Activity and anion inhibition studies of the α-carbonic anhydrase from Thiomicrospira crunogena XCL-2 Gammaproteobacterium

BIOORGANIC & MEDICINAL CHEMISTRY LETTERS

卷:25

Article

Mahon, Brian P.¹  Diaz-Torres, Natalia A.¹  Pinard, Melissa A.¹  Tu, Chingkuang¹  Silverman, David N.²  Scott, Kathleen M.³  McKenna, Robert¹ 

[1] Univ Florida, Dept Biochem & Mol Biol, Coll Med, Gainesville, FL 32610 USA

[2] Univ Florida, Dept Pharmacol & Therapeut, Coll Med, Gainesville, FL 32610 USA

[3] Univ S Florida, Dept Integrated Biol, Tampa, FL 33620 USA

关键词: Thiomicrospira crunogena XCL-2;    alpha-Carbonic anhydrase;    Anions;    Mesophile;    CO2 hydration;   

DOI  :  10.1016/j.bmcl.2015.05.001

来源: Elsevier

【 摘 要 】

Thiomicrospira crunogena XCL-2 expresses an alpha-carbonic anhydrase (TcruCA). Sequence alignments reveal that TcruCA displays a high sequence identity (>30%) relative to other alpha-CAs. This includes three conserved histidines that coordinate the active site zinc, a histidine proton shuttling residue, and opposing hydrophilic and hydrophobic sides that line the active site. The catalytic efficiency of TcruCA is considered moderate relative to other alpha-CAs (k(cat)/K-M = 1.1 x 10(7) M-1 s(-1)), being a factor of ten less efficient than the most active alpha-CAs. TcruCA is also inhibited by anions with Cl-, Br-, and I- , all showing K-i values in the millimolar range (53-361 mM). Hydrogen sulfide (HS-) revealed the highest affinity for TcruCA with a K-i of 1.1 mu M. It is predicted that inhibition of TcruCA by HS- (an anion commonly found in the environment where Thiomicrospira crunogena is located) is a way for Thiomicrospira crunogena to regulate its carbon-concentrating mechanism (CCM) and thus the organism's metabolic functions. Results from this study provide preliminary insights into the role of TcruCA in the general metabolism of Thiomicrospira crunogena. (C) 2015 Elsevier Ltd. All rights reserved.

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