Garcia-Pardo A
Z Immunitatsforsch Immunobiol. 1978 Jun;154(3):218-25.
Molecular weight determinations of immunoglobulin D suggest the presence of an extra region of the delta chain. In an attempt to locate this region, an IgDlambda myeloma protein (Gur), was digested with trypsin for 4 min at 56 degrees and the Fc fragment isolated by ion exchange chromatography. N-terminal analysis of this fragment showed a heterogeneity in the site of splitting by trypsin. The Fc was digested with pepsin and trypsin and the cysteine containing peptides isolated by a two dimensional paper high voltage electrophoresis (diagonal map) at pH 3.5. Further purification of these peptides was carried out by HVE at pH 6.5 and 2.1 and their amino acid composition and partial sequence were determined. Only five cysteic acid peptides were obtained, one corresponding to the inter heavy-heavy bridge and the other four, to intra chain bridges. This finding would exclude the possibility of an extra "classical domain" in this region. The position of these peptides in the delta chain has been arranged based on homology with the other classes of immunoglobulins.
免疫球蛋白D的分子量测定表明δ链存在一个额外区域。为了定位该区域，将一种IgDλ骨髓瘤蛋白（Gur）在56℃用胰蛋白酶消化4分钟，然后通过离子交换色谱法分离Fc片段。对该片段的N端分析显示，胰蛋白酶切割位点存在异质性。用胃蛋白酶和胰蛋白酶消化Fc，并在pH 3.5条件下通过二维纸高压电泳（对角线图谱）分离含半胱氨酸的肽段。通过pH 6.5和2.1的高压电泳对这些肽段进行进一步纯化，并测定其氨基酸组成和部分序列。仅获得了五个半胱氨酸肽段，一个对应重链间桥，另外四个对应链内桥。这一发现排除了该区域存在额外“经典结构域”的可能性。这些肽段在δ链中的位置已根据与其他类免疫球蛋白的同源性进行了排列。
