| A lectin named PCLII with multi-functions was isolated from the rhizomes of polygonatum cyrtonema Hua, a liliaceae plant used as traditional Chinese herbal medicine. PCLII can bind mannose and silia acid, it also can agglutinate rabbit erythrocytes and gastric tumor cell lines SGC and HSC strongly and inhibite the growth of some pathogens. PCLII is a strong mitogen toward human T-lymphocytes and an efficient Ca2* antagonist (CA) or Ca2+ channel blocker (CCB). An in vitro plantlet regeneration system was established from rhizome lumps in Polygonatum cyrtonema Hua and mannose-binding lectin in cultured rhizome was determined by SDS-PAGE and hemagglutination assays and also analysised by RT-PCR and comparison of the nueleotide sequences and amino acid deduced with natural Polygonatum cyrtonema Hua lectin II.. Calli were induced on Murashige-Skoog (MS) medium containing 0.5mg/l to 2.0 mg/12,4-dichlorophenoxyacetic acid (2,4-D) and 0.5 rag/1 to 1.0 mg/1 6-benzylaminopurine (6BA). A high frequency of callus induction was obtained on MS medium supplemented with 2. 0 mg/1 2, 4-D and 1. 0 mg/1 6BA. Shoot buds were formed on subcultured pieces of callus with MS medium containing 0.3 mg/1 naphtaleneacetic acid (NAA) and 2mg/16BA. The regenerated shoots rooted readily on MS medium plus 0.5 mg/1 NAA. The regenerated plantlets were acclimatized and successfully transferred to pots. SDS-PAGE analysis and hemagglutination assays showed the composition of proteins, especially the prominent mannose-binding lectin in cultured rhizomes were comparable to that in wild rhizomes of Polygonatum cyrtonema Hua. PCL II had two mutations in nueleotide sequences and amino acid sequence compared with that of natural PCL II.The effect of chemical modification of amino acid residues upon haemagglutination and mitogenic activity toward T-lymphocytes was investigated. Modification of tyrosine (1-acetylimidazole and 4-nitrobenzenesulphonyl fluoride) did not alter haemagglutination but decreased mitogenic activity by about one half. In contrast, modification of tyrosine with tetranitromethane resulted in almost complele loss of haemagglutination acitivty but did not affect mitogenesis. Modification of serine/threonine (p-methylbenzene sulphonic acid), arginine (diacetyl), methionine (iodoactic acid) had little or no effect on either activity. Modification of carboxyl groups of aspartate/glutamate with dimethylaminopropyl-ethy-carbodiimide HC1 eliminated haemagglutination completely but had little effect on migotenic activity. Modification of histidine with diethylpyrocarbonale resulted about a half decrease of haemagglutination, but the mitogenic activity was intact. To modify lysine with 2, 4, 6-trinitrobenzene sulphonic acid accompanied with the decrease of haemagglutination and raitogenic activity both.Modification of amino acids can indicate which are important indetermining the lectin' s activity. Results indicated that the phenolic hydroxly group of tyrosine contributed to mitogenic acitivty but was much less important for haemagglutination. In contrast, the phenyl ring was not important for mitogenesis but was essential for haemagglutination. The carboxyl group of aspartame and glutamate and the imidazole group of histidene were also important for haemagglntination but not for mitogenesis. The amino group of Lys was necessary for haemagglutination and mitogenic activity.Together the results show that chemical modification of the lectin can affect heamagglutination and mitogenic activity separately. This indicates that the polygonatum cyrtonema Hua. lectin II has at least two active centres which play different roles in determining its activity. The confromational changes of polygonatum cyrtonema Hua. lectin II modified by reagents were studied by fluorescence spectrum and The fluorescence quenching study on PCLII with CsCU KI and acrylamide showed they all quenched the fluorescence of lectin through dynamic quenching mechanism.The antiviral activity of Polygonatum cyrtonema Hua. lectin II was determined by inhibit...
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