Jung-Yaw Lin

Isolation of four isotoxic proteins and one agglutinin from jequiriti bean (Abrus precatorius)

Abstract Four isotoxic proteins and one agglutinin were purified from the seeds of Abrus precatorius by Sepharose 4B and DEAE-cellulose column chromatography. Abrin-b and abrin-c which bind weakly on the Sepharose 4B are eluted from the column in the absence of galactose while abrin-a, abrin-d and abrus agglutinin which bind strongly are eluted with 0·1M galactose. The mol. wts of abrin-a and abrin-c are 63,000 and abrin-b, abrin-d and abrus agglutinin 67,000. The lethality of the four abrins was similar; 10, 25, 16 and 31 μg/kg body wt for abrin-a, b, c and d, respectively. The amino acid compositions of four isotoxic proteins and the A and B subunit of three isotoxic proteins are similar but not identical, and they are different from those of abrus agglutinin.

Studies on the antitumor lectins isolated from the seeds of Ricinus communis (castor bean).

Three toxic proteins and one agglutinin were purified from the seeds of Ricinus communis by a simple and fast method using Sepharose 4-B affinity chromatography followed by Sephadex G-100 gel filtration. The weakly adsorbed ricins A and B were retarded and eluted with the buffer from the affinity chromatographic column, while ricin C and ricinus agglutinin had to be eluted with 0.1 M galactose. The molecular weights of ricins A, B, and C were about 62,000 and that of ricinus agglutinin was 120,000, estimated by amino acid compositions and SDS gel electrophoresis. They all possessed two non-identical subunits: A and B chains linked by one disulfide bond. Their LD50 values were 4, 28, 14 and 112 micrograms per kg body weight of mice for ricins A, B and C and ricinus agglutinin, respectively. The amino acid compositions of the three toxins and their A and B subunits were very similar, but not identical, while ricinus agglutinin showed a different composition. Ricin A is a newly isolated lectin which has a strong inhibitory effect on the growth of tumor cells. By using cell cultures, it was demonstrated that the tumor cells were more sensitive to lectin than non-transformed cells, and that this could be caused by the higher binding affinity of lectin to tumor cells than to non-transformed cells.

Isolation of toxic and non-toxic lectins from the bitter pear melon Momordica charantia Linn

Abstract Toxic and non-toxic lectins, momordin and momordica agglutinin were isolated from Momordica charantia Linn. The mol. wt of momordin and momordica agglutinin were determined to be 23,678 and 31,762 respectively by SDS acrylamide gel electrophoresis and as gel filtration coupled with amino acid analyses. Both lectins are single polypeptide chains. The ld 50 of momordin was 5 mg per kg body weight and it inhibited protein biosynthesis of Ehrlich ascites tumor cells. Momordica agglutinin is able to agglutinate the human O type red blood cells at a concentration of 0·5 μg/ml. Galactose or its derivatives are able to inhibit the hemagglutination.

Toxicity of the cardiotoxic protein, flammutoxin, isolated from the edible mushroom Flammunlina velutipes

Abstract Flammutoxin is a cardiotoxic protein which has been purified from the edible mushroom, Flammulina velutipes . The protein has strong hemolytic activity against human group O red blood cells and calcium ions at physiological concentration can partially reverse the hemolytic effect. The inhibitory effect of the toxic protein on the respiration of Ehrlich ascites tumor cells was also suppressed by calcium ions. When the toxic protein was injected i.p. into mice, it caused the writhing reaction which was partially inhibited by antihistaminics. When the toxic protein was locally injected into rat paws, it induced severe edema.

Studies on the active principle from Abrus precatorius L. Leguminosae seed kernels

Abstract Abrin, a highly toxic protein, has been purified and crystallized with a yield of 0.15 per cent from the kernels of Abrus precatorius seeds. The purification involves extraction with 5 per cent acetic acid, ammonium sulfate fractionation and DEAE Sephadex column chromatography. The crystalline abrin is homogeneous with respect to sedimentation criterion. No hemagglutinating activity was detected in crystalline abrin. Based upon sedimentation equilibrium analysis, a molecular weight of 65 × 10 3 was calculated for the protein while amino acid and tryptic peptide map analysis indicates that the crystalline protein contains two peptide chains.

Distribution of I131-labeled abrin in vivo☆

Abstract Abrin, the crystalline toxic protein isolated from Abrus precatorius was greatly inactivated by iodination. Two hours after i.p. injection of I 131 -labeled abrin, about 12 per cent of injected protein was found in liver while much less was detected in other organs. The I 131 -abrin found in liver and spleen was intact as demonstrated by gel filtration.

Carbohydrate in abrin

Abstract Crystalline abrin contained 4·9 per cent of neutral sugar in addition to 9·3 residues of glucosamine per mole of abrin (molecular weight 65,000). The neutral sugars consist of mannose, xylose and fucose in ratios of 2·08:1·00:0·94. When abrin was treated with periodate, the residual toxicity was only a few per cent of that of native abrin. The periodate-treated abrin lost its anti-tumor activity as well as its inhibitory effect on the protein biosynthesis of Ehrlich ascites tumor cells.