. 2020 Apr 21;25(8):1933. doi: 10.3390/molecules25081933

Table 3.

Examples of inverse solvent isotope effects due to metal-bound water.

Enzyme Metal Cofactor	Varied Substrate/Condition	Inverse SKIE	Ref.
carbonic anhydrase C (esterase activity); Zn²⁺	p-nitrophenyl acetate	^D2O(k_cat/K_m) = 0.73	[22]
thermolysin; Zn²⁺	3-(2-furyl)acrolyl-Gly-Leu-NH₂ 3-(2-furyl)acrolyl-Gly-Ala-NH₂ 3-(2-furyl)acrolyl-Gly-Abu-NH₂ 3-(2-furyl)acrolyl-Gly-Val-NH₂ 3-(2-furyl)acrolyl-Gly-Nva-NH₂ 3-(2-furyl)acrolyl-Gly-Phe-NH₂ 3-(2-furyl)acrolyl-Gly-Leu-NH₂ 3-(2-furyl)acrolyl-Gly-Leu-Ala	^D2O(k_cat/K_m) = 0.80 ± 0.02 ^D2O(k_cat/K_m) = 0.80 ± 0.01 ^D2O(k_cat/K_m) = 0.73 ± 0.01 ^D2O(k_cat/K_m) = 0.76 ± 0.01 ^D2O(k_cat/K_m) = 0.73 ± 0.01 ^D2O(k_cat/K_m) = 0.73 ± 0.02 ^D2O(k_cat/K_m) = 0.69 ± 0.02 ^D2O(k_cat/K_m) = 0.72 ± 0.01	[23] [24] [24] [24] [24] [24] [24] [24]
stromelysin; Zn²⁺	pL 6.0 pL 7.5 pL 9.5	^D2O(k_cat/K_m) = 0.80 ± 0.03 ^D2O(k_cat/K_m) = 0.85 ± 0.06 ^D2O(k_cat/K_m) = 0.75 ± 0.02	[25] [25] [25]
desuccinylase; Zn²⁺	N-succinyl-L,L-diaminopimelate	^D2O(k_cat/K_m) = 0.62 ± 0.06	[26]
desuccinylase; Zn²⁺	N-succinyl-L,L-diaminopimelate	^D2Ok_cat = 0.78 ± 0.05	[26]
alcohol dehydrogenase; Zn²⁺	NADH NADD	^D2Ok_cat = 0.50 ± 0.05 ^D2Ok_cat = 0.58 ± 0.06	[27] [27]
alcohol dehydrogenase; Zn²⁺	pL 8.75, single turnover	^D2Ok_slow = 0.394 ± 0.005	[28]
malate synthase; Mg²⁺	[methyl-²H₃]acetyl-CoA	^D2O(k_cat/K_m) = 0.6 ± 0.1	[29]
prolyl hydroxylase 2; Fe²⁺	acidic basic	^D2Ok_cat = 0.91 ± 0.03 ^D2Ok_cat = 0.9 ± 0.1	[11] [11]
factor-inhibiting hypoxia-inducible factor; Fe²⁺	saturating CTAD, αKG CTAD αKG (high [CTAD]) αKG (low [CTAD])	^D2Ok_cat = 0.51 ± 0.07 ^D2O(k_cat/K_m) = 0.40 ± 0.07 ^D2O(k_cat/K_m) = 0.32 ± 0.08 ^D2O(k_cat/K_m) = 0.11 ± 0.03	[30] [30] [30] [30]
adenosine deaminase; Zn²⁺	adenosine 7,8-dihydro-8-oxoadenosine	^D2O(k_cat/K_m) = 0.77 ± 0.06 ^D2O(k_cat/K_m) = 0.45 ± 0.04	[18] [18]
AMP deaminase; Zn²⁺	AMP, no ATP	^D2O(k_cat/K_m) = 0.71 ± 0.07	[31]
	AMP, no ATP	^D2Ok_cat = 0.98 ± 0.04	[31]
	AMP, 0.1 mM ATP	^D2O(k_cat/K_m) = 0.79 ± 0.11	[31]
	AMP, 0.1 mM ATP	^D2Ok_cat = 0.75 ± 0.03	[31]
	2′-dAMP, no ATP	^D2O(k_cat/K_m) = 0.49 ± 0.04	[31]
	2′-dAMP, no ATP	^D2Ok_cat = 0.62 ± 0.02	[31]
	2′-dAMP, 0.1 mM ATP	^D2O(k_cat/K_m) = 0.34 ± 0.02	[31]
	2′-dAMP, 0.1 mM ATP	^D2Ok_cat = 0.63 ± 0.02	[31]
	8-Br-AMP, 0.1 mM ATP	^D2O(k_cat/K_m) = 0.33 ± 0.03	[31]
	8-Br-AMP, 0.1 mM ATP	^D2Ok_cat = 0.58 ± 0.03	[31]