Chemical and immunological characteristics of four different L‐asparaginase preparations

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Abstract
We studied the differences in protein composition and immunologic reactivity of two E. coli‐derived L‐asparaginase (1‐Asp) preparations (I and II), Erwinia‐Asp (III) and PEG‐modified E. coli 1‐Asp (IV). On gel filtration, each of preparations I‐III showed three major peaks at 100, 270 and 460 KD, all with enzyme activity, whereas PEG‐Asp showed peaks at 35 and 220 KD. On SDS‐PAGE one major subunit could be identified at 32 KD (I and II) or 40 KD (III), whereas PEG‐modified 1‐Asp could only be detected by lowering the polyacrylamide concentration and gave a single band above 200 KD. Using a polyclonal rabbit antibody generated against preparation I, only the E. coli 1‐Asp preparations (I and II) formed precipitin lines on Ouchterlony double diffusion. After freezing and thawing, preparation IV also reacted with this antibody. In sera from patients treated with preparation I, antibodies (detected by ELISA) reacted with preparations I and II but not with preparations III and IV. These results indicate that Erwinia‐Asp (III) and PEG‐Asp (IV) are distinct from E. coli preparations (I and II) by molecular weight and immunological behavior. They also provide an experimental rationale for the use of Erwinia‐Asp as well as PEG‐Asp in E. coli Asp‐sensitized patients.