Skladanowski A C, Newby A C
Department of Cardiology, University of Wales College of Medicine, Heath Park, Cardiff, U.K.
Biochem J. 1990 May 15;268(1):117-22. doi: 10.1042/bj2680117.
A soluble 5'-nucleotidase was purified 200-fold from pigeon heart. The enzyme (1) had an apparent molecular mass close to 150 kDa, (2) had a neutral pH optimum and hydrolysed a wide range of nucleoside 5'-monophosphates with a 15-fold preference for AMP over IMP, (3) at near-physiological concentrations of AMP was activated by ADP but not by ATP, (4) was inhibited by high Mg2+ concentration and high ionic strength, (5) was weakly inhibited by p-nitrophenol phosphate and Pi, and (6) was non-competitively inhibited more potently by 5'-deoxy-5'-isobutylthioinosine than by 5'-deoxy-5'-isobutylthioadenosine, but not by [alpha,beta-methylene]ADP. The data show that the enzyme is distinct from the ecto-5'-nucleotidase and from the previously purified IMP-specific 5'-nucleotidase. They also predict that the enzyme is activated during ATP catabolism and hence will generate a more-than-linear increase in the adenosine-formation rate in response to an increase in cytosolic AMP concentration.
从鸽心纯化出一种可溶性5'-核苷酸酶，纯化倍数达200倍。该酶：(1) 表观分子量接近150 kDa；(2) 最适pH呈中性，可水解多种核苷5'-单磷酸，对AMP的水解偏好性比对IMP高15倍；(3) 在接近生理浓度的AMP条件下，被ADP激活，但不被ATP激活；(4) 被高浓度Mg2+和高离子强度抑制；(5) 被对硝基酚磷酸酯和磷酸根离子微弱抑制；(6) 与5'-脱氧-5'-异丁硫基腺苷相比，5'-脱氧-5'-异丁硫基肌苷对其非竞争性抑制作用更强，但不受[α,β-亚甲基]ADP抑制。数据表明，该酶与胞外5'-核苷酸酶及先前纯化的IMP特异性5'-核苷酸酶不同。数据还预测，该酶在ATP分解代谢过程中被激活，因此，随着胞质AMP浓度升高，腺苷生成速率将呈超线性增加。
