Crystalline 3-phospho-d-glycerate kinase from horse muscle.

The research paper discusses the isolation of a crystalline form of phosphoglycerate kinase enzyme from horse muscle. The researchers describe an efficient isolation procedure while highlighting the enzyme’s properties.

Enzyme Isolation and Identification

• The researchers have successfully isolated phosphoglycerate kinase in its crystalline form from horse muscle. This isolation was achieved by following a convenient procedure which yielded a uniform enzyme of specific activity 700 units/mg at 30 degrees Celsius.
• They identified the enzyme as monomeric, meaning it is a single molecular unit, and determined its molecular weight to be 47,000.

Enzyme Activity and Reactivity

• The protein which forms the enzyme has eight cysteine residues. Two cysteine residues were found to reactivity rapidly with Nbs21, causing a subsequent loss of catalytic activity.

Previous Studies and Motivation for Current Research

• Scholars have previously isolated this enzyme from various sources including yeast, rabbit muscle, chicken muscle, and human erythrocytes. However, this work is specific to horse muscle.
• Various purification methods have been reported leading to enzymes approaching molecular homogeneity. These purification methods were executed on rabbit muscle and chicken muscle.
• Crystalline material being isolated from human erythrocytes, yeast, and rabbit muscle spurred the researchers to investigate this enzyme in horse muscle.
• Earlier crystallographic work done on phosphoglycerate kinase from horse muscle aroused mechanistic interest in the enzyme, motivating the researchers to not only perform a simplified isolation procedure but also examine some properties of the crystalline material from horse muscle.