Depletion of phosphatidyl-glycerol head-group induces changes in oxygen evolution and protein secondary struc-tures of photosystem Ⅱ

The techniques of oxygen electrode polarogra-phy and Fourier transform infrared (FT-IR) spectroscopy were employed to explore the roles of polar head-group of phosphatidylglycerol (PG) molecules in the functional and structural aspects of photosystem Ⅱ (PS Ⅱ) through enzymatic approach. It was shown that the depletion of PG by treatment of phospholipase C (PLC) on PS Ⅱ particles caused the inhibition of oxygen evolving activity in PS Ⅱ. This effect also gave rise to changes in the protein secondary structures of PS Ⅱ, that is, an increase in a-helical conformation which is compensated by the loss of p-strand structures. It revealed that the head-group of PG molecules plays an important structural role in the maintenance of normal structure of PS Ⅱ proteins, which is required to maintain the appropriate physiological activity of the PS Ⅱ complex such as the oxygen evolving activity. It is suggested that there most probably exist hydrogen-bonding interactions between PG molecules and PS Ⅱ proteins.

Depletion of phosphatidylglycerol head-group induces changes in oxygen evolution and protein secondary structures of photosystem II

The techniques of oxygen electrode polarography and Fourier transform infrared (FT-IR) spectroscopy were employed to explore the roles of polar head-group of phosphatidylglycerol (PG) molecules in the functional and structural aspects of photosystem II (PS II) through enzymatic approach. It was shown that the depletion of PG by treatment of phospholipase C (PLC) on PS II particles caused the inhibition of oxygen evolving activity in PS II. This effect also gave rise to changes in the protein secondary structures of PS II, that is, an increase in α-helical conformation which is compensated by the loss of β-strand structures. It revealed that the head-group of PG molecules plays an important structural role in the maintenance of normal structure of PS II proteins, which is required to maintain the appropriate physiological activity of the PS II complex such as the oxygen evolving activity. It is suggested that there most probably exist hydrogen-bonding interactions between PG molecules and PS II proteins.