Donald J. Armstrong

Isolation of cytokinins from tRNA

Abstract A method is described for the isolation of cytokinins from tRNA. The cytokinin active ribosides are recovered from enzymatic hydrolysates of tRNA by extraction with ethyl acetate. The extracts are fractionated by chromatography on Sephadex LH-20 columns in 35% ethanol. The method appears to be quantitative and resolves individual cytokinins such as the ribosides 6-(3-methyl-2-butenylamino)-9-β d -ribofuranosylpurine (2iPA) and 6-(3-methyl-2-butenylamino)-2-methylthio-9-β- d -ribofuranosylpurine (ms2iPA).

Cytokinin from Soluble RNA of Escherichia coli: 6-(3-Methyl-2-butenylamino)-2-methylthio-9-β-D-ribofuranosylpurine

We have isolated a compound responsible for the cytokinin activity of soluble RNA from Escherichia coli. The structure, indicated as 6-(3-methyl-2-butenylamino)-2-methylthio-9-β-D-ribofuranosylpurine, C16H23N504S, on the basis of low-and high-reso!ution mass spectrometry, was established by unequivocal synthesis. The mass spectra, chromatographic behavior, and ultraviolet spectra of the compounds from natural and synthetic sources were identical.

Cytokinin Activity: Localization in Transfer RNA Preparations

Transfer RNA from yeast, liver, and Escherichia coli has cytokinin activity in the tobacco callus bioassay, whereas ribosomal RNA from yeast is inactive. In contrast to fractions of yeast transfer RNA rich in serine acceptor and cytokinin activity, preparations (70 to 90 percent pure) of arginine transfer RNA2, glycine transfer RNA, phenylalanine transfer RNA, and valine transfer RNA1 and of highly purified alanine transfer RNA from yeast were inactive at concentrations of 20 to 2500 micrograms per liter. One molecule of 6-(γ,γ-dimethylallylamino) purine per 20 molecules of yeast tRNA would account for the observed cytokinin activity. The number of major molecular species contributing to cytokinin activity of transfer RNA, therefore, must be small.

Cytokinin of wheat germ transfer RNA: 6-(4-Hydroxy-3-methyl-2-butenylamino) -2-methylthio-9-β-D-ribofuranosylpurine

A new modified nucleoside is responsible, in part, for the cytokinin activity of transfer RNA from wheat germ. The structure as judged by mass spec-trometry is 6-(4-hydroxy-3-methyl-2-butenylamino)-2-methylthio-9-β-D-ribofuran-osylpurine. Unequivocal synthesis afforded material having ultraviolet, mass spectral, and chromatographic properties identical with those of the natural product.

Leukocyte Peroxidase Deficiency in a Family with a Dominant Form of Kuf's Disease

Use of a spectrophotomtetric assay of peroxidase with p-phenylenediamine as cosubstrate demonstrated deficient enzymne activity in leukocytes from two patients with a dominantly inherited form of ceroid lipofuscinosis (Kufs disease) and a clinically hlealthy unaffected sibling. When the reaction was performned in the absence of added hydrogen peroxide, oxidation of the p-phenylenediamnine cosubstrate (indicating the presence of endogenous peroxide) occurred only with enzyme samnples from the three siblings but not with those from a large number of unrelated, unaffected controls. This demonstrates that the deficiency of peroxide) found previously in the recessively inherited infantile and juvenile formns of ceroid lipofuscinosis (Batten-Spielmeyer-Vogt disease) is also present in an adult form with dominant inheritance.

Cytokinins: Isolation and identification of 6-(3-methyl-2-butenylamino)-9-β-D-ribofuranosylpurine (2iPA) from yeast cysteine tRNA

Abstract A cytokinin in yeast cysteine tRNA has been isolated as the riboside and has been shown to have uv and mass spectra identical with those of synthetic 6-(3- methyl-2-butenylamino)-9-β - D -ribofuranosylpurine.