Photochemical reactions of horseradish peroxidase compounds I and II at room temperature and 13 degrees K.
Some photochemical reactions of horseradish peroxidase compounds I and II (HRP-I and HRP-II, respectively) have been studied by electronic absorption spectroscopy over the temperature range 297 degrees K-10 degrees K. In glassy matrices below 80 degrees K HRP-I is rapidly converted to hrp-ii when irradiated with low power white light. The native enzyme and HRP-II are not photochemically active at these temperatures with low power irradiation. At room temperature the spontaneous decay of both HRP-I and HRP-II is catalyzed by irradiation with white light. It is shown that the photolysis is dependent upon light in the region 450-320 nm. It is concluded that the HRP-I and HRP-II conformations are closely related with only a low transition energy in the presence of electrons generated by the light. The conversion of HRP-II to HRP is accompanied by large conformational changes and so is inhibited at low temperatures.
D005615:Freezing; D005990:Glycerol; D007700:Kinetics; D010544:Peroxidases / Q000378:metabolism; D010777:Photochemistry; D010944:Plants / Q000201:enzymology*; D013053:Spectrophotometry; D013056:Spectrophotometry, Ultraviolet; D013696:Temperature; D013997:Time Factors; D014867:Water
D014867:Water; D010544:Peroxidases; D005990:Glycerol