Table 1.
Kinetic Data for the Rate of Sugar Loss in a Maillard Reaction with Amine at 37 °C
| Sugar‡ | Amine‡ | Technique | pKa* (at 37 °C) |
pH | k
(M-1 h-1) |
k* (M-1 h-1) |
|---|---|---|---|---|---|---|
| R5P | Gly-gly | 1H NMR | 7.8 | 8.0 | 0.6 | 1.0 |
| R5P | L-Asn | 1H NMR | 8.6 | 8.0 | 0.35 | 1.8 |
| R5P | Gly | 1H NMR | 9.46 | 8.0 | 0.26 | 7.8 |
| R5P | L-Ala | 1H NMR | 9.7 | 8.0 | 0.07 | 3.6 |
| R5P | β-Ala | 1H NMR | 9.95 | 8.0 | 0.31 | 28 |
| R5P | L-NAcLys | 1H NMR | 10.25 | 8.0 | 0.20 | 36 |
| R5P | L-NAcArg | 1H NMR | 12.25 | 8.0 | 0.005 | 89 |
| R5P (2X) | L-NAcLys | 1H NMR | 10.25 | 8.0 | 0.63 | 113 |
| R5P | L-NAcLys | 1H NMR | 10.25 | 7.5 | 0.32 | 180 |
| R5P | L-NAcLys (0.5X) | LC/MS | 10.25 | 7.5 | 0.32 | 180 |
| Ribose | L-NAcLys | LC/MS | 10.25 | 7.5 | 0.021 | 11.8 |
| dR5P | L-NAcLys | 1H NMR | 10.25 | 7.5 | 0.015 | 10.7 |
| Deoxyribose | L-NAcLys | LC/MS | 10.25 | 7.5 | ~ 0 | ~ 0 |
‡
Sugar concentrations were 0.050 M and amine concentrations were 0.10 M except where noted.
*
Gly pKa at 37 °C obtained from a literature value while L-NAcArg was estimated from a literature value at 25 °C. pKa’s for Gly-gly, β-Ala, L-Ala, L-Asn, and L-NAcLys at 37 °C were determined by titration. The ribose and deoxyribose experiments contained equimolar amounts of inorganic phosphate.