A Simple and Straightforward Method for Activity Measurement of Carbonic Anhydrases

Abstract

Carbonic anhydrase (CA) is an enzyme of high interest due to its high implications relative to the medical and environmental sectors. In the current paper, an enzyme assay for the determination of CA activity is proposed and it is characterized by its simplicity and high practicability. It permits the straightforward comparison of CAs performance in physiological conditions. The methodology and the theoretical background of the evaluation method are explained in detail. Moreover, the presumed advantages over alternative assays are discussed. The assay has proven to be particularly useful for the screening of CA activity with respect to their application in CO2, capturing processes for further utilization or storage.

Enhanced precipitation of magnesium carbonates using carbonic anhydrase

“…The tested concentrations for these additives ( c add ) ranged from 0.14 to 0.40 g L −1 for Scenedesmus obliquus and 0.035 to 0.2 g L −1 for CA. The pure CA values were chosen according to Power et al 27 and Fuchs et al 32 while Scenedesmus obliquus values were increased incrementally. The total suspended solids and the enzymatic activity of the culture was calculated for each experiments using microorganisms.…”

Comparison of Carbonic Anhydrases for CO2 Sequestration

“…Investigation of the effect of the CA addition on CO 2 hydration at different temperatures was made by monitoring the pH change in buffered solution due to the formation of carbonic acid using the method as described by Fuchs et al, 2021 [37]. The reactions were conducted in a temperature-controlled vessel and the temperature was varied between 25-50 • C. Frozen enzyme stock solutions were thawed, diluted to 0.1 mg mL −1 with 0.1 mol L −1 Tris-HCl (pH 7) and kept on ice until the measurement.…”

“…Hydratase activities at 25 • C were calculated using the logged pH data. HCO 3 − (mol L −1 ) was calculated according to the formula provided by Fuchs et al, 2021 [37]. Subsequently, HCO 3…”

“…The total turnover rate (µmol HCO 3 − L −1 s −1 ) of the blank measurement was subtracted from the measurements with CAs before the calculation of the turnover rate per mg enzyme (µmol HCO 3 − s −1 mg −1 ). To give the values in generally used units, a calibration curve with a standard enzyme (CA from bovine erythrocytes, Sigma-Aldrich, Taufkirchen, Germany) was used for conversion to Wilbur Anderson Units (WAU), as in Fuchs et al, 2021 [37].…”

“…The effect of the CA addition on CO 2 hydration at different temperatures was explored by applying the three CAs with the highest expression yields. A novel straightforward assay for the determination of CA activity was applied in this study, where measurement occurs close to industrial process conditions and temperatures [37]. The new assay allowed the characterization of CAs at temperatures exceeding 0 • C, which is unique concerning the commonly used Wilbur Anderson assay [38].…”