Varfolomeev S D, Zaĭtsev S V, Il'ina M D, Berezin I V
Mol Biol (Mosk). 1975 Nov-Dec;9(6):893-902.
A detailed kinetic analysis has been performed of a multistep inactivation of chloroplasts. The kinetic model suggested involves the formation of chloroplast forms differing in stability and activity. A comparison of the kinetic model with the experimental data shows that the mechanism of inactivation of isolated pea chloroplasts consists of at least two forms displaying different activity in the Hill reaction and different stability in solution. The effect was studied of the nature of the buffer and destruction products on the kinetics of chloroplast inactivation in the process of "ageing". In phosphate buffer, where the concentration of phosphate exceeds 40 mM, the effect of the destruction products of chloroplasts on their inactivation is insignificant. The pH dependence on the inactivation kinetics suggests that the pH region from 6 to 9 affects only the rapid kinetic process resulting in the increase in the chloroplast activity; irreversible inactivation of chloroplasts is pH-independent. The temperature dependence of the irreversible inactivation kinetics has been studied and the activation parametres of this stage have been determined. Possible molecular mechanism of the limiting stages of the inactivation of isolated chloroplasts are discussed, which can explain the kinetic data obtained.
已对叶绿体的多步失活进行了详细的动力学分析。所提出的动力学模型涉及形成稳定性和活性不同的叶绿体形式。动力学模型与实验数据的比较表明，分离的豌豆叶绿体的失活机制至少由两种形式组成，它们在希尔反应中表现出不同的活性，在溶液中具有不同的稳定性。研究了缓冲液性质和破坏产物对叶绿体在“老化”过程中失活动力学的影响。在磷酸盐浓度超过40 mM的磷酸盐缓冲液中，叶绿体破坏产物对其失活的影响不显著。pH对失活动力学的依赖性表明，pH值在6至9的范围内仅影响导致叶绿体活性增加的快速动力学过程；叶绿体的不可逆失活与pH无关。研究了不可逆失活动力学的温度依赖性，并确定了该阶段的活化参数。讨论了分离叶绿体失活极限阶段可能的分子机制，这可以解释所获得的动力学数据。
