Table 2. Mn(II)–Ligand Internal Coordinates in the Cluster Models Used To Obtain the Computed Zero-Field Splitting Values.

internal coordinatea	WT OxDCb	WT OxDCc	WT OxDCd	W132F (model 1)e	W132F (model 2)f
Mn–O(Glu101)g	2.12	h		2.15	2.11
Mn–N(His95)	2.29			2.24	2.27
Mn–N(His97)	2.31			2.24	2.31
Mn–N(His140)	2.36			2.36	2.35
Mn–O(Wat1)	2.33			2.39	2.36
Mn–O(Wat2)	2.21			2.28	2.19
(Glu101)O–Mn–N(His95)	172.6			168.8	176.3
(Glu101)O–Mn–N(His97)	89.3			87.3	87.2
(Glu101)O–Mn–N(His140)	92.2			86.4	94.1
(Glu101)O–Mn–O(Wat1)	100.9			98.5	99.0
(Glu101)O–Mn–O(Wat2)	88.5			90.4	90.5
(His95)N–Mn–N(His97)	95.8			92.8	95.2
(His95)N–Mn–N(His140)	82.4			86.7	83.1
(His95)N–Mn–O(Wat1)	85.0			92.6	84.0
(His95)N–Mn–O(Wat2)	86.7			92.0	87.2
(His97)N–Mn–N(His140)	90.4			103.2	90.6
(His97)N–Mn–O(Wat1)	85.2			86.1	84.3
(His97)N–Mn–O(Wat2)	175.4			166.4	175.6
(His140)N–Mn–O(Wat1)	166.2			169.7	165.6
(His140)N–Mn–O(Wat2)	93.8			90.0	93.3
(Wat1)O–Mn–O(Wat2)	91.2			81.1	92.4
Mn–O(Glu280)	2.05	2.07	2.10
Mn–N(His273)	2.46	2.27	2.33
Mn–N(His275)	2.30	2.25	2.43
Mn–N(His319)	2.41	2.25	2.33
Mn–O(H)	2.00	2.19i	1.98
(Glu280)O–Mn–N(His273)	163.6	173.2	157.0
(Glu280)O–Mn–N(His275)	81.1	85.0	75.8
(Glu280)O–Mn–N(His319)	98.5	98.9	97.0
(Glu280)O–Mn–O(H)	116.0	90.2	116.8
(His273)N–Mn–N(His275)	83.7	88.5	81.5
(His273)N–Mn–N(His319)	78.2	85.1	82.6
(His273)N–Mn–O(H)	79.7	94.3	86.0
(His275)N–Mn–N(His319)	100.2	109.2	98.8
(His275)N–Mn–O(H)	139.7	148.5	158.5
(His319)O–Mn–O(H)	111.7	102.3	96.7

^aBond lengths (Å) and angles (°).

^bQM/MM-optimized structure with the bound hydroxide in the C-terminal Mn(II) center forming a hydrogen bond to a water molecule. This structure was obtained from the X-ray crystal structure of WT OxDC (1UW8) (Figure 7a,d).

^cQM/MM-optimized structure with water bound to the C-terminal Mn(II) center based on the X-ray crystal structure (1UW8) (Figure 7b).

^dQM/MM-optimized structure with hydroxide bound to the C-terminal Mn(II) center based on the X-ray crystal structure (1UW8) (Figure 7c).

^eQM/MM-optimized structure obtained from the X-ray crystal structure of the Co(II)-containing W132F OxDC variant.

^fQM/MM-optimized structure obtained from in silico substitution of the X-ray crystal structure of WT OxDC (1UW8).

^gBacillus subtilis residue numbering.

^hNot applicable.

ⁱMn(II)-bound water.