Table 2.

Thermostable CAs and their characteristic features.

Sl. No.	Enzyme	Organism	Class	Characteristic features	References
1.	SspCA	Sulfurihydrogenibium yellowstonense. YO3AOP1	α	Dimer, Stable at high temperatures (70°C for 3 h) Optimum working condition–95°C, pH 9.6	Capasso et al., 2012
2.	Saz CA	Sulfurihydrogenibium azorense	α	Dimer, Half-life at 70°C is 8 days and 53 days at 50°C. Alkalistable (pH 9.6)	De Luca et al., 2013; Russo et al., 2013
3.	TaCA	Thermovibrio ammonificans	α	77 days of half-life at 60°C, tetramer	Jo et al., 2014
4.	PmCA	Persephonella marina EX-H1	α	88 days of half-life at 100°C, Dimer	Jo et al., 2014; Kanth et al., 2014
5.	Cab CA	Methanobacterium thermoautotrophicum	β	Tetramer Optimal CO2 hydration activity at 75°C	Smith and Ferry, 2000
6.	MtCam (aerobically purified)	Methanosarcina thermophila	γ	Optimally active at 55°C and displayed 15 min of stability at 75°C, Activity doubles when zinc is replaced by cobalt	Alber and Ferry, 1994
7.	MtCam (anaerobicaly purified)	Methanosarcina thermophila	γ	NA	Tripp et al., 2004
8.	MtCam (expressed in M. acetivorans)	Methanosarcina thermophila	γ	Fe2+ present at active site enhances its activity	MacAuley et al., 2009
9.	BhCA	Bacillus halodurans	α	Thermo-alkali-table (pH 6–11), gets stimulated in the presence of SOx, stable with EDTA	Faridi and Satyanarayana, 2016a
10.	ApCA	Aeribacillus pallidus	γ	Thermo-alkali-stable (pH 8–11), stable in the presence of SOx and NOx	Bose and Satyanarayana, 2016