Analysensystem zur Bestimmung der Aktivierungsenergie von enzymatischen Reaktionen

Hagelauer, U.; Faust, U.

doi:10.1515/bmte.1981.26.s1.291

Cited by 2 publications

(3 citation statements)

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“…Errors caused by deviations from linearity, which can be caused, for example, by impurities in the sample, were minimized by on-line recording of the photometric data, follqwed by their evaluation in a desk calculator (10). The N-acetylcysteine reactivation method was used for the determination of activation energy.…”

Section: Discussionmentioning

confidence: 99%

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The Catalytic Activity and Activation Energy of Creatine Kinase Isoenzymes

Hagelauer¹,

Faust²

1982

CCLM

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The catalytic activity and activation energy of an enzyme are obtained by measuring the rate of the enzymic reaction at two different temperatures. With the aid of the Arrhenius equation, these two parameters can be used to calculate a value proportional to the quantity of enzyme. Using this approach to investigate the isoenzymes of creatine kinase, it was shown that the activation energy increased in the order creatine kinase MM, MB, BB. Mixtures of the isoenzymes showed an apparent mean activation energy, which likewise could be determined using the Arrhenius equation.Ageing of the isoenzymes results in an exponential decrease of catalytic activity, accompanied by a continuous increase in activation energy, the calculated quantity of enzyme remaining constant. Inactivation is therefore not an all-or-nothing process; rather a stepwise inactivation of individual molecules must be assutiied. The results of these ageing experiments and observations by other authors suggest that a similar inactivation occurs in vivo. Die kataly tische Aktivität und Aktivierungsenergie der Kreatinkinase-IsoenzymeZusammenfassung: Durch die Messung der Geschwindigkeit einer enzymatischen Reaktion bei zwei verschiedenen Temperaturen erhält man die kataly tische Aktivität und die Aktivierungsenergie des Enzyms. Aus beiden läßt sich gemäß der Arrhenius*Gleich\mg eine der Enzymmenge proportionale Größe berechnen. Mit dieser Methode untersuchten wir die Isoenzyme der Kreatinkinase und stellten fest, daß die Aktivierungsenergie in der Reihenfolge Kreatinkinase MM, MB und BB ansteigt. Mischungen der Isoenzyme zeigen eine scheinbare, mittlere Aktivierungsenergie, die sich ebenfalls mit der Arrhemus-Gleichung bestimmen läßt.Bei der Alterung der Isoenzyme in vitro fällt die kataly tische Aktivität exporientiell ab. Daran gekoppelt ist eine kontinuierliche Zunahme der Aktivierungsenergie, die errechnete Enzymmenge bleibt dabei konstant. Die Inaktiviefung verläuft demnach nicht nach dem Alles-oder-Niehts Prinzip, vielmehr muß eine stufenweise Inaktivierung der einzelnen Moleküle angenommen werden. Die Ergebnisse dieser Alterungsversuche, sowie Beobachtungen anderer Autoren lasseh vermuten, daß auch in vivo eine vergleichbare Inaktivierung stattfindet. l ) Nonstandard abbreviations: CK: creatine kinase (ATP: creatine-phosphotransferase, EC 2.7.3.2). Greatine kinase MM, MB and BB: creatine kinase isoenzymes from striated muscle, heart and brain, respectively.

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Section: Discussionmentioning

confidence: 99%

“…also contains conversion factors (Nos [8][9][10][11]. for comparison of catalytic activities at different reaction temperatures (l l,12,13,14).…”

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The Catalytic Activity and Activation Energy of Creatine Kinase Isoenzymes

Hagelauer¹,

Faust²

1982

CCLM

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“…As shown by Hagelauer and Faust [6], the ageing of the enzyme is accompanied by variations of the apparer,t activation energy, u. Measurements during incubation of CK MM in a serum matrix at 37°C during 72 h showed a gradual increase of the apparent activation energy [lo]. A similar time is required to obtain complete in vitro modification of a comparable amount of CK MM, under the same conditions I21.…”

Section: Introductionmentioning

confidence: 99%

Indices for the age of the creatine kinase M-chain in the blood

Wevers

Hagelauer

Stein

et al. 1985

Clinica Chimica Acta

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SummaryThe apparent activation energy of the CK reaction as well as the Michaelis-Menten constants and the isoelectric point of CK MM can be used as indices for the mean age of the CK M-chain in the blood in vivo and in vitro. Modifications in the CK M-chain take place in vivo in the blood and in vitro in a serum matrix. Gradual increases in the apparent activation energy are also observed both in vivo and in vitro. It is confirmed that the modification in the CK M-chain causes a rise in the apparent activation energy, u.A gradual increase in apparent activation energy, due to the ageing process of the CK M-chain, was observed after myocardial infarction. A significantly increased value for u was observed at the time that total CK activity already had returned to reference values. In spite of the normal CK value, the apparent activation energy still indicated that there had been myocardial damage. The Michaelis-Menten constants for creatine phosphate and ADP are also influenced significantly by the modification in the M-chain. While the apparent activation energy increases, the Michaelis constants decrease in the order MM,, MM,, MM,. The Michaelis-Menten constants for both ADP and CrP can be used as an index for the mean age of the enzyme in the blood.The Michaelis-Menten constants for CrP and ADP show significant variations with the measuring temperature for virtually all CK MM forms.

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Analysensystem zur Bestimmung der Aktivierungsenergie von enzymatischen Reaktionen

Cited by 2 publications

References 1 publication

The Catalytic Activity and Activation Energy of Creatine Kinase Isoenzymes

The Catalytic Activity and Activation Energy of Creatine Kinase Isoenzymes

Indices for the age of the creatine kinase M-chain in the blood

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