Lopez R A, Arce C A, Barra H S
Centro de Investigaciones en Química Biológica de Córdoba, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, Argentina.
Biochim Biophys Acta. 1990 Jun 19;1039(2):209-17. doi: 10.1016/0167-4838(90)90188-l.
Microtubule protein preparations purified from rat brain were used to study the effect of polycations and polyanions on the release of the COOH-terminal tyrosine of the alpha-chain of tubulin catalyzed by tubulin carboxypeptidase. (1) Most of the polycations and polyanions tested, independently of the ionogenic group, inhibited the reaction in a concentration-dependent fashion. Under steady-state conditions, detyrosination of the microtubule pool was inhibited to the same degree as occurred with the non-assembled tubulin pool, except in the case of chondroitin sulphate. This compound inhibited detyrosination of the non-assembled tubulin pool, but not that of microtubules. (2) Heparin, the most potent inhibitor tested, produced the dissociation of the carboxypeptidase from microtubules. Many, but not all, of the other microtubule-associated polypeptides were also dissociated by heparin. (3) Polylysine counteracted the inhibitory and dissociating effects of heparin. (4) Heparin protected tubulin carboxypeptidase against inactivation. Our results and previous reports describing, in nervous tissue, the presence of proteoglycans, RNA and basic proteins that inhibit detyrosination, suggest that tubulin carboxypeptidase might be physiologically modulated by electrically charged macromolecules.
从大鼠脑中纯化得到的微管蛋白制剂用于研究聚阳离子和聚阴离子对微管蛋白羧肽酶催化的微管蛋白α链羧基末端酪氨酸释放的影响。（1）所测试的大多数聚阳离子和聚阴离子，与离子基团无关，均以浓度依赖的方式抑制该反应。在稳态条件下，微管池的去酪氨酸化受到的抑制程度与未组装的微管蛋白池相同，但硫酸软骨素的情况除外。该化合物抑制未组装的微管蛋白池的去酪氨酸化，但不抑制微管的去酪氨酸化。（2）所测试的最有效的抑制剂肝素导致羧肽酶从微管上解离。许多但并非所有其他与微管相关的多肽也被肝素解离。（3）聚赖氨酸抵消了肝素的抑制和解离作用。（4）肝素保护微管蛋白羧肽酶不被灭活。我们的结果以及之前描述神经组织中存在抑制去酪氨酸化的蛋白聚糖、RNA和碱性蛋白的报道表明，微管蛋白羧肽酶可能在生理上受到带电大分子的调节。
