Activation of human α-carbonic anhydrase isoforms I, II, IV and VII with bis-histamine schiff bases and bis-spinaceamine substituted derivatives

Figures & data

Scheme 1. General synthetic route for the synthesis of the bis-histamine Schiff bases and bis-spinaceamine substituted compounds (incorporating the fused imidazole ring system).

Table 1. CA activation data with bis-histamines H1-H4 and bis-spinaceamines SPH(1, 2 and4) and histamine(HST) as a standard activator, by a stopped-flow CO₂ hydrase assay¹³.

	KA (µM)^a
Compound	hCA I	hCA II	hCA IV	hCA VII
H1	4.73	42.1	3.96	9.02
H2	6.15	30.7	3.28	18.7
H3	18.4	25.9	10.9	21.3
H4	7.13	20.3	3.45	0.085
SPH1	10.2	8.21	32.7	0.032
SPH2	6.29	6.15	8.12	0.039
SPH4	9.87	19.2	2.37	0.035
HST	2.10	125	4.03	37.6

^a Mean from 3 different determinations (errors in the range of 5–10% of the reported values, data not shown).

Khalifah RG. The carbon dioxide hydration activity of carbonic anhydrase. I. Stop-flow kinetic studies on the native human isoenzymes B and C. J Biol Chem 1971;246:2561–73.

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