Waite J H, Rice-Ficht A C
Marine Biology/Biochemistry Program, College of Marine Studies, University of Delaware, Lewes 19958.
Biochemistry. 1989 Jul 11;28(14):6104-10. doi: 10.1021/bi00440a056.
The vitellaria are an extensive network of glandular cells and ducts distributed throughout the peripheral tissues of the liver fluke Fasciola hepatica. Eggshell precursor proteins are produced and stockpiled in the vitelline cells of mature flukes. Vitelline protein C has an extraordinary composition: the amino acid 3,4-dihydroxyphenyl-L-alanine (DOPA) and histidine each comprise about 20% of the residues, while glycine represents 41-42% in all variants of what appears to be a microheterogeneous protein family. Protein C has an apparent molecular weight of 16,000-17,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Although the protein appears homogeneous following polyacrylamide gel electrophoresis in Tris-glycine with SDS and a acetic acid-urea, electrophoresis in borate, however, suggests that the vitelline protein consists of four or more closely related proteins weighing from 16,000 to 18,500. Isoelectric focusing of the protein family in the presence of 8 M urea resolved only two species having pI values of 6.89 and 6.99. A single N-terminus having the sequence H-H-W-D-G-DOPA-G-DOPA-G was detected. The primary structure of vitelline protein C is characterized by a repeated motif consisting of (G-X)n, where X is Ser, DOPA, or His. Most of the His occurs as G-H repeats in a pepsin-resistant fragment of the protein. Previously, a 31-kDa protein, representing up to 6% of the total protein in the fluke, was reported [Waite, J. H., & Rice-Ficht, A (1987) Biochemistry 26, 7819-7825] to contain significant levels of DOPA.(ABSTRACT TRUNCATED AT 250 WORDS)
卵黄腺是广泛分布于肝片吸虫（Fasciola hepatica）外周组织中的腺细胞和导管网络。卵壳前体蛋白在成熟吸虫的卵黄细胞中产生并储存。卵黄蛋白C具有特殊的组成：氨基酸3,4-二羟基苯-L-丙氨酸（DOPA）和组氨酸各自约占残基的20%，而甘氨酸在这个似乎是微不均一蛋白家族的所有变体中占41-42%。通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳，蛋白C的表观分子量为16,000-17,000。尽管在含有SDS的Tris-甘氨酸和乙酸-尿素的聚丙烯酰胺凝胶电泳后该蛋白看起来均一，但在硼酸盐中的电泳表明，卵黄蛋白由四种或更多种密切相关的蛋白组成，分子量在16,000至18,500之间。在8M尿素存在下对该蛋白家族进行等电聚焦仅分辨出两种等电点值分别为6.89和6.99的物种。检测到一个具有H-H-W-D-G-DOPA-G-DOPA-G序列的单一N末端。卵黄蛋白C的一级结构的特征是由(G-X)n组成的重复基序，其中X是丝氨酸、DOPA或组氨酸。大多数组氨酸以G-H重复的形式出现在该蛋白的胃蛋白酶抗性片段中。此前，据报道一种占吸虫总蛋白高达6%的31-kDa蛋白[Waite, J. H., & Rice-Ficht, A (1987) Biochemistry 26, 7819-7825]含有大量的DOPA。（摘要截短于250字）
