Mitochondrial GTP-AMP phosphotransferase. 1. Purification and properties

Area of Science:

• Biochemistry
• Enzymology

Background:

• Mitochondria are key cellular organelles involved in energy production.
• GTP-AMP phosphotransferase plays a role in nucleotide metabolism.

Purpose of the Study:

• To purify and characterize GTP-AMP phosphotransferase from beef heart mitochondria.
• To investigate the enzyme's properties and potential inhibitors.

Main Methods:

• Purification involved freeze-thawing, acid/alkali treatment, and multiple chromatography steps.
• Enzyme homogeneity was confirmed by SDS-PAGE and isoelectric focusing.
• Crystallization was achieved using poly(ethylene glycol).

Main Results:

• GTP-AMP phosphotransferase was purified 116-fold with 24% yield.
• The crystalline enzyme exhibited a specific activity of 290 U/mg.
• Molecular weight was determined to be 26,000, with an isoelectric point of 9.8.

Conclusions:

• The study successfully purified and characterized GTP-AMP phosphotransferase.
• Amino acid composition and inhibitory profiles were elucidated.
• Guanosine(5')pentaphospho(5')adenosine was identified as a potent inhibitor.