摘要
C1027是含烯二炔发色团的大分子肽类新抗肿瘤抗生素,由一个蛋白和一个烯二炔发色团两部分构成。后者是活性部分,对肿瘤细胞有强杀伤作用,蛋白对发色团的活性有保护作用。蛋白和发色团在一定条件下可以重新组建成完整的C1027。C1027分子内的二硫键有辅助蛋白保护发色团的作用,当二硫键被还原后,C1027活性丢失加快。C1027被链霉蛋白酶降解产生一个分子量为3~5kDa的中间产物,此产物对肿瘤细胞的杀伤作用与完整C1027相同,表明C1027是可以裁剪的,保护发色团的最小肽段为3~5kDa。
The molecule
of C1027,an antitumor antibiotic with extremely potentcytotoxicity
against cultured cancer cells ,is composed of an enediyne chromophore
and an apoprotein of 10.5 kDa.These two parts of the
molecule,connecting each other through non-covalent binding,can be
dissociated and reconstituted.As determined by clonogenic assay,the
chromophore served asthe active part of the molecule,displaying
potent cytotoxicity similar to that of intact C1027.Theactivity of
free chromophore decreased more rapidly than that of intact
C1027,indicating thatapoprotein played a role in protecting the
chromophore from inactivation.By incubating together inphosphate
buffer ,the chromophore and apoprotein were reconstituted to form an
intact C1027.Theratio of chromophore and apoprotein remained 1 :1 in
the reconstituted molecule ,even though extraamount of chromophore
was added.The optimal condition for the reconstitution was pH 7.0 ,at
20℃for 12 h.When the disulfide bond of the apoprotein was reduced by
DTT ,the activity of C1027decreased more rapidly.C1027 was digested
by pronase and the produced fragments of variousmolecular weights
were examined by capillary electrophoresis.The cytotoxicity of 3~
5kDa fragmentapproximated that of intact C1027 and its IC50 value was
0.07 fmol·L-1.The results indicate thatthe intactness of the
apoprotein is not indispensable for stabilizing the chromophore and a
smallermolecule of 3~5kDa consisting of a peptide fragment and a
chromophore may retain full C1027activity.
出处
《药学学报》
CAS
CSCD
北大核心
1995年第5期336-342,共7页
Acta Pharmaceutica Sinica
基金
国家863计划资助