Yan Qiaojuan, Jiang Zhengqiang, Yang Shaoqing, Deng Wei, Han Lujia
Bioresource Utilization Laboratory, Engineering College, China Agricultural University, Beijing 100083, China.
Arch Biochem Biophys. 2005 Oct 1;442(1):72-81. doi: 10.1016/j.abb.2005.07.019.
A novel lectin (AMML) was isolated from a Chinese herb, i.e., the roots of Astragalus mongholicus, using a combination of ammonium sulfate fraction and ion exchange chromatographies. The molecular mass of intact AMML was determined to be 66,396 Da by MALDI-TOF mass spectrometry and 61.8 kDa by gel filtration, respectively. AMML was a dimeric protein composed of two identical subunits each with a molecular mass of 29.6 kDa. The lectin was a glycoprotein with a neutral carbohydrate content of 19.6%. The purified lectin hemagglutinated both rabbit and human erythrocytes, and showed preference for blood types O (native) and AB (trypsin-treated). Among various carbohydrates tested, the lectin was best inhibited by D-galactose and its derivatives with pronounced preference for lactose (3.13 mM). N-terminal amino acid sequence of AMML was determined as ESGINLQGDATLANN. The optimal pH range for lectin activity was between pH 4.5 and 7.5, and the lectin was active up to 65 degrees C. It also exerted antifungal activity against Botrytis cincerea, Fusarium oxysporum, Colletorichum sp., and Drechslera turcia but not against Rhizoctonia solani and Mycosphaerella arachidicola.
采用硫酸铵分级分离和离子交换色谱相结合的方法，从一种中国草药——蒙古黄芪的根中分离出一种新型凝集素（AMML）。通过基质辅助激光解吸电离飞行时间质谱法测定完整AMML的分子量为66,396 Da，通过凝胶过滤法测定其分子量为61.8 kDa。AMML是一种二聚体蛋白，由两个相同的亚基组成，每个亚基的分子量为29.6 kDa。该凝集素是一种糖蛋白，中性碳水化合物含量为19.6%。纯化后的凝集素能使兔和人的红细胞发生凝集，并且对O型（天然）和AB型（经胰蛋白酶处理）血型表现出偏好。在测试的各种碳水化合物中，该凝集素受D-半乳糖及其衍生物的抑制作用最强，对乳糖（3.13 mM）表现出明显的偏好。AMML的N端氨基酸序列测定为ESGINLQGDATLANN。凝集素活性的最佳pH范围在4.5至7.5之间，该凝集素在65摄氏度时仍具有活性。它还对灰葡萄孢、尖孢镰刀菌、炭疽菌属和小麦根腐病菌具有抗真菌活性，但对茄丝核菌和落花生球腔菌没有活性。
