Table 2.

Purification results and biophysical characteristics of purified IMP variants.

Characteristic\Enzyme	IMP-1	IMP-1-S115T	IMP-1-S119T	IMP-1-S115T-S119G
Relative In-Cell Expression Level (%)	100	95	54	83
Concentration After Purification (μM)	93.7	80.4	47.3	52.9
Yield of Purified Enzyme from 1 L Culture (mg)	5.2	4.2	1.3	3.6
Molecular Mass (measured)	25,112	25,125	25,082	25,096
Molecular Mass (calculated) 1	25,112.7	25,126.7	25,082.7	25,096.7
Zinc Content	2.2 ± 0.2	2.1 ± 0.2	2.1 ± 0.2	2.3 ± 0.1
Secondary Structure Elements: 2
α Helix (%)	37	37	37	37
β Sheet (%)	26	26	26	26
Random Coil (%)	38	38	38	38
Melting Temperature (°C) 3	73.5 ± 0.1	77.0 ± 0.1	72.1 ± 0.1	75.7 ± 0.1

¹ The molecular masses were calculated with the Compute pI/Mw program [25]. ² Percentages are as output by the DichroWeb [27,28] program K2D. Due to rounding, they add up to be 101%. ³ Melting temperatures ± errors are the result of nonlinear fitting to the normalized data in Prism 7.