de Meis Leopoldo, Arruda Ana Paula, Carvalho Denise P
Instituto de Bioquímica Médica, Universidade Federal do Rio de Janeiro, Cidade Universitária, 21941-590 RJ, Brasil.
Biosci Rep. 2005 Jun-Aug;25(3-4):181-90. doi: 10.1007/s10540-005-2884-7.
Enzymes are able to handle the energy derived from the hydrolysis of phosphate compounds in such a way as to determine the parcel that is used for work and the fraction that is converted into heat. The sarco/endoplasmic reticulum Ca(2+)-ATPases (SERCA) is a family of membrane-bound ATPases that are able to transport Ca(2+) ion across the membrane using the chemical energy derived from ATP hydrolysis. The heat released during ATP hydrolysis by SERCA may vary from 10 up to 30 kcal/mol depending on the SERCA isoform used and on whether or not a Ca(2+) gradient is formed across the membrane. Drugs such as heparin, dimethyl sulfoxide and the platelet-activating factor (PAF) are able to modify the fraction of the chemical energy released during ATP hydrolysis that is used for Ca(2+) transport and the fraction that is dissipated in the surrounding medium as heat. The thyroid hormone 3,5,3'-triiodo L: -thyronine (T(3)) regulates the expression and function of the thermogenic SERCA isoforms. Modulation of heat production by SERCA might be one of the mechanisms involved in the increased thermogenesis found in hyperthyroidism.
酶能够处理由磷酸化合物水解产生的能量，从而确定用于做功的部分和转化为热量的部分。肌浆网/内质网Ca(2+) - ATP酶（SERCA）是一类膜结合ATP酶，能够利用ATP水解产生的化学能跨膜转运Ca(2+)离子。SERCA水解ATP过程中释放的热量可能在10至30千卡/摩尔之间变化，这取决于所使用的SERCA同工型以及是否在膜上形成了Ca(2+)梯度。肝素、二甲基亚砜和血小板活化因子（PAF）等药物能够改变ATP水解过程中释放的用于Ca(2+)转运的化学能部分以及以热量形式消散在周围介质中的部分。甲状腺激素3,5,3'-三碘-L-甲状腺原氨酸（T(3)）调节产热SERCA同工型的表达和功能。SERCA对产热的调节可能是甲状腺功能亢进时产热增加所涉及的机制之一。
