We describe a new and improved enzymatic assay for determining the con
centration of D-mannose in sera. Serum D-glucose is selectively conver
ted to glucose-6 phosphate with the highly specific thermostable gluco
kinase (EC 2.7.1.2) from Bacillus stearothermophilus. The anionic reac
tion products and excess substrates are removed by a rapid and simple
anion-exchange chromatography step in microcentrifuge spin columns. D-
Mannose in the glucose-depleted sample is then assayed spectrophotomet
rically by using coupled enzymatic reactions. The quantitative elimina
tion of glucose from the serum samples allowed the accurate and reprod
ucible assay of serum mannose in,the 0-200 mu mol/L range. Recovery of
mannose added to serum (5-200 mu mol/L) was 94% +/- 4.4%. The intraas
say CV was 6.7% at 40 mu mol/L mannose (n = 5; 39.6 +/- 1.6 mu mol/L)
and 4.4% at 80 mu mol/L (n = 11; 75.0 +/- 1.8 mu mol/L); the interassa
y CV at these concentrations was 12.2% (n = 7; 36.9 +/- 2.1 mu mol/L)
and 9.8% (n = 7; 74.2 +/- 2.7 mu mol/L), respectively. Sera from 11 he
althy human volunteers contained an average of 54.1 +/- 11.9 mu mol/L
mannose (range 36-81 mu mol/L).