformation of 2,3-oxidosqualene to lanosterol is catalyzed by a microsomal enzyme (cyclase) which can be obtained in soluble and partially purified form by treatment of liver microsomes with deoxycholate as previously shown. The catalytic and physical properties of the soluble enzyme are determined by ionic strength. In 0.4
M
KCl the cyclase exists largely in a dissociated, enzymatically active form. Solutions of low ionic strength (0.1
M
KCl or less) cause enzyme aggregation and loss of activity. The anionic detergent deoxycholate is essential for cyclase activity, but is effective only in a narrow concentration range.
MOTION OF STEROID SPIN LABELS IN MEMBRANES
Authors: Hubbell Wayne L. , McConnell Harden M.
Published: May 2006

Steroid spin labels have been found to undergo rapid and sometimes anisotropic rotational motion in membranes and phospholipid vesicle preparations. N-oxyl-4′,4′-dimethyloxazolidine derivatives of 5α-androstan-3-one-17β-ol, 5β-androstan-3-one-17β-ol, and 5α-androstan-3-one were prepared according to the procedure described by Keana. The paramagnetic five-membered ring is rigidly attached to the steroid nucleus at the 3-position, and thus the resonance spectrum of the nitroxide group reflects the motion of the entire steroid nucleus. This rapid motion, with rotational diffusion frequencies of the order of 10
7
to 10
8
second
-1
is considered to lend plausibility to models of membrane transport involving rotations and/or translations of carriers within the hydrophobic region of the membrane. The steroid spin labels also form a convenient class of probes for studying conformational changes in membranes, since (
a
) their resonance spectra often fall in the category of “intermediate immobilization,” which is most sensitive to small changes, and (
b
) these labels are quite soluble in a wide variety of membranes.
PEPTIDE CHAIN TERMINATION, III. STIMULATION OF
in vitro
TERMINATION
Authors: Milman G. , Goldstein J. , Scolnick E. , Caskey T.
Published: May 2006

Throughout extensive purification, the release factors R
1
and R
2
each behave as a single molecular species with alternate codon recognition (R
1
, UAA or UAG; R
2
, UAA or UGA). The release of f[
3
H]methionine from f[
3
H]-Met-tRNA·AUG·ribosome complex requires R factor and terminator codon and does not appear to require tRNA or transfer factors T and G. Purification of the components of the release assay has enabled identification of a protein factor S in the 55-80 per cent ammonium sulfate fraction of
E. coli
B supernatant fraction which stimulates the rate but not the extent of release dependent upon R factor and appropriate termination codon. The S factor has properties similar to T, but further purification is required to determine the nature and function of S in peptide chain termination.
PREPARATION OF FOUR NEW ANTIBIOTICS FROM A MUTANT OF
Streptomyces fradiae
Authors: Shier W. Thomas , Rinehart Kenneth L. , Gottlieb David
Published: May 2006

A mutant of
Streptomyces fradiae 3535
incapable of synthesizing the antibiotic neomycin in the absence of added deoxystreptamine, the aminocyclitol subunit of the antibiotic, has been isolated from a culture treated with
N
-methyl-
N
′-nitro-
N
-nitrosoguanidine. The related aminocyclitols streptamine and 2-epistreptamine, both available by chemical synthesis, were incorporated by the mutant strain into four new antibiotics, for which we suggest the names hybrimycins A (isomers 1 and 2, from streptamine) and hybrimycins B (isomers 1 and 2, from 2-epistreptamine). Structures of the new antibiotics were established from the mass spectral, nuclear magnetic resonance, and optical rotatory properties of appropriate derivatives. This method offers a promising approach to the synthesis of other antibiotics.
LOCALIZATION AND SECRETION OF SALT BY THE SALT GLANDS OF
Tamarix aphylla
Authors: Thomson W. W. , Berry W. L. , Liu L. L.
Published: May 2006

Analysis of salt secreted by the salt glands of
Tamarix aphylla
shows that the composition of the secreted salt is dependent on the salt composition of the root environment. Rubidium ion, if added to culture solutions in which the plants were growing, is also taken up by the plants and subsequently secreted by the glands. Electron micrographs of glands from the ribidium-secreting plants show accumulations of electron-dense material in the microvacuoles of the secretory cells. It is concluded that rubidium is accumulated in the microvacuoles and subsequently secreted by their fusion with the plasmalemma.
THE EFFECTS OF RESERPINE, α-METHYLTYROSINE, AND L-3,4-DIHYDROXYPHENYLALANINE ON BRAIN TYROSINE TRANSAMINASE
Authors: Gibb James W. , Webb Jerry G.
Published: May 2006

The effects of a variety of pharmacological and physiological manipulations on the activity of hepatic tyrosine transminase have been extensively investigated. Brain tyrosine transaminase, however, has received only limited attention. Since tyrosine transaminase may be important in the regulation of catecholamine biosynthesis in the brain, the effects of agents affecting catecholamine storage and synthesis on brain tyrosine transamination were investigated. Transamination in the 12,000 ×
g
fraction was measured by a radioactive procedure. α-Methyltyrosine and reserpine, agents which deplete brain catecholamines, decreased tyrosine transaminase activity. Administration of the catecholamine precursor, L-3,4-dihydroxyphenylalanine to the reserpine-and α-methyltyrosine-treated rats elevated the tyrosine transaminase activity to normal. The possible implications of these findings in the regulation of the biosynthesis of the catecholamines are discussed.
VITAMIN D
3
-STIMULATED TEMPLATE ACTIVITY OF CHROMATIN FROM RAT INTESTINE
Authors: Hallick Richard B. , DeLuca Hector F.
Published: May 2006

Administration of vitamin D to rats deficient in this vitamin markedly increases the template activity for DNA-dependent RNA synthesis by rat intestinal mucosal chromatin. The maximum stimulation of template activity occurs three hours after a dose of 2000 international units of vitamin D
3
is given. These results support the concept that vitamin D functions by initiating the transcription of DNA into mRNA, which codes for functional protein(s) involved in calcium transport in the small intestine.
EFFECT OF 5-BROMODEOXYURIDINE ON EXPRESSION OF CULTURED CHONDROCYTES GROWN
in vitro
Authors: Holthausen H. Schulte , Chacko S. , Davidson E. A. , Holtzer H.
Published: May 2006

Exposure of cultured cartilage cells to 5-bromodeoxyuridine results in a rapid loss of the ability to synthesize the chondroitin 4-sulfate-protein complex characteristic of the extracellular matrix of differentiated cartilage. UDP-glucose dehydrogenase, UDP-
N
-acetyl hexosamine 4-epimerase and the enzyme system responsible for catalyzing 3′-phosphoadenosine-5′-phosphosulfate synthesis all progressively decline in activity, while several other cellular processes seem unaffected. However, there are marked morphological changes which may be associated with plasma membrane components or the synthesis of the protein-polysaccharide complex.
HEMOGLOBIN A: AN ELECTRON PARAMAGNETIC RESONANCE STUDY OF THE EFFECTS OF INTERCHAIN CONTACTS ON THE HEME SYMMETRY OF HIGH-SPIN AND LOW-SPIN DERIVATIVES OF FERRIC ALPHA CHAINS
Authors: Peisach J. , Blumberg W. E. , Wittenberg B. A. , Wittenberg J. B. , Kampa L.
Published: May 2006

Hemoglobin, the oxygen-binding heme protein of blood is composed of four subunits of two types, alpha and beta. Although the protein when isolated is diamagnetic, by oxidation it can be converted to various paramagnetic ferric forms exhibiting specific electron paramagnetic resonance (EPR) spectra. Using electron paramagnetic resonance, we have shown that the symmetry of the heme of isolated ferric alpha chains is different from that of the heme of these same subunits when associated with ferric beta chains in the parent tetramer. The high-spin form of the isolated ferric alpha chains shows a clearly resolved departure from tetragonal symmetry in contrast to ferrihemoglobin A, where the environment of the iron of all four chains is nearly tetragonal. This difference in heme symmetry suggests that the maintenance of tetragonal symmetry in the hemoglobin tetramer must be brought about by the configuration the alpha chains assume due to their contact with the beta chains. When isolated from the tetramer, some parts of the alpha chain must undergo physical displacement from a configuration that had been stabilized by the beta chains.

Although differences in symmetry between monomer and tetramer are seen with high-spin forms, no such difference exists with two low-spin ferric forms. Here the symmetries of iron are primarily governed by the immediate ligand environment of the iron and not by the state of association of the protein.
MÖSSBAUER SPECTROSCOPY OF THE IRON-SULFUR PROTEINS
Authors: Johnson C. E. , Bray R. C. , Cammack R. , Hall D. O.
Published: May 2006

The Mössbauer spectra of
57
Fe in two plant ferredoxins (from spinach and
Euglena
) and in xanthine oxidase have been measured at a series of temperatures and magnetic fields, and are found to be similar in all three proteins. In the oxidized state the iron is nonmagnetic. In the reduced state, the iron nuclei show magnetic hyperfine interaction with an electron spin
S
of ½, producing an effective field of about 180 kG at the nuclei.
GANGLIOSIDES IN DNA VIRUS-TRANSFORMED AND SPONTANEOUSLY TRANSFORMED TUMORIGENIC MOUSE CELL LINES
Authors: Mora Peter T. , Brady Roscoe O. , Bradley Roy M. , McFarland Vivian W.
Published: May 2006

In mouse cell lines transformed by SV40 virus, a decrease was observed in the higher ganglioside homologues disialo-ceramidetetrahexoside and monosialo-ceramidetetrahexoside. Such change was observed only in cells which carry the virus genome, and it correlated with increased saturation density in tissue culture and with rejection in immunologically competent syngeneic host. This indicates that the change is one of the virus-regulated functions, and it is postulated that it relates to the rejection of the virus-transformed cells.
MECHANISM OF DNA CHAIN GROWTH, III. EQUAL ANNEALING OF T4 NASCENT SHORT DNA CHAINS WITH THE SEPARATED COMPLEMENTARY STRANDS OF THE PHAGE DNA
Authors: Sugimoto Kazunori , Okazaki Tuneko , Imae Yasuo , Okazaki Reiji
Published: May 2006

Nascent short DNA chains isolated from T4-infected
E. coli
under a variety of conditions anneal equally to the separated complementary phage DNA strands. The samples examined include: pulse-labeled short chains isolated by alkaline sucrose gradient sedimentation from the T4D (wild type)-infected cells in both the early and late stages of phage DNA synthesis; nascent chains accumulated during ligase inhibition of T4
ts
B20-infected cells; and the single-stranded nascent short chains isolated from T4D-infected cells by mild procedures involving no denaturation treatment. The results are consistent with the hypothesis that
both
strands of DNA are synthesized discontinuously.
BACTERIOPHAGE T4 DNA-DEPENDENT
in vitro
SYNTHESIS OF LYSOZYME
Authors: Schweiger Manfred , Gold Lawrence M.
Published: May 2006

A cell-free system derived from uninfected
Escherichia coli
previously was shown to synthesize β-glucosyl transferase in response to T4 DNA. This same
in vitro
system, when incubated at slightly higher magnesium concentrations, also synthesized enzymatically active lysozyme. The lysozyme activity that appeared was judged to be T4-specific since antibodies prepared against authentic T4-lysozyme inactivated the
in vitro
synthesized enzyme. DNA from a T4 mutant carrying a deletion in the lysozyme gene stimulated amino acid incorporation to the same extent as wild-type T4 DNA but was inactive in directing the synthesis of lysozyme. Various inhibitors of RNA and protein synthesis inhibited the
in vitro
synthesis of lysozyme.
INTERACTION OF THE CARBOHYDRATE-BINDING PROTEIN CONCANAVALIN A WITH NORMAL AND TRANSFORMED CELLS
Authors: Inbar Michael , Sachs Leo
Published: May 2006

It has been shown that the carbohydrate-binding protein concanavalin A (ConA) can agglutinate leukemic cells and cells transformed by polyoma virus, simian virus 40, chemical carcinogens, and X-irradiation. This protein did not agglutinate normal cells under the same conditions. The agglutination was reversed by competition with α-methyl-D-glucopyranoside (α-MG), a carbohydrate that strongly binds to ConA, but not by the carbohydrates α-methyl-L-fucopyranoside or N-acetylglucosamine, with no binding or weak binding to ConA. Destruction of the α-MG binding sites of the native protein by removal of bivalent metal ions abolished the agglutination produced by the native protein. The treatment of cells with trypsin resulted in the agglutination of normal cells by ConA and a decrease of agglutinability of transformed cells. When nonagglutinating untransformed 3T3 cells were infected with simian virus 40 and normal rat cells were infected with polyoma virus, the infected cells became agglutinable several days after virus infection. The percentage of cells agglutinated, about 50 per cent, was much higher than the percentage of cells hereditarily transformed. The results indicate that the surface membrane of transformed cells contains sites that interact with the α-MG binding sites of ConA, that such sites can be found on the surface membrane of normal cells after treatment with trypsin, and that the change in the surface structure from normal to transformed occurs in cells that are abortively transformed.
IMMUNOCHEMICAL HOMOLOGIES AMONG SUBUNITS OF TROUT LACTATE DEHYDROGENASE ISOZYMES
Authors: Holmes Roger S. , Markert Clement L.
Published: May 2006

Lactate dehydrogenase is a tetrameric enzyme, generally composed of one or two kinds of subunits each encoded in a separate gene. Most vertebrates synthesize five major isozymic forms of lactate dehydrogenase, but the salmonid fish, particularly trout, synthesize many more. The numerous lactate dehydrogenase isozymes of trout can be selectively removed from tissue homogenates by suitably prepared antisera to specific lactate dehydrogenase subunits of fish. Electrophoretic resolution of such antisera-treated homogenates then permits an identification of each isozyme and a determination of its subunit composition and probable genetic basis. Such data indicate that trout are tetraploid organisms and have duplicate and slightly different loci for two and perhaps three of the lactate dehydrogenase loci found in other fish. The evolutionary relationships among the lactate dehydrogenase loci can also be assessed by these immunochemical data.
SPECIFICITY IN THE ASSEMBLY OF MULTISUBUNIT PROTEINS
Authors: Cook Robert A. , Koshland D. E.
Published: May 2006

The recoveries of activity in the presence of mixtures of several enzymes and a cellular debris were compared with the recoveries of the pure enzymes. In the acid-dissociation experiments, no interference from foreign proteins was observed nor were any cross hybrids between subunits of different enzymes found. This suggests that the intersubunit binding sites are highly specific and have been selected over evolutionary time for correct assembly. In the urea experiments, cross hybridization and decreased yields were observed in a few cases but in most cases the “foreign” unfolded chains did not influence the recovery of the test enzyme. The results suggest that compartmentalization, temporal or spatial, will not be required as far as assembly of subunits of cytoplasmic enzymes is concerned. The results suggest some cross reaction might occur if all peptide chains were unfolding together. If folding occurs during or immediately after translation, this difficulty would be avoided.
THE STRUCTURE OF CARBOXYPEPTIDASE A, IX. THE X-RAY DIFFRACTION RESULTS IN THE LIGHT OF THE CHEMICAL SEQUENCE
Authors: Lipscomb William N. , Hartsuck Jean A. , Quiocho Florante A. , Reeke George N.
Published: May 2006

Several features of carboxypeptidase A (CPA) which were previously established by the X-ray diffraction structure studies have now been confirmed by the chemical sequence analysis. These results include the number (307) of amino acid residues in CPA
α
, the identities of the residues (Arg 145, Glu 270, and Tyr 248) shown by the X-ray study to be involved in substrate binding and catalysis, and the existence of a disulfide bond.

The Zn ligands, shown by the X-ray study to be residues 69, 72, and 196 and identified as His, Glx, and either Glx or Lys, are proved by the chemical sequence to be His, Glu, and His, respectively.

No change is required in our previous mechanistic deductions, which are here extended to include a specific mechanism of activation of the substrate by a net charge on the metal ion, which suffers a change in local dielectric constant when it is covered by a substrate.
IMMUNOGLOBULIN SYNTHESIS AND SECRETION, III. INCORPORATION OF GLUCOSAMINE INTO IMMUNOGLOBULIN ON POLYRIBOSOMES
Authors: Sherr Charles J. , Uhr Jonathan W.
Published: May 2006

Mouse myeloma cells were pulse-labeled
in vitro
with
3
H-D-glucosamine and
14
C-L-leucine. Analysis on sucrose gradients revealed incorporation of both isotopes into polyribosomes and release of most of such radioactivity after treatment of labeled cells
in vitro
with puromycin. A mixing experiment excluded the
in vitro
binding to unlabeled polyribosomes of
3
H-glucosamine in labeled post-ribosomal material. Polyribosomes labeled with
3
H-glucosamine were precipitated with antiserum specific for mouse immunoglobulin. By chromatography and gel filtration, the precipitable radioactivity was shown to be glucosamine covalently bound to heavy and light chains.
THE RELATION BETWEEN PEROXIDASE ACTIVITY AND THE MORPHOLOGICAL EXPRESSION OF THE HOODED GENE IN BARLEY
Authors: Stebbins G. L. , Gupta V. K.
Published: May 2006

Reproductive meristems of the hooded (KK) genotype of barley at the stage of young lemma primordia were injected with the inhibitors sodium azide, hydrazine, and hydroxylamine at concentrations of 10
-3
, 10
-4
, and 10
-5
M
, as well as with phenylboric acid. These treatments all brought about an altered expression of the adult phenotype in the direction of awned (kk) genotype. Analysis of tissues treated with the same reagents revealed a reduction in peroxidase activity which was proportional to the effect of each inhibitor in modifying the phenotypic expression of the gene. Exogenous IAA injected in the same manner brought about a similar modification of the phenotype and parallel reduction of peroxidase activity, but to a lesser degree. These results are believed to be caused by modifications of the action of the IAA oxidase system in the developing meristems.
FOOT-AND-MOUTH DISEASE VIRUS INHIBITION INDUCED IN MICE BY SYNTHETIC DOUBLE-STRANDED RNA (POLYRIBOINOSINIC AND POLYRIBOCYTIDYLIC ACIDS)
Authors: Richmond J. Y. , Hamilton L. D.
Published: May 2006

Synthetic 2-stranded RNA—a helical complex formed by duplexing homopolymers of polyriboinosinic and polyribocytidylic acids (poly I:C)—induced host resistance to foot-and-mouth disease virus when microgram quantities were injected into mice. There was a graded response as shown by titrations of polynucleotide complex or virus. Protection was effective for >48 hours after a single injection of polynucleotide complex. Survival and serum interferon titers were directly related.
SOME BILINEAR GENERATING FUNCTIONS
Authors: Srivastava H. M.
Published: May 2006

In the present paper, the author applies some of his earlier results which extend the well-known Hille-Hardy formula for the Laguerre polynomials to certain classes of generalized hypergeometric polynomials in order to derive various generalizations of a bilinear generating function for the Jacobi polynomials proved recently by Carlitz. The corresponding results for the polynomials of Legendre, Gegenbauer (or ultraspherical), Laguerre, etc., can be obtained fairly easily as the specialized or limiting cases of the generating functions presented here. It is also shown how the formula of Carlitz follows rather rapidly from a result of Weisner involving the Gaussian hypergeometric functions.
DISSOCIATION OF 70S RIBOSOMES: SOME PROPERTIES OF THE DISSOCIATING FACTOR FROM
Bacillus stearothermophilus
AND
Escherichia coli
Authors: Bade Ernesto G. , González Nelida S. , Algranati Israel D.
Published: May 2006

A protein factor which produces
in vitro
dissociation of 70
S
particles into 30
S
and 50
S
subunits has been obtained from
Bacillus stearothermophilus
and
Escherichia coli
. The factor could be extracted from ribosomes, polyribosomes, and S100 supernatant.

The kinetics and temperature curve of the dissociation process in the
B. stearothermophilus
system have been studied and compared with the reaction in the
E. coli
system.

No species specificity was observed when hybrid mixtures of ribosomes and dissociating factor from both bacteria were used. The wide variations of dissociating activity in cells at different stages of growth and the capacity of the liberated subunits to carry out polypeptide synthesis suggest that the dissociating factor has a physiological role.
THE POLYAMINE CONTENT OF THE tRNA OF
E. coli
Authors: Cohen Seymour S. , Morgan Sophronia , Streibel Ellen
Published: May 2006

A sensitive method of polyamine estimation has been adapted to the study of the organic cations of small amounts of nucleic acid. A procedure utilizing phenol extraction, alcohol precipitation, and separation on Sephadex G100 has been devised for the isolation of tRNA at low ionic strength. The procedure is applicable to the isolation of tRNA from liter batches of bacterial culture. With these methods we have examined the polyamines of tRNA isolated from polyauxotrophic strains of
E. coli
incubated under various physiological conditions and have found the following: (1) The tRNA from relaxed bacteria (TAU rel) harvested during exponential growth is heterogeneous with respect to polyamine content. Some portions of the population contain about one mole of spermidine per mole of tRNA. Some putrescine and an unknown amine are also present in low concentration. (2) After exponential TAU rel is incubated with thymine and uracil in the absence of arginine, the tRNA population is far more homogeneous with respect to polyamine content. The various fractions contain two moles of spermidine per mole of tRNA and a small amount of putrescine. (3) After exponential TAU rel is incubated in the absence of both arginine and uracil, the polyamine pattern of the tRNA resembles that isolated from exponential cells. (4) The tRNA from stringent bacterias harvested during exponential growth is heterogeneous with respect to polyamine distribution and some fractions contain relatively high concentrations of the unknown amine.
STUDIES ON THE FORMATION OF TRANSFER RIBONUCLEIC ACID-RIBOSOME COMPLEXES, XI. ANTIBIOTIC EFFECTS ON PHENYLALANYL-OLIGONUCLEOTIDE BINDING TO RIBOSOMES
Authors: Pestka Sidney
Published: May 2006

The effect of antibiotics on the binding of phenylalanyl-oligonucleotide to ribosomes has been examined. The results show that many classes of antibiotics can interfere with binding of the aminoacyl-oligonucleotide terminus of tRNA to ribosomes: chloramphenicol, sparsomycin, D-WIN-5094, vernamycin A, PA114A, streptogramin, amicetin, gougerotin, tylosin, and spiramycin III. The results are consistent with the hypothesis that these antibiotics inhibit protein synthesis by interfering with the binding of the aminoacyl-end of aminoacyl-tRNA to ribosomes.
PHOTOREGULATION OF BIOLOGICAL ACTIVITY BY PHOTOCROMIC REAGENTS, II. INHIBITORS OF ACETYLCHOLINESTERASE
Authors: Bieth Joseph , Vratsanos Spyros M. , Wassermann Norbert , Erlanger Bernard F.
Published: May 2006

The enzymic activity of acetylcholinesterase can be photoregulated through the mediation of photochromic inhibitors of the enzyme.
N-p
-phenylazophenyl-
N
-phenylcarbamyl fluoride, an irreversible inhibitor of acetylcholinesterase, exists as two geometric isomers which are interconvertible through the action of light. The
cis
isomer, which predominates after exposure to light of 320 nm, is more active than the
trans
isomer, which results from exposure to light of 420 nm. It was possible, therefore, to use light energy to regulate the inactivation of the enzyme. Similarly, levels of acetylcholinesterase activity could be photo-regulated in a completely reversible manner by means of the photochromic reversible inhibitor
p
-phenylazophenyltrimethylammonium chloride. These experiments can serve as models for similar phenomena observed in nature, particularly in photoperiodic rhythms of higher animals.
ALGEBRAIC CHARACTERIZATION OF POLYNOMIALS WHOSE ZEROS LIE IN CERTAIN ALGEBRAIC DOMAINS
Authors: Kalman R. E.
Published: May 2006

A new algebraic criterion is given for a polynomial φ with complex coefficients to have all its zeros in a certain type of algebraic region T of the complex plane. In particular, T may be any circle or half plane. The criterion is effectively computable from the coefficients of the polynomial φ. The classical results of Hermite, Hurwitz, Lyapunov, Schur-Cohn, and others appear as special cases of the new criterion.
ENZYMATIC HYDROXYLATION OF BENZOPYRENE AND ITS RELATIONSHIP TO CYTOTOXICITY
Authors: Gelboin Harry V. , Huberman Eliezer , Sachs Leo
Published: May 2006

Aryl hydrocarbon hydroxylase, an inducible microsomal enzyme system, has been measured in cultures of normal and transformed hamster, mouse, and human cells. In order to determine the highest level of enzyme, the cells were induced by pretreatment with benz(a)anthracene. A correlation was found between the level of enzyme activity and the susceptibility of the cells to the cytotoxicity produced after treatment with benzopyrene. The results indicate that aryl hydrocarbon hydroxylase is the enzyme system responsible for cell susceptibility to the cytotoxic effect of benzopyrene and the toxic effect of benzopyrene is due to its enzymatic conversion to a cytotoxic metabolite. 3-Hydroxybenzopyrene, one of the products of the enzymatic hydroxylation of benzopyrene, was found to be cytotoxic to cells that were either susceptible or resistant to the cytotoxic effect of benzopyrene.
PEPTIDE CHAIN TERMINATION, V. THE ROLE OF RELEASE FACTORS IN MRNA TERMINATOR CODON RECOGNITION
Authors: Scolnick E. M. , Caskey C. T.
Published: May 2006

The protein release factors, R1 and R2, bind to ribosomes in response to specific terminator codons (R1 to UAA or UAG, R2 to UAA or UGA). In reactions containing ribosomes, the tritiated oligonucleotide UA[
3
H](A)
2
is retained on nitrocellulose filters in response to either R1 or R2, and UA[
3
H]G in response to R1. These results indicate that an R·terminator codon·70
S
ribosome intermediate occurs during terminator codon recognition and suggest that protein release factors R1 and R2 recognize terminator codons.
AN ATP-DEPENDENT DEOXYRIBONUCLEASE FROM
Escherichia coli
WITH A POSSIBLE ROLE IN GENETIC RECOMBINATION
Authors: Oishi M.
Published: May 2006

A DNase which requires ATP for its function was purified from
E. coli
and some of the characteristics of the purified enzyme were studied. This enzyme activity could not be detected in certain (
recB
and
recC
) recombination deficient mutant strains. The possible role of the enzyme in genetic recombination is discussed.
THE NATURE OF GENERAL BASE-GENERAL ACID CATALYSIS IN SERINE PROTEASES
Authors: Polgár L. , Bender Myron L.
Published: May 2006

The high reactivity of the serine residue at the active site of serine proteases is often attributed to the formation of a hydrogen bond between this serine and a histidine residue. In the case of the serine protease subtilisin, the catalytic serine residue can be specifically replaced by a cysteine residue and this modified enzyme is called thiol-subtilisin. By studying the D
2
O effect on acyl-enzyme formation with subtilisin and thiol-subtilisin, we present evidence that thiol-subtilisin but not subtilisin may contain a hydrogen bond. Based on the comparison of the catalytic activities of subtilisin and thiol-subtilisin, a rigid active site model for the serine proteases is proposed in which the histidine residue operates in a fixed steric position both as a general base and as a general acid, and this, rather than the formation of a hydrogen bond, accounts for the high nucleophilicity of the serine residue.
Isolation of Microtubule Protein from Cultured Mouse Neuroblastoma Cells
Authors: Olmsted J. B. , Carlson K. , Klebe R. , Ruddle F. , Rosenbaum Joel
Published: May 2006

The addition of vinblastine to high-speed supernatants derived from homogenates of cultured mouse neuroblastoma cells results in the formation of a precipitate which has been characterized as microtubule protein by the following criteria: colchicine-binding activity, molecular weight, amino acid composition, and electrophoretic mobility. The method therefore permits the rapid isolation of microtubule protein from crude supernatants of neuroblastoma cells.
Studies of Transfer RNA Tertiary Structure by Singlet-Singlet Energy Transfer
Authors: Beardsley Kenneth , Cantor Charles R.
Published: May 2006

This distance between a base next to the anticodon of tRNA and the 3′ CpCpA terminus of the molecule has been estimated by singlet-singlet energy transfer experiments. The energy donor was the
Y
base of unknown structure found in yeast tRNA
phe
. Three different energy acceptors were used: acriflavine, proflavinyl acetic acid hydrazide, and 9-hydrazino acridine. These were attached to the periodate-oxidized 3′ end of the tRNA. R
0
's between 24 and 30 Å were calculated for the three chromophore couples by assuming that the relative orientation of donor and acceptor is random. This assumption is supported by the consistency of the experimental results with all three acceptors and by studies of the fluorescence depolarization of
Y
. The energy transfer observed both by quenching of
Y
and enhanced activation of the acceptors is quite small, indicating that the anticodon is more than 40 Å away from the amino acid accepting terminus. This places severe restrictions on the type of tertiary structure possible for tRNA.
Energy Coupling in the Lactose Transport System of
Escherichia coli
Authors: Wong P. T. S. , Kashket E. R. , Wilson T. H.
Published: May 2006

A mutant (ML 308-22) was isolated from
Escherichia coli
ML 308, which had lost the normal capacity to accumulate lactose analogs despite an increase in the membrane carrier activity. The exit of thiomethylgalactoside was much faster than normal, accounting for the inability of the cell to maintain high intracellular concentrations of galactosides. Growth of the mutant on lactose was normal at high concentrations of sugar and impaired at low concentrations. This transport defect appeared to be limited to the lactose transport system as D-fucose and α-aminoisobutyric acid uptake and accumulation were normal. It is inferred from the data that the mutant possessed a defect in the coupling of metabolic energy to lactose transport.
Kinetics of Neutralization of Bacteriophage f2 by Rabbit γG-Antibodies
Authors: Dudley Mary A. , Henkens Robert W. , Rowlands David T.
Published: May 2006

The neutralization of bacteriophage f2 by intact γG-immunoglobulin or fragments is first order with respect to both bacteriophage and antibody. Minimum values for the rate constants are of the order of 10
7
M
-1
sec
-1
. The temperature dependence of the rates corresponds to the activation parameters: Δ
H
‡ = 6.7 kcal mole
-1
and Δ
S
‡ = -4 cal deg
-1
mole
-1
(γG-immunoglobulin); Δ
H
‡ = 8.0 kcal mole
-1
and Δ
S
‡ = -0.9 cal deg
-1
mole
-1
(5
S
pepsin fragment); and Δ
H
‡ = 13.3 kcal mole
-1
and Δ
S
‡ = 12 cal deg
-1
mole
-1
(3.5
S
fragment). The kinetic observations are consistent with the view that the binding of a single antibody molecule can bring about phage neutralization. There are two ways in which a single antibody molecule can affect neutralization: (1) binding at or near some critical site on the phage may block its function, (2) binding may disturb the general architectural design of the protein shell of the phage. Although the rate of neutralization varied directly with antibody size, consideration of the activation parameters speaks against the dependence of neutralization on simple steric factors. Addition of antibodies directed against rabbit γG-immunoglobulin or the 5
S
pepsin fragment caused approximately a threefold neutralization enhancement. This enhancement may result from the detection of a class of infectious bacteriophage antibody complexes.
Village and Tribal Genetic Distances among American Indians, and the Possible Implications for Human Evolution
Authors: Neel James V. , Ward Richard H.
Published: May 2006

Pair-wise genetic distances based on six genetic systems (Rh, MNSs, Kidd, Duffy, Diego, and haptoglobins) are presented for seven villages of Makiritare Indians, seven villages of Yanomama Indians, and 12 Indian tribes of Central and South America. It is shown that the mean genetic distance between Indian villages is 85-90 per cent of the distance between tribes. Since in the past, the initial event in the formation of a new tribe was probably the breaking away of one or several related villages from an established tribe, it is clear that this initial event could have profound consequences for subsequent tribal gene frequencies. By the criterion of changes in gene frequency in polymorphic genetic systems, the maximal rate of evolution in the American Indian has been approximately 100 times more rapid than the mean rate suggested by calculations based on amino acid substitutions in certain polypeptides of a variety of organisms. The above-mentioned findings could account in part for this 100-fold difference. Some other factors which might diminish the apparent difference between the results of these two types of calculations are mentioned.
Inhibition of Hormone-Sensitive Adenyl Cyclase by Phenothiazines
Authors: Wolff J. , Jones Ann B.
Published: May 2006

Chlorpromazine (3 × 10
-4
M
) prevents the stimulation of adenyl cyclase activity in thyroid membranes produced by thyrotropin and prostaglandin, ACTH stimulation of adenyl cyclase in adrenal tissue, and glucagon- and epinephrine-stimulation of adenyl cyclase activity in liver. Baseline activity is unaffected. Parathyroid hormone stimulation of kidney preparations was not inhibited under these conditions. At chlorpromazine concentrations >3 × 10
-4
M
F
-
-stimulated cyclase activity of thyroid and adrenal tissue was increased. Other phenothiazines, trifluoperazine, and prochlorperazine, have similar effects on thyrotropin and F
-
-stimulated cyclase activity of thyroid. Na
+
- K
+
-dependent ATPase of thyroid is also inhibited by chlorpromazine. Since thymol causes a similar dissociation of hormone- and F
-
-stimulated adenyl cyclase, it is concluded that the surface properties of these agents best account for their effects on adenyl cyclase.
A New Approach to Electromagnetic Blood Flow Determination by Means of Catheter in an External Magnetic Field
Authors: Kolin Alexander
Published: May 2006

Maximal reduction in transverse catheter dimension has been achieved for the purpose of creating an intravascular electromagnetic flow sensor capable of percutaneous introduction into the vascular system. The electrodes are mounted on a flexible frame which collapses as it passes through a small branch blood vessel and expands to span the diameter of the main vascular trunk when entering it. Unlike the catheter flow sensors developed previously, which are velometers, i.e., sensors of fluid velocity, the present one is capable of measuring the volume rate of flow in branch blood vessels as well as in the major sections of the vascular tree. The magnetic field is provided by a large air core electromagnet placed externally to the animal or patient. A special circuit utilizing two electrodes and three leads permits reduction of the unwanted quadrature signal to zero. A standard sine wave electromagnetic flow meter channel designed for use with conventional electromagnetic flow transducers is adequate for flow measurements as well as for power supply to the large magnet. Illustrations of the performance of the apparatus
in vitro
and
in vivo
are presented.
Cellular Sites of Immunologic Unresponsiveness
Authors: Chiller Jacques M. , Habicht Gail S. , Weigle William O.
Published: May 2006

The reconstitution of the immune response of lethally irradiated mice to human γ-globulin is dependent on the synergistic action of bone marrow with thymus cells. Immunologic unresponsiveness appears to involve a functional defect at each of these cellular levels, inasmuch as neither bone marrow nor thymus cells from unresponsive donors are capable of demonstrating synergism in combination with their normal counterpart.
Evolution of the Transcription Unit of Ribosomal RNA
Authors: Perry Robert P. , Cheng Tsai-Ying , Freed Jerome J. , Greenberg Jay R. , Kelley Dawn E. , Tartof Kenneth D.
Published: May 2006

In eukaryotes the two principal RNA components of the ribosomes are initially synthesized as a large complex precursor molecule, which may be thought of as a transcription unit. The precursor is converted, via intermediates, to the mature forms of ribosomal RNA (rRNA). In order to assess the extent of variation in the size of this rRNA transcription unit among different organisms, and to infer its possible mode of evolution, we have determined its molecular weight in several selected species. Pulse-labeled and long-term labeled RNA's were extracted from various types of cells, and analyzed by electrophoresis on acrylamide gels. Identification of particular components as rRNA precursors was made according to several stated criteria. Our results, together with an analysis of previously published data, suggest that in plants and lower animals, up to and including reptiles, the unit of transcription of rRNA is a 2.7-2.8 million dalton molecule, which is only about 25 per cent larger than its combined rRNA products. In contrast, birds, marsupials and placental mammals, exhibit a seemingly less economical form of rRNA synthesis. Their transcription units are 4.0-4.2 million daltons, about 80 per cent larger than the rRNA products. In the organisms with the smaller transcription unit the major intermediate precursor of rRNA is 1.5-1.6 million daltons, as compared to 2.0-2.2 million daltons in birds and mammals. The significance of these findings is discussed in relation to evolutionary changes in the base composition of the ribosomal RNA genes.