STABILIZATION OF ENZYMES AGAINST THERMAL-STRESS AND FREEZE-DRYING BY MANNOSYLGLYCERATE

2-O-beta-Mannosylglycerate, a solute that accumulates in some (hyper)t hermophilic organisms, was purified from Pyrococcus furiosus cells, an d its effect on enzyme stabilization in vitro was assessed. Enzymes fr om hyperthermophilic, thermophilic, and mesophilic sources were examin ed, The thermostabilities of alcohol dehydrogenases from P. furiosus a nd Bacillus stearothermophilus and of glutamate dehydrogenases from Th ermotoga maritima and Clostridium difficile were improved to a signifi cant extent when enzyme solutions were incubated at supraoptimal tempe ratures in the presence of 2-O-beta-mannosylglycerate, but no effect o n the thermostability of glutamate dehydrogenase from P. furiosus was detected, On the other hand, there was a remarkable effect on the ther mal stabilities of rabbit muscle lactate dehydrogenase, baker's yeast alcohol dehydrogenase, and bovine liver glutamate dehydrogenase, which were used as model systems to evaluate stabilization of enzymes of me sophilic origin, For all of the enzymes examined and at the highest te mperatures tested, 2-O-beta-mannosylglycerate was a better thermoprote ctant than trehalose, The stabilizing effect exerted by 2-O-beta-manno sylglycerate on enzymes suggests a role for this compound as a protein thermostabilizer under physiological conditions, 2-O-beta-Mannosylgly cerate was also effective in the protection of enzymes against stress imposed by freeze-drying, with its protecting effect being similar to or better than that exerted by trehalose, The data show 2-O-beta-manno sylglycerate to be a potential enzyme stabilizer in biotechnological a pplications.