Teixeira Raphael D, Ribeiro Henrique A L, Gomes Marco-Túlio R, Lopes Miriam T P, Salas Carlos E
Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, UFMG, 31270-901 Belo Horizonte, MG, Brasil.
Plant Physiol Biochem. 2008 Nov;46(11):956-61. doi: 10.1016/j.plaphy.2008.06.010. Epub 2008 Jun 21.
Prior evidence suggests that proteinases in latex from Caricaceae protect against injuries induced by physical wounding. While the proteolytic enzymes from Carica papaya are well characterized, the homologues from Carica candamarcensis were not given similar attention, probably because its distribution is restricted to South American regions. We describe the chromatographic steps to fractionate 14 components from C. candamarcensis, 12 of them displaying amidase activity. The mass of these proteins plus two others isolated by HPLC rank between 23,943 and 22,991Da, and their N-terminal sequences showed similarities or identities with the enzymes described earlier in this species. Following CM-Sephadex chromatography two major peaks containing proteolytic activity were resolved. Each of these peaks was further resolved by Mono S chromatography yielding several purified fractions. The kinetic parameters of two of the Mono S purified enzymes originated from each of the CMS-Sephadex peaks were determined. While the Km with (Pyr-Phe-Leu-pNA), is similar in both enzymes, the kcat for one of them is 10-fold lower than the other. Based on these differences it is proposed that two groups of proteinases exist in latex of C. candamarcensis.
先前的证据表明，番木瓜科植物乳胶中的蛋白酶可防止物理创伤引起的损伤。虽然番木瓜的蛋白水解酶已得到充分表征，但番木瓜（Carica candamarcensis）的同源物却未受到类似关注，可能是因为其分布仅限于南美地区。我们描述了从番木瓜中分离出14种成分的色谱步骤，其中12种具有酰胺酶活性。这些蛋白质以及另外两种通过高效液相色谱法分离出的蛋白质的质量在23,943至22,991道尔顿之间，它们的N端序列与该物种先前描述的酶具有相似性或一致性。经过CM - 葡聚糖凝胶色谱后，分离出了两个具有蛋白水解活性的主要峰。每个峰通过Mono S色谱进一步分离，得到几个纯化的组分。测定了源自每个CM - 葡聚糖凝胶峰的两种Mono S纯化酶的动力学参数。虽然两种酶对（Pyr - Phe - Leu - pNA）的Km相似，但其中一种酶的kcat比另一种低10倍。基于这些差异，有人提出番木瓜乳胶中存在两组蛋白酶。
