Figure 2

Reactivity of DEH. (A) Reactivity of DEH with amino acids and ammonium salts. DEH (1% w/v) was incubated in the presence of 50 mM amino acids and ammonium salts at 30 °C for 24 h, with the exception of Tyr, Trp, and Asp, which were evaluated at 1.0, 20, and 12.5 mM because of their insolubility. (B) Reactivity of DEH with nutrient-rich mixtures. Each of the indicated nutrient mixtures [2.0% (w/v)] or 50 mM AS [(NH₄)₂SO₄] was incubated at 30 °C for 22 h in the presence (+) or absence (−) of 1% (w/v) DEH. Tryptone and Yeast extract were from Nacalai Tesque; Bacto Tryptose, Tryptone Peptone, Bact Yeast Extract, and Soytone Peptone were from Becton, Dickinson and Company; and NZ Amine Type A was from Wako. (C) Reactivity of NH₄Cl with alginate metabolites. The metabolites of alginates [1% (w/v) DEH, 50 mM 2-keto-3-deoxy-d-gluconate, 50 mM 2-keto-3-deoxy-phosphogluconate, or 1% (w/v) oligoalginate] were incubated in the presence (lane 2) or absence (lane 3) of 50 mM NH₄Cl at 30 °C for 23 h. Lane 1, authentic compounds [5.0 μL; 1% (w/v) DEH, 50 mM 2-keto-3-deoxy-d-gluconate, 50 mM 2-keto-3-deoxy-phosphogluconate, 1% (w/v) oligoalginate]. (A–C) Samples (5.0 µL) were spotted, developed, detected, and visualized using the sulfate (left) and thiobarbituric acid (right) methods. KDG, 2-keto-3-deoxy-d-gluconate. KDPG, 2-keto-3-deoxy-phosphogluconate.