Kawasaki N, Kawasaki T, Yamashina I
J Biochem. 1983 Sep;94(3):937-47. doi: 10.1093/oxfordjournals.jbchem.a134437.
A serum lectin specific for mannose and N-acetylglucosamine residues was isolated from human serum to near homogeneity mainly by affinity chromatography on a column of Sepharose 4B-mannan. The lectin, called mannan-binding protein, was a glycine-rich protein with an apparent molecular size of approximately 600,000 daltons, and had a subunit structure consisting of a single component with an apparent molecular weight of 31,000. Binding of the isolated lectin to 125I-labeled mannan was dependent upon the presence of Ca2+, proportional to the protein added, and a reversible and saturable process. Scatchard plot analysis of binding data indicated the presence of a binding site with a dissociation constant of 2.3 X 10(-9) M and a maximum capacity of 4.3 pmol of 125I-labeled mannan per microgram of protein (2.6 mol of mannan per mol of the protein). The mannan-binding protein, is different from C-reactive protein (CRP) and amyloid P-component (SAP), both of which are serum components known to bind polysaccharides in the presence of Ca2+. A distinct binding activity toward mannan which did not require Ca2+ was attributed to immunoglobulins (IgG).
一种对甘露糖和N-乙酰葡糖胺残基具有特异性的血清凝集素主要通过在琼脂糖凝胶4B-甘露聚糖柱上进行亲和层析从人血清中分离至接近均一状态。这种凝集素称为甘露聚糖结合蛋白，是一种富含甘氨酸的蛋白质，表观分子大小约为600,000道尔顿，具有由一个表观分子量为31,000的单一成分组成的亚基结构。分离的凝集素与125I标记的甘露聚糖的结合依赖于Ca2+的存在，与添加的蛋白质成比例，并且是一个可逆且可饱和的过程。结合数据的Scatchard图分析表明存在一个结合位点，其解离常数为2.3×10(-9)M，每微克蛋白质对125I标记的甘露聚糖的最大结合容量为4.3皮摩尔（每摩尔蛋白质2.6摩尔甘露聚糖）。甘露聚糖结合蛋白不同于C反应蛋白（CRP）和淀粉样P成分（SAP），这两者都是已知在Ca2+存在下能结合多糖的血清成分。对甘露聚糖的一种不依赖Ca2+的独特结合活性归因于免疫球蛋白（IgG）。
