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K B Jacobson

Publications and source records attributed to K B Jacobson.

104 records · Page 6Linked to original sources
PubMed1969

Multiple phenylalanyl-transfer ribonucleic acid synthetase activities in the cytoplasm of Neurospora crassa.

Several tRNA's specific for a particular amino acid have been shown to exist in multiple, or isoaccepting, forms. There is considerable interest in establishing whether multiple aminoacyl-tRNA synthetases also exist. We present evidence that the cytoplasm of Neurospora crassa contains three chromatographically separable phenylalanyl-tRNA synthetases distinct from mitochondrial phenylalanyl-tRNA synthetase. In addition to differences in chromatographic properties the three enzymes exhibit different affinities, in Tris-Cl buffer, toward purified species of valine and alanine tRNA's isolated from Escherichia coli. The two major chromatographic fractions have very similar sedimentation characteristics, which makes a monomer-dimer relationship unlikely.

Carbon Isotopes↗
PubMed1968

Alcohol dehydrogenase of Drosophila: interconversion of isoenzymes.

Isoenzymes of alcohol dehydrogenase extracted from Drosophila melanogaster are interconvertible and can be distinguished by electrophoretic mobility. When adsorbed on diethylaminoethyl cellulose, the faster-moving forms are converted to the slowest-moving form; the latter is converted to the former in the presence of 0.05 molar nicotinamide-adenine dinucleotide, and the conversion is accompanied by the binding of 3.5 moles of the dinucleotide per mole of enzyme. A change in heat stability accompanies the conversion of the slowest form of alcohol dehydrogenase to the fastest form; the latter becomes stable at 45 degrees C. The increased heat stability may indicate that a conformational change in the alcohol dehydrogenase occurs along with the binding of nicotinamide-adenine dinucleotide.

Alcohol Oxidoreductases↗
PubMedDate not supplied

Quantitative aspects of metal ion content and toxicity in Drosophila.

As a basis for both a genetic and a biochemical approach to a study of metal ion effects, a method for quantitating the toxic response of Drosophila to metal ions was developed. The response to 13 metal ions has been examined, including several chemical groups from the periodic table: the IIb ions Zn2+, Cd2+, and Hg2+; the IIa ions, Be2+, Mg2+, Sr2+, and Ba2+; the transition elements, Ni2+, Cu2+, Co2+, and Mn2+: and trivalent ions, Y3+ and Cr3+. The standard test procedure provides estimates of the median lethal concentration (LC50) and the range of the tolerance distribution both of which are obtained by the method of probit transformation. Range is defined as the change in concentration between the LC2.5 and the LC97.5. Estimation of range as the measure of the limits of the tolerance distribution was utilized to measure variation in the response to metals with time. Genetic characterization of strains will require strains of flies without overlapping tolerance ranges. Although there was a general trend of increasing values of range with increasing LC50 values, the exceptions (e.g., Cr3+ and Be2+) indicated that several factors may be involved in determining the range of lethal responses. Elemental analyses have been performed on flies before and after metal ion treatments to establish the amount of metal ion taken up and baselines for comparison. This study provides additional evidence that Drosophila is an appropriate organism for the study of specific biochemical alterations induced by metals, e.g., the cadmium-induced increase in Q(+)tRNAs.

Animals↗
PubMedDate not supplied

Synthesis of 3-(triethylstannyl)propanoic acid: an organotin mass label for DNA.

The synthesis of 3-(triethylstannyl)propanoic acid (TESPA), an organometallic reporter group that enables the mass labeling of oligonucleotides with stable isotopes of tin, is described. Synthesized from commercially available isotopically-enriched SnO2 in a five step process, the NHS ester of TESPA is produced with an overall yield of 40%. This simplification of the standard synthetic scheme, with two less synthetic steps and a coincident 60% yield increase, is accomplished through the use of the reagent N-(acryloxy)succinimide and the free radical initiator AMPN. The conditions for the attachment of the reporter group to priming oligonucleotides and the subsequent HPLC isolation of the labeled primers are also detailed.

Alloys↗