Glucose utilization in vertebrates as a molecular probe for the study of evolution

Area of Science:

• Biochemistry
• Evolutionary Biology
• Comparative Physiology

Background:

• Hexokinases are crucial enzymes in glucose metabolism.
• Understanding hexokinase isozyme diversity provides insights into evolutionary adaptations.
• Previous studies have hinted at variations in hexokinase across vertebrate classes.

Purpose of the Study:

• To characterize and compare hexokinase isozymic profiles across a wide range of vertebrate species.
• To investigate the evolutionary conservation and divergence of hexokinase enzymes in liver tissues.
• To correlate enzymatic properties with phylogenetic relationships.

Main Methods:

• Analysis of hexokinase isozymic patterns from liver tissue extracts of 68 vertebrate species.
• Biochemical characterization including kinetic and physicochemical properties of isolated isozymes.
• Comparative analysis of enzyme profiles across different vertebrate taxa.

Main Results:

• Significant diversity in liver hexokinase isozymic profiles was observed across 68 vertebrate species.
• Mammalian, turtle, and amphibian liver hexokinases exhibited high similarity.
• Avian, lizard, and snake liver hexokinases formed distinct, internally similar groups, differing from mammals and amphibians.
• Liver pyruvate kinase patterns mirrored hexokinase findings.
• Vertebrate muscle hexokinase systems were highly conserved, predominantly featuring hexokinase B.

Conclusions:

• Liver hexokinase isozyme profiles reflect vertebrate evolutionary history and relationships.
• Distinct evolutionary trajectories for hexokinase systems exist between different vertebrate lineages.
• The conserved muscle hexokinase B suggests a fundamental role across vertebrates.