Difference between revisions of "Part:BBa K2547000"

Revision as of 11:28, 13 October 2018

Carbonic anhydrase 2

This part is the coding sequence (CDS) of wild-type carbonic anhydrase (CA2), because Carbonic Anhydrase II (CA2) is a metalloenzyme that can efficiently catalyze the formation of HCO3- and H+ from CO2 and H2O. The reaction catalytic efficiency is extremely high, the reaction rate is extremely fast, and a histidine tag (His-Tag) is attached to the coding sequence (CDS) to facilitate the purification of carbonic anhydrase protein.

Sequence and Features

We first synthesized the sequence of human carbonic anhydrase CA2, and then cloned it into the expression vector pET-30a(+), and identified the correctness of the obtained recombinant vector by restriction enzyme digestion and sequencing (Fig. 1 and Fig. 2).

Fig. 1 Map of CA2-WT recombinant vector

Fig. 2 Agarose Gel Electrophoresis of CA2-WT recombinant plasmid and its identification by enzyme digestion. Lane M: DL marker; Lane 1: CA2-WT recombinant plasmid; Lane 2: enzyme digestion band of CA2-WT digested by MluⅠ, the length was 1028 bp (the arrow indicated).

Induced expression of CA2-WT

The CA2-WT expression plasmid was transformed into E. coli BL21 (DE3), and the cultured liquid was subjected to IPTG-induced CA2 expression, and the bacterial solution was sonicated, followed by SDS-PAGE and Western Blot(Fig. 3 and Fig. 4) .It shows that the size of CA2 is 30.6 kDa, which is compared with Marker. The position indicated by the arrow in the figure is the CA2 band. It can be seen from lanes 1 and 2 in the figure that the IPTG condition is significantly induced. The expression of CA2, and it can be seen from lanes 3-6, that the induced expression of CA2 is mainly expressed in a soluble form in the supernatant of the bacterial liquid.The above results indicate that we successfully obtained E. coli which expresses CA2.

    

Fig. 3 SDS-PAGE analysis for CA2 cloned in pET-30a(+) and expressed in BL21(DE3) strain.

    

Fig. 4Western blot analysis for CA2 cloned in pET-30a(+) and expressed in BL21(DE3) strain.

Purification of CA2-WT

After confirming that CA2 can be induced by E. coli BL21 (DE3), we will further purify the crude protein extract by nickel column purification to obtain purified CA2 protein. The results in the figure (Figures 5 and 6) illustrate that we have obtained a higher purity CA2 protein.

    

Fig. 5 CA2 was purified with Ni column; fractions were analyzed by SDS-PAGE. Lane M: Protein marker; Lane 1: Supernatant after cell lysate centrifugation; Lane 2: Flow through; Lane 3: Wash with 50mM Tris, 150mM NaCl, 20 mM Imidazole, pH 8.0; Lane 4: Elute with 50mM Tris, 150mM NaCl, 50 mM Imidazole, pH 8.0; Lane 5: Elute with 50mM Tris, 150mM NaCl, 500 mM Imidazole, pH 8.0.

    

Fig. 6 SDS-PAGE and Western blot analysis of CA2. Lane 1: Positive control (BSA); Lane 2: purified CA2; Lane 3: Purified CA2.