The reaction centers of PSI and PSII in chloroplast thylakoids are known to be a main site of ROS generation under oxidative stress [1] that induced a significant damage to cell biological structures and physiological-biochemical processes run in them [2]. ROS, accumulating in chloroplasts [3] affects first to PS II and its main manganese complex-Mn4O5Ca-cluster [4, 5]. The fall of PS II activity is regards to result of balance disturbance between its restoration and damage since in intact cells these processes are take place simultaneously [6, 7]. The oxygen of main triplet state (3O2) is excited to singlet state (1O2) by chlorophyll of reaction centers of triplet excited state (3P680*) [8]. The target of ROS is known to be D1 protein that is one of subunit of PS II RC, that catalyzed of water splitting and realized of primary functions of charge separation and chlorophyll electron of reaction centers separation [9]. The D1 protein degradation at definite conditions may be triggered by long lived oxidative forms such as P680+ (first donor and Tyr-Z+) and take place at oxygen absence [10]. Degradation and re-synthesis of D1 protein is a process significantly faster compare to other thylakoid proteins and it is a reason of impossibility to detect of new synthesized proteins to restoration of photosynthetic activity [6, 11, 12, 13]. The inhibitor of protein synthesis is widely used in this connection. Chloramphenicol is one from there which connecting to great subunit of 70S ribosome has blocked its peptidyl-transferase activity [12]. In present work the damage mechanism of electron transport chain of PS II under increased content of ROS and its connection with D1 protein degradation were investigated.