EVALUATION OF THE CAPACITY OF GEL-ELECTROPHORESIS, STEADY-STATE AND TRANSIENT STATE ELECTROFOCUSING TO RESOLVE NATIVE HUMAN DES-ANGIOTENSINOGEN FROM ANGIOTENSINOGEN

The resolution of angiotensinogen (MW 56,800) linked to a decapeptide, angiotensin I (MW 1295), from the same protein without the decapeptide presents a challenging separation problem. Polyacrylamide gel electrophoresis at an optimized pH of 6.88 is unable to distinguish between the 2 proteins with statistical significance on the basis of size, but is able to discriminate between them with significance on the basis of their net charge difference. The proteins are separated in gel electrofocusing with a pI difference of about 0.1 pH unit. For practical purposes, neither the charge separation by gel electrophoresis nor that by steady-state electrofocusing seems sufficiently convenient. By contrast, transient state electrofocusing provides a ready means for their separation.