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Specific aminoacyl-tRNA's from different mammalian organs and species have been compared by methylated albumin column chromatography. The elution profile of such chromatographs were usually similar, both between tRNA's from different organs in the same animal, and across widely divergent mammalian species. Species differences were found in the elution profile of avian leucyl- and tyrosyl-tRNA's, but not among other tRNA's. In contrast to the similarities of methylated albumin-kieselguhr elution profiles of specific tRNA's from most mammalian organs, the elution profile of Ehrlich ascites tumor cells phenylalanyl-, seryl-, glycyl-and tyrosyl-tRNA differed from normal mouse organ tRNA. An extra peak of tyrosyl-tRNA has also been found in HeLa cells and adeno-7 virus transformed cells, but not in all tumor cells. The tyrosyl-tRNA of mammalian and chick fibroblasts in cell culture, and fibroblasts in the body exhibited a markedly different elution profile from the tyrosyl-tRNA of epithelial cells in culture and of normal organs. The tRNA differences discovered by in vitro charging have all been confirmed in vivo. Possible reasons for these variations are discussed. © 1968.

Tryptophan synthase was purified from Saccharomyces cerevisiae with the aid of affinity chromatography up to a specific activity of 525 units/g protein. Electrophoresis on polyacrylamide gel showed one main protein component. Gel filtration on Sephadex G-150 indicates an average molecluar weight of 143 000. Dissociation with dodecylsulfate followed by dodecylsulfate-acrylamide gel electrophoresis leads to the conclusion that the enzyme is probably composed of four subunits of equal size. The Km-values with respect to its substrates indoleglycerol phosphate, indole and L-serine were estimated. L-Serine was shown to increase the Km-value for indoleglycerol phosphate about 7-fold. Several indole analogues inhibit the tryptophan synthase reaction (B) (i.e. indole + serine → tryptophan); indoleacrylic acid is the most effective. The pH-optimum of tryptophan synthase is around 6.9 to 7.0. Sulfhydryl modification by 5,5'-dithiobis(2-nitrobenzoic acid) and p-chloromercuriphenylsulfonic acid results in a large loss of tryptophan synthase activity, which cannot be prevented by the substrates L-serine and indole. The tryptophan synthase inactivating system from yeast affects the catalysis of both reactions (A) (i.e. indoleglycerol phosphate → indole + glyceraldehyde 3-phosphate) and (B).

1. Rotary shadow-casting of isolated rat liver large ribosomal subunits revealed that 50-70% of these subunits carried one RNase-labile tail with a length of about 50-60 nm. 2. The tail is visible in two types of large ribosomal subunit preparations. (A) In isolated large ribosomal subunits obtained by incubating 77-S run-off ribosomes with 0.5 M KCl. Under these conditions the large subunits have a sedimentation value of 57 S. (B) In preparations of run-off ribosomes which have been converted into 59-S particles after lowering the Mg2+ concentration to 0.5 mM. 3. The 59-S material prepared by simply lowering the Mg2+ concentration represents a mixture of large subunits and dimers of small subunits. 4. In both types of ribosomal subunit preparations large subunits easily change into 48-S or 53-S particles. A reversible conversion between these particles exists depending on the Mg2+ concentration. Moreover, 48-S and 53-S particles dimerize at. lower Mg2+ concentration than the 57-S large ribosomal subunits. 5. A tail has been observed on large subunits of mouse brain, rabbit, reticulocyte, HeLa cell and chick liver ribosomes. They were not present on large ribosomal subunits of Saccharomyces, carlsbergensis, Bacillus licheniformis and Escherichia coli MRE 600. 6. It is postulated that the discrete tail visible in rotary-shadowed rat liver large ribosomal subunits represents the stretched conformation of the protrusion visible in negatively stained particles. [ABSTRACT FROM AUTHOR]

The existence of three stable forms of the 5.8-S ribosomal RNA species in Saccharomyces cerevisiae has been demonstrated. The major form constitutes approximately 90% of the total 5.8-S RNA and the two minor forms each constitute approximately 5%. The nucleotide sequence of the major form begins pA-A-A-Cp. The sequences of the minor forms begin pU-A-U-U-A-A-A-A-A-Cp and pA-U-A-U-U-A-A-A-A-A-Cp. The remainders of the sequence of all three forms appear to be identical. [ABSTRACT FROM AUTHOR]

Saccharomyces cerevisiae and Candida parapsilosis were grown aerobically and micro-aerobically in continuous culture and the energetic efficiency ( Y) and the maintenance energy requirements compared. The bioenergetic parameters were determined using a gas-balance technique, and from cell yield decrements at low dilution rates. The data show that for aerobic cultures, cell yield related to ATP generation ( Y) for the two yeasts is similar and close to the value reported originally by Bauchop and Elsden (1960). However, the efficiency of substrate utilization is greater in the case of C. parapsilosis since the apparent P/O value under aerobic conditions is 1.8 as compared to about 1 for S. cerevisiae. The maintenance energy coefficients based on ATP requirement for aerobic cultures of both yeast were greater than the corresponding values for micro-aerobic cultures; similarly cultures of a petite mutant of S. cerevisiae had a lower maintenance energy requirement than comparable aerobic wild-type cultures. It is suggested that these differences may reflect the energy requirement for the upkeep of a greater degree of functional complexity in aerobic, wild-type cells, as compared with micro-aerobic or respiratory deficient cells. [ABSTRACT FROM AUTHOR]

We have already described that α hormone excreted by α type cells expands cells of α type specifically and α hormone excreted by α type cells expands α type cells in Saccharomyces terevisiae. Both substances are steroidal compounds. In the present experiment the third hormonal substance has been found. a Hormone induced excretion of a methylene chloride‐insoluble substance which expands a type cells specifically, when added to a type cells. Testosterone showed the same type of action as that of a hormone. On the other hand, a hormone did not show an action to induce excretion of methylene chloride‐insoluble hormonal substance, when added to a type cells. Relation among three hormonal substances described above seems to be important to make clear the mating process of the yeast.

A procedure for subjecting cells of Saccharomyces chevalieri to "osmotic shock" is described. Exponentially growing yeast cells are first suspended in a concentrated solution of mannitol plus EDTA, 2-mercaptoethanol and Tris. After this high osmotic treatment, the cells collected by centrifugation are suddenly resuspended in a solution of MgCl2 of low osmotic strength. This treatment causes the rapid and specific release of extracellular enzymes from yeast cells, namely invertase, a Co2+ activated 5′-nucleotidase, acid phosphatase and alkaline pyrophosphatase. Also, the capacity to accumulate L-proline is greatly diminished. At the same time, some material absorbing at 260 nm and 7% of the cell wall protein are released into the shock medium Alkaline pyrophosphatase and 5′-nucleotidase are described for the first time as extracellular enzymes for yeast. Intracellular yeast enzymes such as alcohol dehydrogenase, alkaline phosphatase and cyto-chrome-c oxidase remain within the cell after "osmotic shock". The viability of yeast cells in 80 % after being subjected to the "osmotic shock" procedure. Examination of yeast cells in the electron microscope shows that a hairy-like structure in the external portion of the cell wall is practically lost after the osmotic shock treatment. No other difference between shocked and unshocked cells can be visualized. [ABSTRACT FROM AUTHOR]

The β-D-fructofuranoside fructohydrolases (invertases) of Saccharomyces under the control of the non-allelic genes SU-1, SU-2, SU-3, SU-4, and SU-5 have been examined with respect to the effect of pH on the Michaelis constants and maximum velocities of their hydrolysis of sucrose.
In every case, the two molecular forms of each invertase (the large extracellular form and the small intracellular form) appeared to be identical as far as the reaction kinetics, but between the different, invertases both similarities and differences exist. If quasi-equilibrium is assumed to be operative, the reaction of all the invertases fits a model according to which the enzyme-substrate complexes of all five invertases behave, kinetically, in identical manner. The unsubstrated enzymes, on the other hand, show small but definite differences: SU-1 and SU-4 invertases and SU-2, SU-3 and SU-5 invertases form two groups within which the enzymes respond m essentially identical manner to variations in the environmental pH. SU-2 invertase can be separated from the second group as it is unique among the five invertases studied in being inhibited by dianisidine. [ABSTRACT FROM AUTHOR]

The concentrations of glycolysis intermediates, citric acid and adenine nucleotides were measured in resting cells of Saccharomyces cerevisiae during aerobic glucose metabolism. Addition of glucose resulted in a decrease in the intracellular content of phosphoglyceric acids and phosphoenolpyruvate. As extracellular glucose became depleted the level of these intermediates increased. Thus changes in theft intracellular content were regulated by factors other than the supply of extracellular substrate. Cross-over behaviour of phosphoenolpyruvate and pryruvic acid together with the inverse relationship which existed between the concentration of phosphoenolpyruvate and the rate of the pyruvate kinase reaction, indicated that regulatory changes in the activity of pyruvate kinase occurred. These activity changes were compared with those of the intracellular content of reposed in vitro effectors of the enzyme: fructose 1,6-diphosphate, citric acid, ATP and ADP. ATP and ADP did not appear to be involved in regulating changes in the activity of the enzyme. Although citric acid may have contributed towards some of the changes in enzyme activity, fructose 1,6-diphosphate appeared to be the primary relator, under the conditions of these experiments. Comparison of the results with the properties reported for the isolated enzyme, suggested that, in vivo, fructose 1,6-diphosphate affects the affinity of pyruvate kinase for phosphoenolpyruvate. This, in turn, appears to regulate the intracellular content of phosphoenolpyruvate and phosphoglyceric acids. The significance of the results is discussed in relation to both glycolysis and gluconeogenesis. [ABSTRACT FROM AUTHOR]

With mitochondria from Saccharomyces carlsbergensis the functional relationship of the exogenous and endogenous NAD system has been investigated with respect to the membrane barrier, the localisation of NADH dehydrogenase and other NAD- and flavine-linked dehydrogen- ases. 1. Added NAD and NADH do not permeate through the inner membrane into the matrix space of mitochondria from S. carlsbergensis despite the high rate of oxidation. There is no exchange between exogenous and endogenous NADH and NAD. 2. A transhydrogenation between external and internal NADH and NAD across the inner membrane is not observed. 3. By applying the "ferricyanide method" two separate dehydrogenases can be identified: one for the oxidation of exogenous NADH, located towards the outer surface of the inner mitochondrial membrane; and a second for the oxidation of endogenous NADH directed towards the inner surface. Both dehydrogenases are connected to the cytochrome chain through the ubiquinone pool. 4. About 50% of the total NADH dehydrogenase activity of yeast mitochondria is solubilized by sonication. The solubilized NADH dehydrogenase is tentatively identified with the external enzyme. This agrees with the finding that on opening the membrane by sonication the total activity of NADH-ferricyanide reduction increases by 65%. 5. Applying both [4B-³H]NADH and [4A-³H]NADH the oxidation of both exogenous and endogenous NADH by ferricyanide and by oxygen are found to be B-specific. 6. By application of the "ferricyanide method" to other substrates it is concluded that the dehydrogenases for glycerolphosphate and possibly lactate are located before the barrier for ferricyanide while the dehydrogenases for ethanol, isocitrate and succinate are localized behind it. This barrier is identical with the inner mitochondrial membrane. 7. The existence ora mitochondrial alcohol dehydrogenase, accounting for about 6% of the total cellular activity and located in the matrix space, is established. The dual localization of alcohol dehydrogenase is considered to facilitate the equilibration between the intra-and extramitochondrial NAD systems via an ethanol-acetaldehyde shuttle. [ABSTRACT FROM AUTHOR]

An isoleucine requiring mutant (M6) of Saccharomyces cerevisiae was found to have an altered threonine deaminase. The mutation maps in the is1 locus which corresponds to a threonine de- aminase deficiency in other isoleucine requiring mutants. Both the molecular weight and the absolute number of sites for the ligands remain the same in the wild type and the mutant enzyme. The following catalytic and regulatory properties are modified in the mutant enzyme: 1. Affinity towards threonine is 4 to 6 fold lower. Also, in contrast with the wild type, co-operativity between substrate molecules is maintained at pH 7.5. 2. Affinity towards the substrate analogue (competitive inhibitor), allothreonine, is 2 to 3 fold lower. 3. Affinity towards a feedback inhibitor, isoleucine, is increased by 5 to 6 fold. 4. Valine remains active as a positive effector (suppressing the cooperativity between substrate molecules) but a 20 fold higher concentration is required for a 500/0 maximal effect, On the other hand, at high concentrations, valine is inhibitory. The apparent Ki, at substrate saturation, is 38 mM. The changes in kinetic properties of the mutant enzyme, which occurred for each individual ligand in the most unfavorable direction, can explain its complete inefficiency in vivo, and account for the isoleucine requirement of the mutant strain. Growth studies have shown that the impaired enzyme can, in viva, utilize exogenous threonine and be activated by exogenously supplied value, These results have been interpreted as an indication that endogenous threonine and valine concentrations were the factors responsible for the mutant inability to grow m minimal medium. In addition to explaining the physiological behavior of the mutant M 6, the present study contributes information on the interdependence between various ligand sites on the yeast threonine deaminase. [ABSTRACT FROM AUTHOR]

The regulation of the enzymes involved in the operation of the glyoxylate cycle was studied in the yeast Saccharomyces cerevisiae. All enzymes showed an increase in specific activity under growth conditions where the glyoxylate cycle is needed as an anaplerotic pathway. In the presence of 1% glucose, the synthesis of all enzymes, excepts fumarase, was repressed. However, appreciable activities of citrate synthase, aconitase, fumarase, and malate dehydrogenase were found in the cytoplasm. The significance of these observations for the operation of the glyoxylate cylcele is discussed. [ABSTRACT FROM AUTHOR]

Partial purification of transfer RNA-methylating enzymes from Saccharomyces cerevisiae D84 yielded eight different enzyme fractions, the properties of which have been studied. All of these enzymes also showed some activity with ribosomal RNA from Escherichia coli. The enzymes were found to differ in their species specificity. One of the enzyme fractions is highly active with Aerobacter aerogenes tRNA, foxing N²-dimethylguanine, but inactive with wheat germ tRNA. Other fractions are active with wheat germ tRNA, synthesizing 5-methyluracil only. Chromatography on hydroxylapatite resulted in three different fractions containing activity for the formation of 5-methyluracil in tRNA from E. coli. Although the same methylated base is formed, these enzymes differ in their speciticities. [ABSTRACT FROM AUTHOR]

Fractionation of enzymes, which catalyze the transfer of methyl groups from S-adenosyl-Lmethionine to transfer RNA, from extracts of Saccharomyces cerevisiae has yielded eight separate methylating fractions. The products of methylation were identified by thin-layer chromatography of acid hydrolyzed tRNA with known reference compounds. Enzyme activities for synthesis of four methylated guanines, 1-methyladenine, 5-methylcytosine and thymine have been demonstrated. Three of the enzyme fractions produced thymine, apparently free of other methylating activity. Some fractions also contained enzymatic activity for formation of a heterogeneous group of compounds resistent to acid hydrolysis, probably related to ribose-methylated dinucleotides. [ABSTRACT FROM AUTHOR]

Extracts from yeast cells grown under different conditions and from mitochondria were subjected to agar gel electrophoresis. Three bands showing malate dehydrogenase activity were found in extracts from aerobic derepressed cells (c-MDH I, c-MDH II, and m-MDH III), whereas generally only one band was present in extracts from anaerobic repressed cells (c-MDH I) and another one m extracts from mitochondria (m-MDH III) of aerobic derepressed cells. The different malate dehydrogenases showed dissimilar regulatory and physical properties, e g. sensitivity to inactivation by heat, inhibition by oxaloacetate and by p-chloromercuri-benzoate, activation by P1, Michaelis constants etc. A separation of malate dehydrogenases by DEAE-cellulose chromatography was performed giving only two malate dehydrogenase forms. These two forms were subjected to agar gel electrophoresis and gave one band each, corresponding to the cytoplasmic c-MD I and c-MDH II. The possible metabolic significance of the three malate dehydrogenase isoenzymes is discussed. [ABSTRACT FROM AUTHOR]

A study of threonine deaminase from Saccharomyces cerevisiae has been undertaken. The enzyme has been purified 50-fold, with a low resolution of pyridoxal phosphate coenzyme. The purified enzyme is very unstable under all conditions tried so far. Properties have been studied with crude extracts. Optimum pH has been found to be 8.2. Isoleucine has complex effects on the enzyme activity. At a concentration of 0.1 mM, it is able to stimulate the enzyme. At higher concentrations, isoleucine inhibits. The Ki values increase with increasing pH, but 100% inhibition can be reached at all ranges of pH studied. Affinity of the enzyme for its substrate is even more strongly modified by pH. a) Substrate cooperativity, nil at pH 7, intermediate at pH 8, seems to be maximum at pH 9. At any pH, the substrate cooperativity can be suppressed by addition of L-valine. In addition, rather low concentrations of isoleucine also act partly as valine does. b) Apparent Km values, measured in the presence of valine, vary with pH in the opposite direction to Ki values. Hill's coefficients for substrate and inhibitor reflect these findings. For threonine alone, they vary from 1.2 at pH 7 to 3 at pH 9, In the presence of valine, they remain close to 1, at all pH. Isoleucine, 0.1 mM, produces an incomplete effect compared to valine. For isoleucine inhibition, the cooperativity coefficients remain close to 3 at all pH. The molecular weight of the enzyme has been determined to be roughly 1.2 × 105, at, pH 6.8 and at pH 8.7. Thermal inactivation is unimodal and fails to show desensitization of the enzyme in any of the conditions tried. The implications of these results on the structure of the enzyme have been discussed. [ABSTRACT FROM AUTHOR]

The methylation sites and the number of methyl groups of 26-S and 17-S ribosomal RNA (rRNA) of Saccharomyces carlsbergensis were investigated. 26-S and 17-S rRNA contain 43 and 24 methyl groups per molecule, respectively, of which in both molecules 6 are attached to the heterocyclic bases. In 26-S rRNA the base-methyl groups are present as two copies of m³U, m5C as well as m¹A, whereas the methylated bases in 17-SrRNA are one mTG, one methylated cytidine and two of m26A. In 17-S rRNA there are 11 different alkali-stable (i.e. ribose-methylated) dinucleotides, while 26-S rRNA contains 15 different alkali-stable dinucleotides, and in addition 4 alkali-stable trinucleotides (Am-Cm-Gp, Am-Gm-Cp, Am-Am-Up and Um-Gm-ψp). Most of the methylated oligonucleotides found in a ribonuclease T1 digest of 26-S or 17-S rRNA occur in approximately one-molar amounts. The combined data suggest that yeast ribosomal RNA is essentially homogeneous in its methylated sequences and in addition that the methylation is a highly specific process. [ABSTRACT FROM AUTHOR]

Among 52 Saccharomyces cerevisiae fatty acid synthetase (fas)mutants screened for their ability to incorporate 14C-labeled pantothenic acid into the fatty acid synthetase multienzyme complex, especially those of fas-complementation group VII had lost this ability. The purified fatty acid synthetase complexes of all the 19 fas-mutants available from this group were shown to be free of 14C-labeled pantothenic acid. The amount of pantothenate incorporated into the enzymes of several other fas-mutants of the non-pleiotropic complementation groups II, V, VI and VIII, however, was similar to that observed with wild-type fatty acid synthetase. The purified pantothenate-free fatty acid synthetases of five different group VII fas-mutants have been tested for the seven known component enzymes of the complex. In all mutants, only the β-ketoacyl synthetase was inactive whereas in vitro all the other partial activities were unimpaired. By sodium dodecylsulfate-polyacrylamide-gel electeophoresis, no differences could be observed between the protein structure of the pantothenate-free mutant fatty acid synthetase and that of the wild-type comp ex. Both were separated into three different components A, B and C with molecular weights of 185000, 180000 and 177000, respectively. However, some fas-mutants consist only of the components A and B, others only of B and C. The study of various [14C]pantothenate-labeled mutant fatty acid synthetases suggests that component C originates from A presumably by limited proteolysis. In the undegraded complex AB, [14C]pantothenate is only associated with the component A. Since in one of the mutants studied A is completely converted to C, it is concluded that A is one distinct component rather than a group of components with identical molecular weights. It is tentatively suggested that the gene product of fas 2, one of the two known fatty-acid-synthetase gene clusters in yeast, is only one, single and multifunctional polypeptide chain. Therefore, it appears that in yeast, the acyl carrier protein is not an individual protein component of the fatty acid synthetase complex, but only a distinct region of the multifunctional polypeptide chain encoded by fas 2. [ABSTRACT FROM AUTHOR]

A mutant of Saccharomyces cerevisiae has been selected which has temperature-sensitive mitochondrial protein synthesis. This has been demonstrated by incorporation into cycloheximide-inhibited whole cells, isolated mitochondria and hybrid cell-free systems. The temperature sensitivity is associated with the mitochondrial ribosomes and the mutation is recessive and nuclear. [ABSTRACT FROM AUTHOR]

The activities of the enzymes ornithine transaminase in Saccharomyces cerevisiae and β-galactosidase in Saccharomyces lactis increase periodically once per cell cycle. This step synthesis of the enzymes is observed under either basal or induced conditions; however, when the cells are growing under non-induced conditions, addition of the inducer at any stage of the ceil cycle results in an enhancement of the enzyme activity for both enzymes. The amount of enzyme activity induced is constant for much of the cell cycle but doubles over a portion of the cycle, probably as a result of replication of the structural gene of these enzymes during the S phase. These results suggest that whereas there is periodic expression of structural genes during the cell cycle of yeasts grown in a constant environment, these genes can, upon induction, be expressed at any time during the cell cycle. [ABSTRACT FROM AUTHOR]

A series of 62 mutants of Saccharomyces cerevisiae showing high levels of resistance to oligomycin and rutamycin have been isolated. These mutants can be subdivided into two classes on the basis of their cross resistance to a variety of inhibitors and uncouplers of mitochondrial energy-conservation reactions. Class I mutants show cross resistance to aurovertin, triethyltin, ‘1799’ (a hexafluorotriacetone derivative), uncoupling agents and inhibitors of mitochondrial protein synthesis such as chloramphenicol, mikamycin and spiramycin. Class II mutants are specifically resistant to oligomycin and rutamycin and show no cross resistance to aurovertin, triethyltin or any of the other agents tested. The majority of the class I mutants and one of the class II mutants exhibit cold sensitivity of the ohgomycin resistance, i.e. they lose resistance at the non-permissive temperature of 20 °C, and this provides a further basis for classification of the mutants. The growth rates of the majority of these resistant mutants from both classes were unaltered from the wild type and the growth yield of the class II mutants was also the same as that of the parental strains. The growth yield of the class I mutants, however, was 15–20% less than that of the wild type. No differences in mitochondrial morphology or of the number of mitochondria per cell were seen on examination by the electron microscope. The isolation and properties of specific mitochondrial oligomycin-resistant mutants supports the biochemical evidence for different sites of action of oligomycin, triethyltin and uncoupling agents on energy-conservation reactions. [ABSTRACT FROM AUTHOR]

The molecular weights of yeast L-Iactate dehydrogenase (cytochrome b2) and of its polypeptide chains have been measured by ultracentrifugation. The intact protein was found to have a molecular weight of 240000 ± 10000 by sedimentation equilibrium measurements according to the Yphantis high-speed method. The solution obtained by dissolving the protein in 6 M guanidine (with added 2-mercaptoethanol) behaved as if it were monodisperse, giving Mr = 31300 ± 2000, by approach-to-equilibrium measurements. This result indicates that the "58600 unit" associated to one set of prosthetic groups, heme and flavin, is made up of two chains, and thus the whole molecule contains a total of eight chains, identical or not. However, as the viscosity of the medium was reduced (using 2 M guanidine) the paucidispersity of the cytochrome b2 solution was revealed. The mixture was shown to consist of two kinds of chains distinct in molecular weight. From these experiments the molecular weight of the light chain was found to be 22600 ± 1500. After partial separation of the two chains by gel filtration through Sephadex G-100, the molecular weight of the heavy chain was estimated as 39700 ± 3000. Preliminary experiments indicate that the heavy component can bind quantitatively the heme prosthetic group. The FMN appears to be bound to the light component. [ABSTRACT FROM AUTHOR]

The subunit structure of cytochrome b2 prepared from the yeast Hansenula anomala has been studied and compared to known data concerning the homologous enzyme prepared from ordinary bakers' yeast Saccharomyces cerevisiae. By high-speed equilibrium ultracentrifugation, the molecular weight has been determined as 236 000 ± 10 000, while subunits of 58 000 ± 5000 are observed either m 6 M guanidine under reducing conditions or in 0.01 M phosphate. By electrophoresin in 6 M urea as well as in dodecylsulfate-mercaptoethanol, this subunit behaves as a single component. In crystalline enzyme preparations from bakers' yeast, the same unit is known to be made up of two chains of about 21 000 and 36 000 molecular weight. The hypothesis that an artificial proteolytic cleavage is responsible for the observed two-chain pattern with the Saccharomyces enzyme is proposed. Experimental evidence for this hypothesis is given in the following paper. [ABSTRACT FROM AUTHOR]

The article presents a study examining Monilia and other similar organisms found within the oral cavity. Organisms beside the Moniliae examined within the article include Endomyces, Cryptococci, and Saccharomyces. The characteristics of Monilia are also noted, mentioning that it is a yeastlike organism that lacks ascospores, reproduces by budding, and develops mycelia under certain conditions.

The subunit structure of cytochrome b2 prepared from the yeast Hansenula anomala has been studied and compared to known data concerning the homologous enzyme prepared from ordinary bakers' yeast Saccharomyces cerevisiae. By high-speed equilibrium ultracentrifugation, the molecular weight has been determined as 236 000 ± 10 000, while subunits of 58 000 ± 5000 are observed either m 6 M guanidine under reducing conditions or in 0.01 M phosphate. By electrophoresin in 6 M urea as well as in dodecylsulfate-mercaptoethanol, this subunit behaves as a single component. In crystalline enzyme preparations from bakers' yeast, the same unit is known to be made up of two chains of about 21 000 and 36 000 molecular weight. The hypothesis that an artificial proteolytic cleavage is responsible for the observed two-chain pattern with the Saccharomyces enzyme is proposed. Experimental evidence for this hypothesis is given in the following paper. [ABSTRACT FROM AUTHOR]

Studies of the toxicity of 2,4,5,6-tetrachloroisophthalonitrile (TCIN) to cells of Saccharomyces pastorianus and Neurospora crassa showed that 2 to 4 μg/ml of the toxicant were required to inhibit growth. Several thiol compounds reversed toxicity to growth. Glucose oxidation was severely impaired in treated cells of both test organisms. The toxicant at 2 or 4 μg/ml markedly reduced soluble thiol content of these cells. Bound thiol content was less affected in S. pastorianus cells than soluble thiol content. Uptake of toxicant by yeast cells was accompanied by formation of derivatives, some of which resembled those formed by reaction of glutathione with TCIN in vitro. Coenzyme A, glutathione, and 2-mercaptoethanol readily formed derivatives with TCIN in vitro. The nature of these derivatives was studied using 2-mercaptoethanol products as model substituents. Four derivatives were formed with 2-mercaptoethanol each with similar functional groups but showing dissimilar degrees of mobility during silica gel chromatography. Evidence indicated that these are derivatives of TCIN in which 1 to 4 of the halogens has been substituted by 2-mercaptoethanol. The mechanism of fungicidal action of TCIN is attributed to thiol inactivation. [ABSTRACT FROM AUTHOR]

Effect of auxin and gibberellic acid on sporulation of a yeast, Saccharomyces ellipsoideus, was studied. When added to the sporulation media, gibberellic acid promoted sporulation. The sporulation rate was higher in the medium SGV with vitamins than in the vitamin-free SG, but the effect of gibberellic acid was more pronounced in the latter. Auxin (IAA, 2,4-D, and NAA) inhibited sporulation in SGV, but promoted it in SG. This sporulation-promoting effect of IAA was reversed by an antiauxin, 2,4,6-T. Preculturing in the presence of added IAA increased sporulation. Added to the preculture medium, gibberellic acid alone showed little effect on sporulation, but in combination with IAA it enhanced sporulation conspicuously. IAA and gibberellic acid were effective in sporulation promotion only when added before the nuclear enlargement occurred in sporulation culture. [ABSTRACT FROM AUTHOR]

1. After growth in a zinc- and calcium-containing inorganic nitrogen medium, the respiratory gas exchange of Saccharomyces pastorianus greatly exceeded the value of the control. 2. addition of zinc alone to the inorganic nitrogen medium in a concentration of 0.07 ppm resulted in both reduced gas exchange and increased RQ. 3. After growth in organic nitrogen media only quantitative differences in the respiration rate were found. 4. Endogenous respiration was only quantitatively influenced by the previous growth conditions. [ABSTRACT FROM AUTHOR]

Calcium has a striking effect on the growth of S. pastorianus when ammonium salts are given as the nitrogen source, provided the medium contains small amounts of zinc. Zinc or calcium given separately do not increase growth above the control. The minimum concentrations of calcium and zinc necessary for obtaining maximal growth were 0.05 ppm of Zn2+ and 12 ppm of Ca2+. The growth increasing effect appears as a higher rate of multiplication of cells. When organic nitrogen sources are given to the yeast, zinc has to be added to obtain maximal growth. Addition of calcium is here of little importance. [ABSTRACT FROM AUTHOR]

The article discusses research on the association of dental caries with the amino-acid requirements of acidogenic microorganisms in the mouth. The research method for preparing cultures of Lactobacillus acidophilus, Streptococcus salivarius, Staphylococcus albus, and Saccharomyces is mentioned. Data is provided which shows the effect of deleted amino acids on acid production in the microorganisms.