Controlling the highest lactate dehydrogenase activity known in nature

Area of Science:

• Marine Biology
• Biochemistry
• Fish Physiology

Background:

• Shipjack (Euthynnus pelamis) white muscle displays unique metabolic characteristics.
• Understanding the enzymatic basis of muscle function is crucial for fish physiology.

Purpose of the Study:

• To investigate the anaerobic and aerobic capacities of shipjack white muscle.
• To elucidate the roles and regulation of lactate dehydrogenase and alpha-glycerophosphate dehydrogenase.

Main Methods:

• Enzyme activity assays for lactate dehydrogenase and alpha-glycerophosphate dehydrogenase.
• Analysis of enzyme activity under varying temperature, pH, and creatine phosphate conditions.

Main Results:

• Shipjack white muscle possesses exceptionally high lactate dehydrogenase activity, indicating potent anaerobic glycolysis.
• Unusually high alpha-glycerophosphate dehydrogenase activity suggests a significant role in aerobic glycolysis.
• Enzyme activity is modulated by physiological conditions: high temperature, low pH, and low creatine phosphate favor anaerobic pathways, while low temperature, high pH, and high creatine phosphate favor aerobic pathways.

Conclusions:

• Shipjack white muscle is metabolically versatile, capable of both powerful anaerobic and significant aerobic glycolysis.
• Enzyme regulation by environmental and physiological factors allows adaptation to different activity states.
• These findings provide insight into the bioenergetics of active marine species.