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T Kamiryo

Publications and source records attributed to T Kamiryo.

At least 73 records · Page 4Linked to original sources
PubMed1980

Cell-free translation and regulation of Candida lipolytica acetyl-coenzyme-A carboxylase messenger RNA.

Messenger RNA from Candida lipolytica directs the synthesis of complete acetyl-coenzyme-A carboxylase in the mRNA-dependent reticulocyte lysate cell-free translation system. The identity of the translation product is evidenced by the following results: first, it is immunoprecipitated with antibody to acetyl-CoA carboxylase and competes with authentic acetyl-CoA carboxylase for binding to the antibody; secondly, it co-migrates with authentic acetyl-CoA carboxylase (Mr 230000) upon dodecylsulfate/polyacrylamide gel electrophoresis; finally, the peptide fragments formed by its partial proteolysis with papain or alpha-chymotrypsin are identical with those formed from authentic acetyl-CoA carboxylase. With the use of this assay system, it has been demonstrated that the level of acetyl-CoA carboxylase mRNA activity in C. lipolytica cells decreases with increasing concentrations of oleic acid in culture medium and that the changes in the mRNA activity parallel those in the cellular level of acetyl-CoA carboxylase. This finding, in conjunction with our previous study, indicates that the diminished synthesis of acetyl-CoA carboxylase in cells grown in the presence of fatty acid is due to a reduced level of the mRNA coding for the enzyme.

Acetyl-CoA Carboxylase↗
PubMed1979

Acyl-coenzyme-A synthetase I from Candida lipolytica. Purification, properties and immunochemical studies.

Acyl-coenzyme-A synthetase I from Candida lipolytica has been purified to homogeneity as evidenced by polyacrylamide gel electrophoresis in the presence and absence of dodecylsulfate as well as by Ouchterlony double-diffusion analysis. The purification procedure involves resolution of cellular particles with Triton X-100 and chromatography on phosphocellulose, Blue-Sepharose and Sephadex G-100. The purified enzyme exhibits a specific activity of 20--24 U/mg protein at 25 degree C, which is about 100-fold higher than those of long-chain acyl-CoA synthetases hitherto reported. The molecular weight of the enzyme has been estimated by polyacrylamide gel electrophoresis in the presence of dodecylsulfate to be approximately 84 000. The enzyme is specific for fatty acids with 14--18 carbon atoms regardless of the degree of unsaturation. Studies with the use of specific antibody to acyl-CoA synthetase I have indicated that this enzyme is immunochemically distinguishable from acyl-CoA synthetase II.

Candida↗
PubMed1979

Involvement of long-chain acyl coenzyme A for lipid synthesis in repression of acetyl-coenzyme A carboxylase in Candida lipolytica.

Mutant strains of Candida lipolytica defective in acyl-CoA synthetase II [acid:CoA ligase (AMP-forming), EC 6.2.1.3] have been isolated. The mutants fail to grow on fatty acid as a sole carbon source but are capable of incorporating exogenous fatty acid into cellular lipids. This observation, together with our previous finding that mutant strains defective in acyl-CoA synthetase I cannot incorporate exogenous fatty acid into cellular lipids but are able to degrade fatty acid via beta-oxidation, indicates the presence of two functionally distinct long-chain acyl-CoA pools in the cell--i.e., one for lipid synthesis and the other for beta-oxidation. Unlike the wild-type and the revertant strains as well as the mutants lacking acyl-CoA synthetase II, the mutants defective in acyl-CoA synthetase I do not exhibit the repression of acetyl-CoA carboxylase [acetyl-CoA:carbon-dioxide ligase (ADP-forming), EC 6.4.1.2] by exogenous fatty acid. Measurement of the two long-chain acyl-CoA pools with the aid of appropriate mutant strains has indicated that the long-chain acyl-CoA to be utilized for lipid synthesis, but not that to be degraded via beta-oxidation, is involved in the repression of acetyl-CoA carboxylase.

Acetyl-CoA Carboxylase↗
PubMed1978

Subcellular localization of two long-chain acyl-coenzyme-A synthetases in Candida lipolytica.

Studies have been made on the subcellular localization of two long-chain acyl-coenzyme-A synthetases as well as glycerolphosphate acyltransferase and the acyl-CoA-oxidizing system in Candida lipolytica grown on oleic acid. Acyl-CoA synthetase I is distributed among different subcellular fractions, including microsomes and mitochondria where glycerolphosphate acyltransferase is located. On the other hand, acyl-CoA synthetase II is localized in microbodies where the acyl-CoA-oxidizing system is located. These results support our previous conclusion that acyl-CoA synthetase I is responsible for the production of acyl-CoA to be utilized for the synthesis of cellular lipids, while acyl-CoA synthetase II provides acyl-CoA that is exclusively degraded via beta-oxidation.

Candida↗
PubMed1977

Candida lipolytica mutants defective in an acyl-coenzyme A synthetase: isolation and fatty acid metabolism.

Mutant strains of Candida lipolytica defective in an acyl-CoA synthetase [acid:CoA ligase (AMP-forming); EC 6.2.1.3]were isolated. The mutant strains apparently exhibited no acyl-CoA synthetase activity in vitro and were, in contrast to the wild-type strain, incapable of growing in the presence of exogenous fatty acid when cellular synthesis de novo of fatty acid was blocked. However, the mutant strains grew on either fatty acid or n-alkane as a sole carbon source at rates comparable to that observed for the wild-type strain. Analysis of the fatty acid composition of the lipids from the mutant cells grown on odd-chain-length fatty acid as well as [14C]oleic acid incorporation studies have shown that the mutant cells, unlike the wild-type cells, cannot incorporate exogenous fatty acid as a whole into cellular lipids, but utilize the fatty acid that is synthesized de novo from acetyl-CoA produced by degradation of exogenous fatty acid. This finding indicates the presence of at least two acyl-CoA synthetases that activate long-chain fatty acid. One, designated acyl-CoA synthetase I, which is absent in the mutant strains, is responsible for the production of acyl-CoA to be utilized for the synthesis of cellular lipids. The other acyl-CoA synthetase provides actyl-CoA that is exclusively degraded via beta-oxidation to yield acetyl-CoA.

Candida↗
PubMed1976

Evidence that acyl coenzyme A synthetase activity is required for repression of yeast acetyl coenzyme A carboxylase by exogenous fatty acids.

The cellular content of acetyl-CoA carboxylase [acetyl-CoA:carbon-dioxide ligase (ADP-forming), EC 6.4.1.2] in Saccharomyces cerevisiae is reduced by the addition of long-chain fatty acids to the culture medium. Mutant strains of S. cerevisiae defective in acyl-CoA synthetase [acid:CoA ligase (AMP-forming), EC 6.2.1.3] were isolated and used to determine whether fatty acid itself or a metabolite of fatty acid is more directly responsible for the repression of acetyl-CoA carboxylase. Cells of the mutant strains were capable of incorporating fatty acid to an extent comparable to that observed with the wild-type strain, but they accumulated markedly more of the incorporated fatty acid in the nonesterified form than did the wild-type cells. The level of acetyl-CoA carboxylase activity in the mutants, in contrast to that in the wild-type strain, was hardly affected by the addition of fatty acids to the medium. These results indicate that the activation of exogenous fatty acid is required for the repression of acetyl-CoA carboxylase, supporting the view that the repressive effect is mediated by some compound metabolically derived from fatty acid.

Acetate-CoA Ligase↗
PubMed1976

Acetyl-coenzyme-A carboxylase of Candida Lipolytica. 1. Purification and properties of the enzyme.

Acetyl-coenzyme-A carboxylase has been isolated in homogeneous form from Candida lipolytica. The homogeneity of the enzyme preparation is evidenced by analytical ultracentrifugation, dodecyl-sulfate-polyacrylamide gel electrophoresis and Ouchterlony double-diffusion analysis. The purified enzyme exhibits a specific activity of 8.0 U/mg protein at 25 degrees C and contains 1 mol biotin/263000 g protein. The sedimentation coefficient (S20,W) of the enzyme is 18 S. It has been shown by dodecyl-sulfate-polyacrylamide gel electrophoresis that the enzyme possesses only one kind of subunit with a molecular weight of 230000. This finding, together with the biotin content, indicates that the C. lipolytica enzyme has a highly integrated subunit structure. The C. lipolytica enzyme is very labile, but is stabilized by glycerol. The enzyme is markedly activated by poly(ethyleneglycol), the activation being due principally to a decrease in the Km values for substrates. Even in the presence of this activator, the Km value for acetyl-CoA of the C. lipolytica enzyme is much higher than that of the enzyme from Saccharomyces cerevisiae and animal tissues. The C. lipolytica enzyme, unlike the enzyme from animal tissues, is not activated by citrate.

Acetyl-CoA Carboxylase↗
PubMed1976

Acetyl-coenzyme-A carboxylase of Candida lipolytica. 2. Regulation of cellular content and synthesis of the enzyme.

The level of acetyl-coenzyme-A carboxylase activity in Candida lipolytica undergoes large variations depending upon the carbon source on which the yeast is grown. Cells grown on n-alkanes or fatty acids exhibit a lower activity level than do cells grown on glucose. Among the n-alkanes and fatty acids tested, n-heptadecane, n-octadecane, oleic acid and linoleic acid reduce the enzyme activity to the lowest levels, which are 16-18% of the activity level in glucose-grown cells. Immunochemical titrations and Ouchterlony double-diffusion analysis with specific antibody as well as kinetic studies have indicated that the observed decrease in the level of acetyl-CoA carboxylase activity is due to a reduction in the cellular content of the enzyme. Furthermore, isotopic leucine incorporation studies with the use of the immunoprecipitation technique have demonstrated that the relative rate of synthesis of the enzyme in oleic-acid-grown cells is diminished to 12% of that in glucose-grown cells. Evidence has also been obtained to support the view that the enzyme in this yeast is not degraded at a rate high enough to contribute to the marked decrease in the cellular content of the enzyme. Thus, it is concluded that the reduction in acetyl-CoA carboxylase content in fatty-acid-grown cells is due to diminished synthesis of the enzyme.

Acetyl-CoA Carboxylase↗
PubMed1974

Penicillin-resistant temperature-sensitive mutants of Escherichia coli which synthesize hypo- or hyper-cross-linked peptidoglycan.

A group of Escherichia coli mutants which are ampicillin resistant at 32 C and which either are unable to grow or lyse at 42 C has been selected. These mutants have been classified by a number of characteristics: total peptidoglycan synthesis measured by [(14)C]diaminopimelic acid incorporation, extent of cross-linking of the peptidoglycan which is synthesized, growth characteristics at the two temperatures, and morphology. Two especially interesting groups of mutants have been described. In one of these, a hypo-cross-linked peptidoglycan was synthesized at the nonpermissive temperature. Most of these organisms lysed at 42 C. In another group, the peptidoglycan synthesized at 42 C was hyper-cross-linked. Many of these organisms were spherical. Studies of revertants indicated that ampicillin resistance, temperature sensitivity, cross-linking, growth characteristics, and morphological changes may be related to a single mutational event in both of these groups.

Ampicillin↗
PubMed1974

Mechanism of action and development of resistance to a new amidino penicillin.

The mechanism of killing of Escherichia coli by a novel beta-lactam antibiotic, an amidino penicillin, has been investigated. This compound converts E. coli to relatively stable spherical forms at low concentration. However, the amidino penicillin caused no alteration in any of those parameters of peptidoglycan synthesis which can be studied. Above 10 mug of the antibiotic per ml the cells began to lyse, and a second mode of killing appeared. Mutants resistant to the amidino penicillin were isolated and several were studied in detail. Three mutant phenotypes were distinguished: (i) spherical shape and hypersensitive to lysis by either amidino penicillin or ampicillin; (ii) spherical shape and normally sensitive to lysis; (iii) rod shape, converted to viable spheres by amidino penicillin and normally sensitive to lysis.

Amidines↗
PubMedDate not supplied

Stereotactic frame-based error in magnetic-resonance-guided stereotactic procedures: a method for measurement of error and standardization of technique.

When using the stereotactic Leksell G frame for magnetic-resonance-based functional stereotactic lesions, the authors occasionally encountered a situation in which it was not possible to apply the anterior plate of the coordinate box successfully because it came into contact with the anterior posts of the frame; it was noted that the posts as well as the base ring became distorted by the force required to insert the cranial fixation pins. To examine this issue, measurements were taken of the amount of distortion relative to the torque on the screws. It was also found that backward movement of the posterior segment of the base ring indirectly narrowed the anterior spaces for plate insertion. A determination was made that torque over 6 inch pounds caused undesirable contact between the posts and the coordinate box.

Equipment Design↗