Lipoxygenase in Adaptation of the Neurospora crassa Cells to Temperature Stress

The adaptation of the N. crassa lipoxygenase (LOX) in response to heat (45°C) and cold (4°C) shock was studied. The difference was revealed in the dynamics of the LOX activity depending on the growing conditions of the mycelium. After incubation of the surface culture at 45°C, a gradual increase in the specific activity of the enzyme was observed with maximum at 2–3 h, followed by a subsequent decrease to the initial level. Under the same conditions, in a submerged culture, a decrease in the LOX activity was observed after 5 min; however, after 1 h of incubation, the enzyme activity also reached the initial level. The sensitivity of the N. crassa LOX to elevated temperatures is very high, since it is noted only in a narrow temperature range: the effect was detected at 45^oC; however, the enzymatic activity did not change in the culture incubated at 42°C, but, on the other hand, LOX was completely inactivated in the mycelium at 48°C. When the fungal cells were exposed to cold, the specific LOX activity increased after 1 h, then decreased to the initial level (2–3 h) and increased again, reaching a maximum after 18 h. When two stress factors, cold and starvation, acted simultaneously on the N. crassa cells, the treatment with cold had a decisive effect on the LOX activity, which was especially noticeable after 8 h of incubation.