摘要
目的 研究缓症链球菌外毒素蛋白的分子量、等电点、氨基酸组成及N 末端序列。方法 将纯化的毒素蛋白用SDS PAGE电泳 ,据低分子量标准蛋白质算出其相对分子质量 ;以微型聚丙烯酰胺等电聚焦 (miniIEF)法进行此毒素蛋白的等点电测定 ;采用电印迹将SDS PAGE电泳胶上的毒素蛋白转移到PVDF膜上 ,用Beckman 34 4HPLC仪测定外毒素蛋白的氨基酸组成 ;用自动化蛋白质序列仪测定缓症链球菌外毒素N 末端氨基酸序列。结果 缓症链球菌外毒素蛋白的相对分子质量为 34 0 0 0 ;测定毒素蛋白的等点电为 6 .2 ,是一种偏酸性蛋白 ;外毒素蛋白由 1 7种氨基酸组成 ,其中谷氨酸、甘氨酸、丙氨酸、门冬氨酸、赖氨酸、缬氨酸等氨基酸含量较高 ;缓症链球菌外毒素蛋白N 末端氨基酸序列为 :VSNLSRGMGA ,本毒素N 末端氨基酸序列与β溶血链球菌外毒素蛋白 (SPEA、SPEB、SEPC)N 末端氨基酸序列不同。结论 此外毒素蛋白的分子量、等电点、氨基酸组成和末端氨基酸序列均与其他 β溶血性链球菌外毒素不同 。
Purpose To determine the molecular weight,isoelectric point (pI),amino acid compositions and N terminal amino acid sequence of streptococcus mitis pyrogenic exotoxin(SMPE). Methods The molecular weight and pI of SMPE were determined by 12% sodium dodecyl sulfate polyacrylamide gelelectrophoresis (SDS?PAGE) and by agarose thin layer isoelectric focusing (IEF) respectively.Amino acid composition was detected with Beckman 344 HPLC.The N terminal amino acid sequencing of SMPE was performed by automated Edman degradation in gas phase sequenator after the band of SMPE in SDS?PAGE was transferred to polyvinyl difluoride(PVDF) membrane by electrophoretic transfer. Results The presents of experiments demonstrated that the molecular weight,the pI of SMPE were 34 000 and 6.2 respectively.17 kinds of amino acid residues were shown in amino acid analysis.The result also showed that among all existing residues E,G,A,K,V were rather rich.The N terminal amino acid sequence of SMPE was V S N L S R G M G A.And the sequence indicated that there was no homology between SMPE and any other member of the pyrogenic toxin family including streptococcus pyrogenic exotoxin (SPE) A,B,and C. Conclusions The molecular weight,isoelectric point,amino acid composition and N terminal amino acid sequence of the SMPE are differ from that of any other kind of β haemolytic SPEs.SMPE is a novel SPE.
出处
《上海医科大学学报》
CSCD
2000年第4期235-237,共3页
Journal of Fudan University(Medical Science)
关键词
缓症链球菌
致热性外毒素
毒素蛋白
streptococcus mitis
pyrogenic exotoxin
molecular weight
isoelectric point
amino acid composition
N terminal amino acid sequence
