A glycerate kinase gene (ST2037) from the hyperthermophilic crenarchaeon Sulfolobus tokodaii was cloned and expressed in Escherichia coli. The purified homodimeric protein (45 kDa) specifically catalyzed the formation of 2-phosphoglycerate with d-glycerate as substrate. The thermostable enzyme displayed maximum activity (over 20 min) at 90A degrees C and pH 4.5. The maximal activity was in the presence of Co2+. The MOFRL family glycerate kinase used AMP as phosphate donor with maximal activity towards GTP. These characteristics of the enzyme suggested its potential in the catalytic production of 2-phosphoglycerate.