. Author manuscript; available in PMC: 2008 Jul 7.

Published in final edited form as: Biochemistry. 2006 Aug 29;45(34):10344–10350. doi: 10.1021/bi060746v

Table 3.

Substrate Specificity of OxlT and Its Derivatives

Sample ^a	Parent	R272K	R272C + MTSEA	K355C + MTSEA
	Residual [¹⁴C]Oxalate Transport (%)
No Addition	100	100	100	100
+ Oxalate	1 ± 0.1	9 ± 0.8	5 ± 1.4	3 ± 0.5
+ Malonate	34 ± 3.1	39 ± 5.9	80 ± 3.1	70 ± 8
+ Nitrate ^b	51 ± 10	36 ± 4.5	28 ± 4	11 ± 3
+ Formate	59 ± 4.4	55 ± 3.6	40 ± 1.6	7 ± 0.4
+ Glyoxylate	69 ± 6.1	69 ± 1.7	52 ± 1.3	64 ± 1.0
+ Bicarbonate ^b	80 ± 8.8	95 ± 6.6	72 ± 3.7	84 ± 4.2
+ Acetate	81 ± 6.5	72 ± 1.2	93 ± 2.0	45 ± 1.7
+ Lactate	82 ± 2.8	103 ± 2.7	119 ± 3.7	86 ± 4.3
+ Glycolate	88 ± 8.9	86 ± 1.9	95 ± 3.4	62 ± 3.4

Mean values ± SD from 3 separate experiments reporting relative accumulation of labeled oxalate by proteoliposomes for initial rate determinations, using 0.1 mM [¹⁴C]oxalate with potassium sulfate (no addition) or the potassium salt of the indicated competing substrates present at 10 mM.

Using assay buffer in which 50 mM MOPS/K plus 100 mM potassium gluconate replaced 50 mM potassium phosphate plus 100 mM potassium sulfate. Control experiments showed this substitution had no significant effect on OxlT function.