Epstein P M, Andrenyak D M, Smith C J, Pappano A J
Biochem J. 1987 Apr 15;243(2):525-31. doi: 10.1042/bj2430525.
The activities of cyclic AMP phosphodiesterase (3',5'-cyclic nucleotide 5'-nucleotidohydrolase, EC 3.1.4.17) and adenylate cyclase [ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1] and calmodulin content during development of chick ventricular myocardium were determined. The specific activity of cyclic AMP phosphodiesterase was relatively low in early embryos, increased during embryogenesis by about 4-fold to reach highest values just before hatching, and then decreased by approx. 30% within 1 week after hatching. In contrast, adenylate cyclase did not change during embryonic development, but increased by approx. 50% within 1 week after hatching. Calmodulin content remained constant at 9 micrograms/g wet wt. during embryonic development and decreased to 6 micrograms/g wet wt. by 1 week after hatching. DEAE-Sephacel chromatography of chick ventricular supernatant revealed a single major form of cyclic nucleotide phosphodiesterase activity in early embryonic (9-day E) and hatched (6-day H) chicks. This enzyme form was eluted at approx. 0.27 M-sodium acetate, hydrolysed both cyclic AMP and cyclic GMP, and was sensitive to stimulation by Ca2+-calmodulin, with an apparent Km for calmodulin of approx. 1 nM. In contrast, ventricular supernatant from late-embryonic (18-day E) chicks contained two forms of phosphodiesterase separable on DEAE-Sephacel: the same form as that seen at other ages, plus a cyclic AMP-specific form which was eluted at approx. 0.65 M-sodium acetate and was insensitive to stimulation by Ca2+-calmodulin. The ontogenetic changes in cyclic AMP phosphodiesterase activity in chick ventricular myocardium are consistent with reported ontogenetic changes in the steady-state contents of cyclic AMP in this tissue and suggest that this enzyme may be responsible for the changes that occur in this nucleotide during development of chick myocardium.
测定了鸡心室心肌发育过程中环磷酸腺苷磷酸二酯酶（3',5'-环核苷酸5'-核苷酸水解酶，EC 3.1.4.17）、腺苷酸环化酶[ATP焦磷酸裂解酶（环化），EC 4.6.1.1]的活性以及钙调蛋白含量。环磷酸腺苷磷酸二酯酶的比活性在早期胚胎中相对较低，在胚胎发育过程中增加约4倍，在孵化前达到最高值，然后在孵化后1周内下降约30%。相比之下，腺苷酸环化酶在胚胎发育过程中没有变化，但在孵化后1周内增加约50%。钙调蛋白含量在胚胎发育期间保持恒定，为9微克/克湿重，在孵化后1周下降至6微克/克湿重。对鸡心室上清液进行DEAE-琼脂糖凝胶柱层析显示，早期胚胎（胚胎第9天）和孵化后（孵化后第6天）的鸡中存在单一主要形式的环核苷酸磷酸二酯酶活性。这种酶形式在约0.27M醋酸钠处洗脱，可水解环磷酸腺苷和环磷酸鸟苷，对Ca2+-钙调蛋白的刺激敏感，钙调蛋白的表观Km约为1 nM。相比之下，胚胎后期（胚胎第18天）鸡的心室上清液含有两种可在DEAE-琼脂糖凝胶上分离的磷酸二酯酶形式：与其他年龄段相同的形式，以及一种环磷酸腺苷特异性形式，在约0.65M醋酸钠处洗脱，对Ca2+-钙调蛋白的刺激不敏感。鸡心室心肌中环磷酸腺苷磷酸二酯酶活性的个体发育变化与该组织中环磷酸腺苷稳态含量的报道个体发育变化一致，表明该酶可能是鸡心肌发育过程中该核苷酸发生变化的原因。
