... the E a of inactivation and the temperature at which the enzyme starts inactivating at a measurable rate increasefrom the apoenzyme to the Mn2þ-containing enzyme, loss of the metal cofactor ... Numata, K., Hayashi-Iwasaki, Y. , Kawaguchi, J., Sakurai, M.,Moriyama, H., Tanaka, N. & Oshima, T. (2001) Thermostabiliza-tion of a chimeric enzyme by residue substitutions: four amino acidresidues ... does not appear to besignificant. Inactivation was accompanied by heavyaggregation at this enzyme concentration, and the differencein inactivation rate between the two samples probablyresults...