Maillard reactions of ribose 5-phosphate and amino acids.

An important metabolite in nucleotide synthesis, ribose 5-phosphate (R5P) undergoes Maillard reactions at a rate significantly faster than most common sugars and sugar phosphates of its type. At pH = 8 and 37 degrees C, R5P reacts with amino acids to generate UV-absorbing compounds within hours and brownish compounds within a day. The increased rate can be attributed to the strategic location of the 5-phosphate group near the reactive C1 center. As expected, the rate of reaction is at least partially related to pKa of the attacking amine and it follows first-order kinetics in respect to amine (in the case of glycine). In terms of producing 280 nm absorbing compounds, the reaction order in respect to R5P was 1.5. The reaction mechanism appears to proceed through a 1-deoxyribosome intermediate. In reactions with proteins, R5P exhibits an ability to promote cross-linking.