Sulfonamide inhibition studies of two β-carbonic anhydrases from the ascomycete fungus Sordaria macrospora, CAS1 and CAS2

Figures & data

Table 1. Kinetic parameters for the CO₂ hydration reaction catalysed by the human cytosolic isozymes hCA I and II (α-class CAs) at 20 °C and pH 7.5 in 10 mM HEPES buffer and 20 mM NaClO₄, and the β-CAs CAS1 and CAS2 of Sordaria macrospora measured at 20 °C, pH 8.3 in 20 mM TRIS buffer and 20 mM NaClO₄.

Isozyme	Activity level	kcat	kcat/Km (s^−1)	KI (acetazolamide) (nM)
hCA I	Moderate	2.0 × 10^5	5.0 × 10^7	250
hCA II	Very high	1.4 × 10^6	1.5 × 10^8	12
CAS1	Low	1.2 × 10^4	1.30 × 10^6	445
CAS2	Low	1.3 × 10^4	1.21 ×	816

Inhibition data with the clinically used sulfonamide acetazolamide (5-acetamido-1,3,4-thiadiazole-2-sulfonamide) are also provided.

Table 2. Inhibition of human isoforms hCA I and hCA II, and of the β-class fungal enzymes CAS1 and CAS2 with sulfonamides 1–24 and the clinically used drugs AAZ–HCT.

Inhibitor/enzyme class	KI^a (nM)
	hCA I^b	hCA II^b	CAS1^c	CAS2^c
	α	α	β	β
1	28,000	300	361	386
2	25,000	240	144	3480
3	79^c	8	225	3630
4	78,500	320	47.1	6900
5	25,000	170	323	8720
6	21,000	160	241	7650
7	8300	60	43.2	7360
8	9800	110	79.6	9120
9	6500	40	580	12,000
10	7300	54	>50,000	23,500
11	5800	63	890	18,700
12	8400	75	3350	>50,000
13	8600	60	8650	48.1
14	9300	19	7215	280
15	5500	80	3160	143
16	9500	94	4520	92.5
17	21,000	125	>50,000	390
18	164	46	4435	3250
19	109	33	475	6760
20	6	2	363	9880
21	69	11	4550	4060
22	164	46	1985	25,200
23	109	33	282	>50,000
24	95	30	294	>50,000
AAZ	250	12	445	816
MZA	50	14	421	8140
EZA	25	8	440	3170
DCP	1200	38	1220	5790
DZA	50,000	9	360	742
BRZ	45,000	3	451	739
BZA	15	9	2115	410
TPM	250	10	414	673
ZNS	56	35	1820	1885
SLP	1200	40	1715	670
IND	31	15	4240	216
VLX	54,000	43	4425	3730
CLX	50,000	21	2513	857
SLT	374	9	3210	496
SAC	18,540	5959	5280	7075
HCT	328	290	3350	6680

^a Errors in the range of 5–10% of the reported data, from three different assays (data not shown).

^b Human recombinant isozymes, stopped flow CO₂ hydrase assay method, from Refs. [9,22–25].

^c Recombinant fungal enzyme, stopped flow CO₂ hydrase assay method, this work.

(a) Supuran CT. Structure-based drug discovery of carbonic anhydrase inhibitors. J Enzyme Inhib Med Chem 2012;27:759–72. (b) Scozzafava A, Menabuoni L, Mincione F, Supuran CT. Carbonic anhydrase inhibitors. A general approach for the preparation of water-soluble sulfonamides incorporating polyamino-polycarboxylate tails and of their metal complexes possessing long-lasting, topical intraocular pressure-lowering properties. J Med Chem 2002;45:1466–76. (c) Alterio VD, Fiore A, D’Ambrosio K, et al. Multiple binding modes of inhibitors to carbonic anhydrases: how to design specific drugs targeting 15 different isoforms? Chem Rev 2012;112:4421–68.

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