Senescence-Related Endopeptidase Isozymes in Spirodela polyrrhiza Half-fronds Detected by Gel Electrophoresis

[Objective]To study endopeptidases in Spirodela polyrrhiza half-fronds during senescence and their characters. [Method]Changes in endopeptidase isoenzymes of the Spirodela polyrrhiza half-fronds during senescence were detected by gelatin-SDS-PAGE electrophoresis,and their types were analyzed with protease inhibitors. [Result]Six endopeptidases were detected in the Spirodela polyrrhiza half-fronds during senescence. Among them,HEP1,HEP2,HEP4 and HEP6 （high molecular-weight endoprotease） were senescence-related endopeptidases. [Conclusion]The metalloendopeptidase plays significant roles at the early stage of senescence,and the cysteine endopeptidase are the most abundant at the late stage of senescence.

二苯脲延缓紫萍半叶状体衰老的作用

在长日照条件下,10-7mol/L的二苯脲对紫萍半叶状体就有保绿的作用,10-5～2×10-4mol/L的二苯脲还可以明显地促进叶绿素的合成和干重的增加,提高丝氨酸乙醛酸转氨酶的活性,延缓半叶状体的衰老.实验结果表明,二苯脲本身具有细胞分裂素的活性,能代替内源细胞分裂素起到抗衰老的作用;二苯脲同时也能推迟半叶状体中内源细胞分裂素含量的降低.另外,在培养液中加入外源L-丝氨酸,可以抗拮二苯脲对紫萍半叶状体衰老的延缓作用,说明二苯脲抗衰老的机制类似于其它细胞分裂素.

凝胶电泳法研究紫萍半叶状体衰老期间的内肽酶同工酶

[目的]研究与紫萍半叶状体衰老相关的内肽酶及其性质。[方法]采用明胶-SDS-聚丙烯酰胺凝胶电泳技术分析与衰老相关的内肽酶同工酶,并用蛋白酶抑制剂分析内肽酶类型。[结果]对紫萍衰老期间内肽酶的分析表明,共有6种内肽酶出现,金属型蛋白酶HEP1和半胱氨酸型内肽酶HEP2、HEP4、HEP6是与衰老相关的内肽酶。[结论]在紫萍半叶状体衰老早期金属型内肽酶活性较强,而在衰老后期半胱氨酸型内肽酶大量出现并具有较高的活性。