Cyamopsis tetragonoloba annexin-1 gene (AnnCt1) is up-regulated under oxidative stress, and its protein has calcium-binding and an antioxidant property in-vitro.

Plant annexins play a crucial role in lowering the production of reactive oxygen species in response to environmental conditions. To study the role the guar Annexin-1 gene, designated as AnnCt1, was isolated from the developing seeds (30DAF) tissue of guar. The primary sequence of 951 bp AnnCt1 nucleotide encodes for a 316-amino-acid with a predicted molecular mass of 35.74 kDa and 6.07 theoretical pI. It shows sequence homology and evolutionary relationships with higher plant annexins. The expression of the AnnCt1 transcript has increased after being exposed to H₂O₂. The far UV-CD spectra of the purified rAnnCt1 protein revealed the presence of significant α-helices and showed 60.02 ± 5 °C of thermal stability. Decreasing intrinsic fluorescence intensity and increasing α-helices CD spectrum of the rAnnCt1 protein suggested its Ca²⁺-binding property in-vitro. According to various performed bioassays, purified rAnnCt1 protein scavenges ABTS^•+ radicals, helps in the prevention of gDNA oxidation caused by Fenton's reagent's hydroxyl radicals (OH^•), and improves the viability of recombinant E. coli cells under oxidative stress. Our findings imply oxidative responsive AnnCt1 gene encoding for Annexin-1 protein possesses antioxidant and Ca²⁺-binding property in-vitro. [ABSTRACT FROM AUTHOR]