PMC

CD analysis of HDs. The structural transformation of HDs was promoted by the water‐deficient reagents 50% glycerol (B) and 50% TFE (C) compared to phosphate buffer (A). The secondary structure composition was estimated from CD spectra. Percentages of random coil (dark grey), turn (light grey), beta‐sheet (white) and α‐helix (red) are deduced from CD spectra using the CDPro program.

Interaction of HDs with LDH. A protein–protein interaction method, microscale electrophoresis, was employed to characterize the relationship between LDH and DrHD (A), CeHD (B), YlHD (C) and BnHD (D). The Kd value represents the dissociation constant indicating their affinity. The binding curve under normal conditions (phosphate buffer) is shown in dark blue, and the binding curve under 10 mM H₂O₂ treatment is shown in red (phosphate buffer supplemented with 10 mM H₂O₂).

Survival phenotype plate assay of E. coli recombinant strains under desiccation and oxidation. BL/DrHD, BL/CeHD, BL/YlHD and BL/BnHD are the expressing strains, and BL/pET28a recombinant carried an empty pET28a vector. Serial 10‐fold dilutions of OD‐standardized recombinant strains (OD ≈ 0.6) were spotted onto LB plates (6 μl) after desiccation for 10 days and 20 mM H₂O₂ treatment for 15 min; CK stands for untreated culture control.

Effect of desiccation on LDH aggregation and activity. LDH aggregation (A) and (B) activity on repeated desiccation. The molar ratio of LDH and tested proteins was 1:3 on aggregation assay, while at 1:2.5 molar ratio on enzyme activity measurement. These measurements were performed three times for each case, and their P‐values were calculated based on Tukey multiple comparisons using by R statistics. The letters ‘a’, ‘b’ and ‘c’ represent ‘not significantly different (P > 0.05)’, ‘significantly different (0.001 < P < 0.01)’ and ‘extremely significantly different (P < 0.001)’, respectively, compared to LDH alone.