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Biomedical subjects

S L Li

Publications and source records attributed to S L Li.

At least 109 records · Page 6Linked to original sources
PubMed1980

Purification and physicochemical properties of ricins and agglutinins from Ricinus communis.

Two toxin ricins and two agglutinins have been purified from the seeds of Ricinus communis by an improved procedure based on ion-exchange chromatography and gel filtration. One of the two purified ricins binds to Sepharose 4B while the other does not. The physicochemical properties of the four Ricinus lectins are presented and the possible relationships of these Ricinus lectins to those previously described are discussed.

Amino Acids↗
PubMed1976

The structure of monellin and its relation to the sweetness of the protein.

The sweet protein monellin [1-3] has been shown to consist of two non-identical subunits of 50 and 42 amino acid residues, which were separated electrophoretically and chromatographically. Automatic sequential Edman degradation gave the complete sequence of the longer subunit, and a partial sequency of the shorter one. It was found that the sweetness of monellin requires the undissociated molecule. The individual subunits were not sweet, neither did they block the sweet sensation of sucrose or monellin. Blocking of the single SH of monellin abolished its sweetness as did reaction of the single methionyl residue with CNBr. Since the cysteinyl and methionyl residues appear to be adjacent, it is suggested that this part of the molecule is essential for its sweetness.

Amino Acid Sequence↗
PubMed1974

Amino-terminal sequence of the tryptophan synthetase alpha chain of Bacillus subtilis.

The sequence of the 46 NH(2)-terminal residues of the tryptophan synthetase alpha chain of Bacillus subtilis was determined and compared with the corresponding sequences of Escherichia coli, Shigella dysenteriae, Salmonella typhimurium, Aerobacter aerogenes, Serratia marcescens, and Pseudomonas putida. A deletion of six residues was found at the NH(2)-terminal end of the alpha chain of B. subtilis.

Amino Acid Sequence↗
PubMed1973

Nucleotide sequence divergence in the -chain-structural genes of tryptophan synthetase from Escherichia coli, Salmonella typhimurium, and Aerobacter aerogenes.

Two different estimates were obtained for the extent of nucleotide sequence divergence in the structural genes of the tryptophan synthetase alpha-chains of Escherichia coli, Salmonella typhimurium, and Aerobacter aerogenes. One estimate was based on comparisons of the amino acid sequences of the respective alpha chains. The other was derived from measurements of the thermal stability of RNA-DNA hybrids formed with phage DNA carrying the alpha-chain structural gene of E. coli and labeled messenger RNA from the three bacterial species. Comparison of the two estimates suggests that during the course of evolution synonymous codon changes have accumulated in the alpha-chain-structural genes.

Amino Acid Sequence↗