EFFECTS OF CALCIUM-IONS ON ADENINE-NUCLEOTIDE TRANSLOCASE FROM CARDIAC-MUSCLE
EFFECTS OF CALCIUM-IONS ON ADENINE-NUCLEOTIDE TRANSLOCASE FROM CARDIAC-MUSCLE
复制标题
DOI：
10.1016/0022-2828(76)90069-9
复制
发表时间：
1976-01-01
影响因子：
5
通讯作者：
NEWSHOLME, EA
中科院分区：
文献类型：
--
作者：
BEIS, I;NEWSHOLME, EA
与来自肝脏的系统相比，在大鼠和鸽子心脏线粒体中发现了相似性。特别地，外部ADP的Km非常低，即，约7 μ M。在0.001-10 μ M范围内的Ca 2+浓度不影响易位酶[T]系统的最大活性（其通过跟踪腺嘌呤核苷酸[AN]穿过线粒体膜的交换来测量）或系统对ADP或ATP的Km。因此，改变几种关键代谢酶和肌原纤维ATP酶活性的肌浆Ca 2+浓度变化不太可能影响T.然而，较高浓度的Ca 2+（高达400 μ M）显著增加了AN的交换。心肌线粒体在线粒体膜中具有对Ca 2+的高亲和力结合位点，其结合高达300 nmol Ca 2 +/g心肌。如果ANT和对Ca ~（2+）的高亲和力位点相邻（或相同），则较高浓度的Ca ~（2+）对T的影响在控制心肌中的易位率方面将是相当重要的。
Similarities were found in rat and pigeon heart mitochondria compared to the system from liver. In particular, the Km for external ADP is very low, i.e., about 7 .mu.M. The maximum actvity of the translocase [T] system, which was measured by following the exchange of adenine nucleotides [AN] across the mitochondrial membrane, or the Km of the system for ADP or ATP were not affected by Ca2+ concentration in the range 0.001-10 .mu.M. Consequently, the concentration change in sarcoplasmic Ca2+ that modifies the activities of several key metabolic enzymes plus the myofibrillar ATPase was unlikely to affect the activity of the T. However, higher concentrations of Ca2+ (up to 400 .mu.M) increased considerably the exchange of the AN. Heart muscle mitochondria possess high affinity binding sites for Ca2+ in the mitochondrial membrane, which bind up to 300 nmol Ca2+/g of heart muscle. If the ANT and the high affinity sites for Ca2+ were adjacent (or identical), the effects of the higher concentrations of Ca2+ on the T would be of considerable importance in control of the rate of translocation in heart muscle.