sion 4 General method for measuring sugars ntroduction to Medical Biochemistry CrABo- Session 4: A general method for measuring sugars INTRODUCTION common method for determining the concentration of sugars is to make use of the aldehiyde or ketone agents, therefore sugars” The diagram below shows a monosaccharide (glucose) with an aldehyde group on group on the individual monosaccharides. These functional groups can act as reducing monosaccharides which contain these groups are reterred to as “reduci carbon number one OH OH O OH OH has a red I DNS is a The reagent DNS (dinitrosalicylate) can be reduced to 3-amino-5-nitrosalicylate which brown colour with an absorbance maximum at 540 nm (see diagram below). Therefore common reagent used to measure sugars. It will be reduced by all reducing sugars and is specific to any particular monosaccharide such as glucose, fructose, or galactose OH OH 2 H20 NO2 No, No, DNS 3-amino-5-nitrosalicylate (red-brown colour) Key Learning Objectives Be able to determine the concentration of an unknown sucrose solution using a reducing sugar assay Be aware that the absorbance value of an unknown solution should be within the range of the assay’s standard curve Be able to calculate and express the concentration of a solution using different units; eg mmol. g. or percentage (%). Page 1 of 2
