Mizuno K, Kojima M, Matsuo H
Biochem Biophys Res Commun. 1985 Apr 30;128(2):884-91. doi: 10.1016/0006-291x(85)90129-9.
Paired basic residues, particularly Lys-Arg, are known as a typical site for proteolytic processing of prohormones. In this study, we confirmed the presence of a novel protease exhibiting substrate specificity toward Lys-Arg sequence. It was partially purified from the soluble fraction of bovine adrenomedullary chromaffin granules by using an affinity chromatography on soybean trypsin inhibitor-Sepharose. The enzyme, with optimal pH around 7.5-9.5, is classified into a serine-protease family by its inhibition spectrum. The enzyme specifically cleaves in between the Lys-Arg bonds of the peptides related to proenkephalins, but the sequences of Arg-Arg, Arg-Lys and a single basic residue (Arg or Lys) in the substrates are not affected by the enzyme. The unique substrate specificity of the enzyme suggests that it is distinct from pancreatic trypsin and may be physiologically involved in proenkephalin processing.
成对的碱性残基，尤其是赖氨酸-精氨酸，是激素原蛋白水解加工的典型位点。在本研究中，我们证实了一种新型蛋白酶的存在，该蛋白酶对赖氨酸-精氨酸序列具有底物特异性。通过使用大豆胰蛋白酶抑制剂-琼脂糖亲和色谱法，从牛肾上腺髓质嗜铬颗粒的可溶性部分中对其进行了部分纯化。该酶的最适pH约为7.5 - 9.5，根据其抑制谱被归类为丝氨酸蛋白酶家族。该酶特异性地切割与脑啡肽原相关的肽的赖氨酸-精氨酸键之间，但底物中精氨酸-精氨酸、精氨酸-赖氨酸和单个碱性残基（精氨酸或赖氨酸）的序列不受该酶影响。该酶独特的底物特异性表明它与胰蛋白酶不同，可能在生理上参与脑啡肽原的加工。
