Unlike the European leech Hirudo medicinalis, the Asian jawed leech Hirudinaria manillensis is specialized for feeding on mammalian blood. In the salivary glands of both these leeches, there is a potent inhibitor of thrombin, called hirudin, which acts as an anticoagulant. We have reported previously the isolation and purification of a variant of hirudin, called bufrudin, from the head portions of Hirudinaria. In the present study, the complete amino acid sequence of bufrudin was determined by automated Edman degradation of peptide fragments generated after cleavage of protein with trypsin or thermolysin. Comparison of the primary structure of bufrudin, with hirudin HV1, show about 70% sequence identity with deletion of two amino acids, but the key amino acids at the C-terminus, involved in the inhibition of thrombin, are conserved. However, similar sequence comparison of bufrudin with hirullin P18, a hirudin variant isolated from the same leech species but from whole leech, instead of heads, reveals even less sequence identity of about 60%. From the amino acid sequence, it is suggested that the conformation of the C-terminal portion of bufrudin may be significantly different from hirullin P18, but similar to hirudin HV1, upon its interaction with thrombin. These results indicate that, as with Hirudo leech, various isoforms of hirudin also exist in Hirudinaria leech, with a significant change occurring in the structure of the molecule during the evolution of leeches.

中文翻译：

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来自水Hi水Hi的水rud素变体的完整氨基酸序列。

与欧洲水echHirudo medicinalis不同，亚洲jaw水echHirudinaria manillensis专门用于哺乳。在这两个水ches的唾液腺中，有一种有效的凝血酶抑制剂，称为水rud素，可作为抗凝剂。我们以前曾报道过从水rud的头部分离和纯化水hi素的一种变体，称为水b素。在本研究中，通过用胰蛋白酶或嗜热菌蛋白酶切割蛋白质后产生的肽片段的自动Edman降解来确定布德富丁的完整氨基酸序列。布佛丁与水hi素HV1的一级结构的比较显示，约70％的序列同一性与两个氨基酸的缺失有关，但C末端的关键氨基酸被保留，参与了凝血酶的抑制作用。然而，bufrudin与hirullin P18的相似序列比较，hirudin P18是从相同的水ech物种中分离而从整个水ech而不是从头部分离的水rud素变体，显示出甚至更少的约60％的序列同一性。从氨基酸序列可以看出，bufrudin C-末端部分的构象可能与hirullin P18显着不同，但与水rud素HV1类似，因为它与凝血酶相互作用。这些结果表明，与Hirudo水ech一样，水rud水various也存在水in素的各种同工型，水进化过程中分子的结构发生了显着变化。从氨基酸序列可以看出，bufrudin C-末端部分的构象可能与hirullin P18显着不同，但与水rud素HV1类似，因为它与凝血酶相互作用。这些结果表明，与Hirudo水ech一样，水rud水various也存在水in素的各种同工型，水进化过程中分子的结构发生了显着变化。从氨基酸序列可以看出，bufrudin C-末端部分的构象可能与hirullin P18显着不同，但与水rud素HV1类似，因为它与凝血酶相互作用。这些结果表明，与Hirudo水ech一样，水rud水various也存在水in素的各种同工型，水进化过程中分子的结构发生了显着变化。