Methylene tetrahydrofolate thermolabile

Kang and coworkers (1991) reported a variant of methylene-tetrahydrofolate reductase, in which cytosine is replaced by thymidine, resulting in a change of alanine to valine, in people who were hyperhomocysteinemic (Section 10.3.4.2). The variant enzyme is thermolabile (i.e., it is unstable to heating to about 40° to 45°C), and subjects who are homozygous for the thermolabile enzyme have about 50% of normal enzyme activity in tissues. Not only is the enzyme labile on moderate heating in vitro, but it is also unstable in... 

Methylene-tetrahydrofolate reductase is a flavoprotein. There is some evidence that riboflavin also stabilizes the thermolabile variant tmd that riboflavin supplements may lower plasma homocysteine in people who tue homozygous for the vtiriant enzyme (McNulty et al., 2002). 

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