Human glucose-6-phosphate dehydrogenase: primary structure and cDNA cloning

Area of Science:

• Biochemistry
• Molecular Biology
• Genetics

Background:

• Glucose-6-phosphate dehydrogenase (G6PD) is an X-chromosome-linked enzyme crucial for NADPH generation in erythrocytes.
• G6PD deficiency is associated with hemolytic anemia, a significant human health concern.

Purpose of the Study:

• To elucidate the complete amino acid sequence of human G6PD.
• To isolate and characterize cDNA clones encoding human G6PD.

Main Methods:

• Purification of G6PD from human erythrocytes.
• Automated and manual Edman degradation for amino acid sequencing.
• Synthesis of an oligonucleotide probe based on the amino acid sequence.
• Screening of human liver and hepatoma cDNA libraries using the probe.
• Southern blot analysis to confirm X-chromosome localization.

Main Results:

• The complete amino acid sequence of the human G6PD subunit (531 residues) was determined.
• Two cDNA clones, lambda G6PD-19 and lambda G6PD-25, were isolated from a human hepatoma library.
• Lambda G6PD-19 encoded 204 residues compatible with the enzyme's COOH-terminal portion.
• Lambda G6PD-25 encoded 362 residues of G6PD.
• Southern blot analysis confirmed that the G6PD cDNA hybridizes to a sequence on the human X chromosome.

Conclusions:

• The study successfully determined the amino acid sequence of human G6PD and isolated corresponding cDNA clones.
• The findings provide a molecular basis for understanding G6PD deficiency and its associated anemias.
• Confirmation of X-chromosome localization aids in genetic studies and diagnostics.