Very low-level expression of hepatitis B virus (HBV) preS1 with the native-type N-termimls hampered the biochemical and functional studies on its myristoylation. In the present study, the fusion HBV preS I with the native-type N-terminus and a His6-Tag fused to C-terminus (HBV preS1-HT) was highly expressed in Escherichia coli. This was due to an introduced mutation of the rare codon GGA found in the HBV preS I to the codon preferred by E coli, GGU. The protein was rapidly purified from bacterial lysate by Ni-IDA affinity chromatography. The experimental assays using H-3-labeled substrate demonstrate that the purified HBV preS1-HT can be effectively N-myristoylated by recombinant human protein N-myristoyltransferase (NMT) in vitro. (C) 2002 Elsevier Science (USA). All rights reserved.