HbF-新晋[~Gy~I119(GH2)Gly→Arg]一种新的不稳定胎儿血红蛋白变异体

 1988年我室又发现一种新的慢泳异常胎儿血红蛋白(HbF)。先证者为一健康汉族女婴。醋纤膜电泳(pH8.6)示变异体区带位于HbF与Hb A_2之间,反相高效液相色谱(HPLC)示正常GγI峰前方出现一异常峰。异常Hb含量为Hb总量的16.8％。理化性质测定该变异体为一轻度不稳定Hb。结构分析证明该变异体为GγI链第119位(GH2)的甘氨酸(Gly)被精氨酸(Arg)取代。γ链GH2位于α_1γ_1接触面,此处的氨基酸置换可导致Hb的不稳定。此变异体被命名为HbF-新晋~(GγI)119(GH2)Gly→Arg]。

Hb F-Xin-Jin GγI 119 (GH2) Gly-Arg:A New Unstable Fetal Hemoglobin Variant

In addition to three new fetal hemoglobin (Hb) variants, which we have found before,another new slow-moving unstable fetal Hb variant was discovered during cord blood screening carried out in Urumqi.The propositus was a healthy female baby of Han nationality The electrophorelic mobility of the variant on cellulose acetate slips was between Hb F and Hb A2 at pH 8.6 Separation of the globin chains by reserve phase HPLC showed an additional peak which eluted faster than that of normal G*********rI chain.The variant comprised 16.8% of the total Hb.The heat-denatured Hb was 26%} Heinz body production rate was 72% (both higher than normal);and heat-denaturation curve of the variant showed it was faster than those of Hb A and Hb F.These data indicated that the variant was a slightly unstable one.According to amino acid composition and sequence analysis,the variant was identified that a substitution of Arg for Gly has taken place at position 119 on G********rI chain.This position is involved in *********a1 *********r1 contact which is one of the important factors of Hb stability.The variant was named Hb F-Xin-Jin, or G**********rI 119 (GH2) Gly************-Arg.