Macedo Maria Lígia Rodrigues, Freire Maria das Graças Machado, Martins Ludmilla T D Mendes, Martinez Diego S T, Gomes Valdirene M, Smolka Marcos B, Toyama Marcos H, Marangoni Sérgio, Coelho Luana Cassandra B B
Laboratório de Purificação de Proteínas e suas Funções Biológicas, Departamento de Ciências Naturais, Universidade Federal de Mato Grosso do Sul, CP 210, CEP 79603-011, Três Lagoas, MS, Brazil.
J Agric Food Chem. 2004 Dec 15;52(25):7548-54. doi: 10.1021/jf048535p.
This study starts by isolating and characterizing the first protein from Labramia bojeri seeds, which belong to the Sapotaceae family. The purified lectin analyzed by SDS-PAGE with and without beta-mercaptoethanol shows two protein bands (M(r) = 19 and 20 kDa), which cannot be resolved. Protein bands have shown similar characteristics as molecular masses, determined by gel filtration and native gel; N-terminal sequences presented a difference in their isoelectric points. We have suggested that those protein bands might be variants of the protein named Labramin. The sequence database search has shown that the N-terminal sequence of Labramin presented a high degree of homology to Kunitz-type trypsin inhibitor (82-52%) despite no trypsin inhibition activity detection. The lectin-like form from Labramin was better inhibited by glycoproteins and has also presented growth inhibition of the fungus Colletotrichum lindemuthianum and the yeast Saccharomyces cerevisiae, but it has not presented an apparent effect on Fusarium oxysporum.
本研究首先从属于山榄科的博氏蛋黄果种子中分离并鉴定了第一种蛋白质。用SDS-PAGE分析纯化的凝集素，无论有无β-巯基乙醇，均显示出两条无法分辨的蛋白带（分子量分别为19 kDa和20 kDa）。通过凝胶过滤和天然凝胶测定，蛋白带显示出与分子量相似的特征；N端序列的等电点存在差异。我们认为这些蛋白带可能是名为Labramin的蛋白质的变体。序列数据库搜索表明，尽管未检测到胰蛋白酶抑制活性，但Labramin的N端序列与Kunitz型胰蛋白酶抑制剂具有高度同源性（82%-52%）。Labramin的凝集素样形式受糖蛋白的抑制作用更强，对真菌炭疽菌和酿酒酵母也有生长抑制作用，但对尖孢镰刀菌没有明显影响。
