Purification and properties of mouse pyruvate kinases K and M and of a modified K subunit

The K4 and M4 isozymes of mouse pyruvate kinase were purified to homogeneity, and their physical, chemical, and kinetic properties were compared. The K isozyme is slightly larger, but a high degree of homology exists as evidenced by a similar amino acid composition, immunotitration value, and two-di...

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Bibliographic Details
Published in:Biochemistry (Easton) 1981-03, Vol.20 (6), p.1497-1506
Main Authors: Ibsen, Kenneth H, Chiu, Robert H. C, Park, Hae Ryun, Sanders, Dennis A, Roy, Srecko, Garratt, Kirk N, Mueller, Mark K
Format: Article
Language:English
Subjects:
Amino Acids - analysis
Animals
Enzyme Precursors
Immunodiffusion
Isoenzymes - analysis
Isoenzymes - metabolism
Kinetics
Male
Mice
Molecular Weight
Muscles - enzymology
Pyruvate Kinase - analysis
Pyruvate Kinase - metabolism
Spleen - enzymology
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Summary:The K4 and M4 isozymes of mouse pyruvate kinase were purified to homogeneity, and their physical, chemical, and kinetic properties were compared. The K isozyme is slightly larger, but a high degree of homology exists as evidenced by a similar amino acid composition, immunotitration value, and two-dimensional arginine peptide pattern after tryptic digestion. Also, the more active conformational form of the K isozyme has kinetic and chromatographic properties similar to those of the M isozyme. Only K subunit could be extracted with antibody from fresh spleen extracts, but this subunit can be cleaved to form a product with the mobility of the M subunit. The cleavage is accomplished by an endogenous enzyme and appears to be the first step in K-enzyme degradation. This product is called Kpm . KpmK hybrid could also be purified to homogeneity. This enzyme has the structure K2pmK2, and both types of subunit have activity. The Kpm form has a higher K0.5S value for phosphoenolpyruvate and a lower K0.5S value for ADP than does either the K or the M type. However, the Kpm and M subunits otherwise have very similar properties and it is speculated that the Kpm subunit is an M-type precursor.
ISSN:0006-2960
1520-4995
DOI:10.1021/bi00509a014