High performance liquid chromatography of nucleic acids and the related compounds on a fluorinated silica gel column.

Separations of nucleic acids and the related compounds were investigated by HPLC on a new fluorinated bonded silica gel column. Polyadenylate (Poly (A)) enzymatic partial hydrolysate sample and the mixture of various polynucleotide samples were sufficiently separated by the reversed-phase mode using a gradient elution with aqueous ammonium acetate/acetonitrile system. Mixed-mode separation on the fluorinated bonded phase coated with a tert-alkylammonium salt was also examined for the separation of the various polynucleotides including tRNAs.     

Specific binding of lectins with the nucleus of the sea urchin embryo and changes in the lectin affinity of the embryonic chromatin during the course of development

(1) Embryonic cells of sea urchins were made permeable by treating them with glycerol solution for the purpose of allowing penetration of macromolecules into the cell. With the use of such permeabilized cells, several kinds of fluorescent dye-labeled lectins were introduced into the cell, and it was found that some lectins showed notable affinity with the nucleus as compared with cytoplasmic structures. (2) Isolated chromatin was incubated with several kinds of fluorescent dye-labeled lectins in vitro, and the amount of lectins bound with the chromatin was measured by fluorometry. By means of this method, the lectin-binding capacity of chromatin was estimated and compared at various stages of development. It was found that lectins could be classified into three groups according to the mode of binding with the chromatin: (a) Extent of binding increased notably at the gastrula stage (Con A and RCA-120); (b) extent of binding showed a temporary decrease at the gastrula stage (TTA); and (c) very low level of binding was maintained throughout all stages, and no particular change was observed at any stage of development (WGA, SBA, and UEA-I). (3) These facts seem to suggest that lectin-binding components are contained in sea urchin chromatin, and that drastic changes occur in these components of chromatin at the stage of gastrulation. It was proposed that the lectin-binding components such as proteoglycans and glycoproteins may play regulatory roles in embryonic chromatin at early stages of development.     

Oxidative degradation of thymine with O2 promoted by L-ascorbic acid and Cu(II) ion

Oxidation of thymine with O2 was promoted by copper(I) ion generated from reaction of L-ascorbic acid (AA) with copper (II) ion. The main oxidation products were thymine glycol (TG) and N-formyl-N'-pyruvylurea (FPU). At higher concentration of O2, formation of FPU was favored, while TG was dominant at higher Cu(II) ion and lower O2 concentrations. Reaction mechanism involving hydroxy thyminyl radical was proposed.     

GPI1 stabilizes an enzyme essential in the first step of glycosylphosphatidylinositol biosynthesis.

Attachment of glycosylphosphatidylinositol (GPI) is essential for the surface expression of many proteins. Biosynthesis of glycosylphosphatidylinositol is initiated by the transfer of N-acetylglucosamine from UDP-N-acetylglucosamine to phosphatidylinositol. In mammalian cells, this reaction is mediated by a complex of PIG-A, PIG-H, PIG-C, and GPI1. This complexity may be relevant for regulation and for usage of a particular phosphatidylinositol. However, the functions of the respective components have been unclear. Here we cloned the mouse GPI1 gene and disrupted it in F9 embryonal carcinoma cells. Disruption of the GPI1 gene caused a severe but not complete defect in the generation of glycosylphosphatidylinositol-anchored proteins, indicating some residual biosynthetic activity. A complex of PIG-A, PIG-H, and PIG-C decreased to a nearly undetectable level, whereas a complex of PIG-A and PIG-H was easily detected. A lack of GPI1 also caused partial decreases of PIG-C and PIG-H. Therefore, GPI1 stabilizes the enzyme by tying up PIG-C with a complex of PIG-A and PIG-H.     

Antioxidant Activity of 3-Methylthiopropylamine Hydrochloride

Antioxidant activities of various amino acids and some of their related substances on the autoxidation of sodium lenolenate in aqueous system were examined by TBA method. As the results, 3-methylthiopropylamine hydrochloride (MTPA) was found to be most effective in antioxidant activity among the substances tested. Also, it was an unique characteristic of MTPA that it was quite soluble in organic solvents, fats and oils as well as in water. At a temperature of less than 100°C, MTPA was quite stable in aqueous solution over whole pH range. Acute toxicity test of MTPA by oral administration of mice has indicated that LD₅₀ of MTPA was 4.5 g per kg.