Büllesbach E E, Gowan L K, Schwabe C, Steinetz B G, O'Byrne E, Callard I P
Eur J Biochem. 1986 Dec 1;161(2):335-41. doi: 10.1111/j.1432-1033.1986.tb10452.x.
A relaxin-like molecule has been isolated from the ovaries of the spiny dogfish (Squalus acanthias) which consists, like porcine relaxin, of two chains linked by the insulin-type disulfide bonds. The total number of amino acids is 54 of which 24 are in the A chain and 30 in the B chain. The molecular masses, calculated from the amino acid compositions, are 2510 Da for the A chain and 3370 Da for the B chain, making a total of 5880 Da. The N-terminus of the B chain is protected by a 5-oxoproline (pyrrolidone carboxylic acid) residue which is also found in the same position in the relaxins of sand tiger shark, pig, and man, whereas the relaxin of the rat has its 5-oxoproline residue at the N-terminal of the A chain. By all available criteria, S. acanthias relaxin is a typical member of the relaxin family although the sequence homology to mammalian relaxins is limited to about 45% of its amino acid residues. In contrast, the dogfish relaxin shows about 80% homology with sand tiger shark relaxin (the first such interspecies similarity to be observed) and has about twice the biological activity (mouse pubic symphysis test) when compared to sand tiger relaxin.
从棘鲨（Squalus acanthias）卵巢中分离出一种类松弛素分子，它与猪松弛素一样，由通过胰岛素型二硫键相连的两条链组成。氨基酸总数为54个，其中A链有24个，B链有30个。根据氨基酸组成计算，A链的分子量为2510 Da，B链为3370 Da，总计5880 Da。B链的N端由一个5-氧代脯氨酸（吡咯烷酮羧酸）残基保护，在沙虎鲨、猪和人的松弛素中该残基也位于相同位置，而大鼠松弛素的5-氧代脯氨酸残基位于A链的N端。根据所有现有标准，棘鲨松弛素是松弛素家族的典型成员，尽管其与哺乳动物松弛素的序列同源性仅限于约45%的氨基酸残基。相比之下，棘鲨松弛素与沙虎鲨松弛素显示出约80%的同源性（这是首次观察到的种间相似性），并且与沙虎鲨松弛素相比，其生物活性约为两倍（小鼠耻骨联合试验）。
