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Biomedical subjects

Z Yu

Publications and source records attributed to Z Yu.

At least 379 records · Page 21Linked to original sources
PubMed1990

[Separation and purification of the toxic protein of Bacillus sphaericus Ts-1].

Bacillus sphaericus strain Ts-1 is highly insecticidal to larvae of the mosquito. It's insecticidal component is toxic proteins. The toxin was extracted from spore-crystal complexes by disruption in a Sonicator Cell Disruptor Model W-220F followed by treatment with 0.05 mol/L NaOH. Fraction recovered from chromatography of the spore-crystal complexes on column of Sephadex G-200 were assayed against mosquito larvae and the toxic fractions from gel chromatography were subjected to SDS-PAGE. The toxic proteins in B. sphaericus Ts-1 spore-crystal complex migrated in position corresponding to 42kD and 43kD. Bioassay of the two purified proteins prepared by PAGE indicated that they were all toxic to mosquito larvae. Toxic protein was further purified by DEAE-cellulose chromatography. The toxic protein with a molecular weight of 42kD was obtained.

Animals↗
PubMed1989

Novel inhibitors of enkephalin-degrading enzymes. II: N5'-substituted-4-thioxohydantoic acids as aminopeptidase inhibitors.

Some 2-substituted-(2'-aminophenyl)-4-thioxohydantoic acids (o-amino PTC-amino acids) have antinociceptive activity when administered (icv) alone (IC50 = 0.04-0.87 microM/animal) and show a striking prolongation of the antinociceptive action of (D-Ala-2 D-Leu5)-enkephalin (DADL) in combination. The effects are thought to be mediated via opioid receptors since they are naloxone-reversible. Although inhibitors of the enkephalin degrading puromycin-insensitive, bestatin-sensitive aminopeptidase (possibly aminopeptidase M) their action is weak (IC50 = 32 microM leucine, 536 microM, glycine) and they might be considered to have a direct antinociceptive effect on opioid receptors. The titled compounds constitute novel 'lead' compounds for the development of potent aminopeptidase M inhibitors.

Aminopeptidases↗
PubMed1989

[Studies on the quality of enzyme preparations (X)--urokinase preparation].

Urokinase preparations were investigated with a view to comparing their quality by enzymological methods. These studies were carried out on 10 kinds (9 kinds of preparations produced from human urine and one kind of preparation produced from tissue culture) of commercially available urokinase preparations. The potency of all preparations assayed by the two-stage method were found to be within the range of permissible content. Because there are two molecular weight types (molecular weight: 54,000 and 33,000) of urokinase. the distribution of two types of urokinase in preparations was determined. Human urine urokinase preparations contained mainly the high molecular weight type urokinase (over 90%), and the tissue culture preparation contained the low molecular weight type urokinase alone.

Chromatography, High Pressure Liquid↗
PubMed1989

Comparative inhibition of ras p21 protein synthesis with phosphorus-modified antisense oligonucleotides.

A rabbit reticulocyte lysate translation assay was used to quantitatively compare a series of antisense oligodeoxyribonucleotides (11-mers) having different internucleoside linkages and various degrees of complementarity (100-80%) with the start codon and downstream 8 bases of Balb-ras p21 mRNA. The oligomers had either contiguous phosphodiester, or alternating methylphosphonate-phosphodiester, or contiguous methylphosphonate, or contiguous phosphorothioate linkages. Under the conditions used for the assay, all of the test compounds when present in about 10(3)-10(4) excess over mRNA (15 nM mRNA) inhibited protein synthesis to a degree which was dependent on both the concentration and sequence of the oligomer. At low concentrations (12.5-25 microM), the phosphorothioate analogs were the most potent inhibitors of p21 protein synthesis; however, a sequence non-specific effect for these oligomers was dominant at higher concentrations of oligomer (100-200 microM). The methylphosphonate oligomers appeared to be slightly more discriminant. Relative hybridization strengths were assessed by melting (Tm) studies using a DNA oligomer target to mimic the mRNA.

Animals↗