Fig 1.
Tyrosine-related substrates, reactions and enzymes involved in enzymatic browning in insects, together with subsequent non-enzymatic reactions.
Table 1.
Overview of reactions between different enzymes and substrates which occur (+).
Fig 2.
Color formation directly after grinding in MilliQ water and centrifugation of T. molitor, A. diaperinus and H. illucens.
Fig 3.
Effect of pH on specific oxidative enzyme activity (nmol mL-1s-1) of enzyme extracts from the larvae of T. molitor (A), A. diaperinus (B) and H. illucens (C).
L-DOPA (red), L-DOPA+H2O2 (orange), L-dopamine (light blue), L-tyrosine (green) or ABTS (purple) were used as substrates and buffer (dark blue) as negative control (n = 2, error bars represent absolute deviation).
Fig 4.
AEC fractionation pattern (black line) at 214 nm for T. molitor (A) and A. diaperinus (B).
The panels also report the increase of absorbance at 520 nm per day for each fraction, when assayed with L-DOPA (red) and L-tyrosine (green) (n = 2), error bars represent absolute deviation).
Table 2.
Reaction products formed after incubation of pooled fractions TI-V from T. molitor with substrates L-tyrosine and L-DOPA; + formed, × not found, = substrate constant, − substrates decreases, n/a not applicable.
Fig 5.
Native PAGE stained with 3 mM L-DOPA (left) showed active bands for extract of Tenebrio molitor (T), Alphitobius diaperinus (A) and Hermetia illucens (H).
Two pooled active fractions from the same insects were subjected to PAGE analysis (TIII, TIV, AIII, AIV, HIII and HIV). Numbering on the left highlights the bands excised and further subjected to proteomic analysis. A similar gel was stained with Coomassie (right).
Table 3.
Browning related proteins identified in T. molitor bands from native PAGE (Fig 4).