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. 2017 Feb 23;12(2):e0172712. doi: 10.1371/journal.pone.0172712

Fig 4. Expression and purification of soluble G. gallus β-keratins.

Fig 4

(A) Construction of expression vectors for recombinant Chr2_FK4, Chr25_FK25, and Chr27_FK12 β-keratins. (B) SDS-PAGE analysis of recombinant keratins expressed in E. coli, and purification of soluble Chr2_FK4 and Chr27_FK12 β-keratins. Lane M, molecular weight markers; lane 1, E. coli BL21 (DE3); lane 2, E. coli BL21 (DE3) (pET-28a_Chr2); lane 3, E. coli BL21 (DE3) (pET-28a_Chr25); lane 4, E. coli BL21 (DE3) (pET-28a_Chr27); S, supernatant; P, pellet. (C) Transmission electron microscope images of recombinant β-keratins. (D) Quantification of soluble Chr2_FK4 and Chr27_FK12 β-keratins using Kunitz and ninhydrin assays. Linear correlation between the absorbance at 280 nm and the concentration of purified β-keratins.