Opt, codon-optimized; WT, wild-type; AA, animo acids; AP leader, signal peptide of alkaline protease; ASASA, a linker; DDDDK, enterokinase
site; His-tag, 6- histidine tag.
To clarify the reasons for the enterokinase
resistance of [His.sub.6]-FLAG-hIFN[gamma] and [His.sub.6]-FLAG-K88Q fusion proteins expressed in insect cells proteins we performed inducible expression of the same [His.sub.6]-FLAG-tagged fusion genes in E.
Brennan, "Preparation of recombinant thioredoxin fused N-terminal proCNP: analysis of enterokinase
cleavage products reveals new enterokinase
cleavage sites," Protein Expression and Purification, vol.
In order to cleave hPTH from its tag, the desalted fusion protein was digested with enterokinase
enzyme (EK MAX, Invitrogen Co., USA) for 16 hr at room temperature with different enzyme units.
Final analysis of the cassette, using sequencing, showed successful cloning and correct orientation of construct, downstream of enterokinase
(EK) cleavage site (data not shown).
 Nonstandard abbreviations: hK2, human glandular kallikrein 2; PSA, prostate-specific antigen; BPH, benign prostatic hyperplasia; PCa, prostate cancer; rhK2, recombinant hK2; ek, enterokinase
; Xa-rhK2, recombinant prohK2 that can be activated by factor Xa; TWT-rhK2, Turku wild-type recombinant hK2; MAb, monoclonal antibody; thK2, total hK2; RLU, relative light unit(s); and CI, confidence interval.
or enteropeptidase is a heterodimeric serine protease produced by cells in the duodenal wall.
The writer declared that because the proteolytic enzyme exists in the pancreas in an inactive form--trypsinogen--that is activated by enterokinase
secreted by the small intestine, there was no physiologic basis for the duct-ligation experiment.
The pancreatic zymogens were activated with purified enterokinase
(Sigma, 71K7665) using the procedure described by Glazer and Steer (1977) before determination of trypsin and protease.
Trypsin is produced in the exocrine pancreas as two major proenzymes, trypsinogen-1 (cationic) and trypsinogen-2 (anionic), which typically are activated in the duodenum by enterokinase
to trypsin-1 and trypsin-2, respectively.