MEASUREMENT OF AVAILABLE LYSINE USING THE GUANIDINATION REACTION

Available lysine with its free .epsilon.-amino group can be chemically converted to homoarginine by means of a guanidination reaction using methylisourea (MIU). Various factors that can affect this reaction were investigated. For milk protein optimum conditions were pH 10.8 for 96 h at 20.degree. C with a MIU concentration of 0.5M. Other protein sources had a different optimum pH for the guandination reaction. Addition of various carbohydrate sources and amounts did not interfere with the quantitation of available lysine.