A streamlined method for preparing split intein for NMR study.

•The method incorporates a circular permutation concept to efficiently prepare native split intein.•The method avoids the problem of aggregation of intein fragments and is insensitive to the ratio of the two intein fragments.•The method is applicable to other native and artificial split inteins with various split sites.•The assignment of NMR spectra of a native split intein is achieved.