nonenzymatic protein glycosylation backtitration assay the glycosylation of albumin in vitro as judged from the incorporation of du14cglucose into trichloroacetic acid tcaprecipitable material represents a time temperature and concentrationrelated process it is markedly increased by nacnbh3 a close correlation is observed between the radioactive data and the percentage of glycosylated albumin as measured by affinity chromatography the latter method however does not give information on the precise stoichiometry of the protein glycosylation the relative extent of protein glycosylation can also be estimated by a backtitration procedure the condensation of labelled dglucose with the protein being inversely related to its prior degree of glycosylation the backtitration assay was applied to plasma samples from normal and diabetic rats or human subjects and used to compare the glycosylation of albumin by distinct hexoses and hexosephosphates lglucose was found as efficient as dglucose in causing albumin glycosylation and hence could conceivably be used to investigate in vivo changes in the intrinsic properties of extracellular proteins secondary to their glycosylation