UDPglucose 4-epimerase from Saccharomyces fragilis: desensitization with heat.

The allosteric kinetics exhibited by UDP glucose 4-epimerase from $\text{Saccharomyces fragilis}$ changes over to a normal hyperbolic kinetics when the enzyme is heated at 41° for 2 mins. The native enzyme is completely insensitive to inhibition by UMP in the allosteric region. The desensitized enzyme is however, strongly inhibited by UMP at this low concentrations. Apparently, desensitization by heat converts the enzyme to its ultimate catalytic form.