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Research articles

ScienceAsia 47 (2021): 449-456 |doi: 10.2306/scienceasia1513-1874.2021.057

The influence of Zn2+-binding motif sequence on the catalytic activity of transthyretin towards amyloid beta

Waralee Krainara, Ladda Leelawatwattana, Porntip Prapunpoj*

ABSTRACT:     The proteolysis property of transthyretin (TTR) was believed to be important for physiological processes and have therapeutic potential. In the present study, we interchanged the corresponding sequences of Zn2+ binding motif between human and Crocodylus porosus TTRs. The kinetic parameters of the proteolytic activity towards amyloid beta 1-42 (A?1-42) of the mutated TTRs were determined by using a sensitive fluorescence-based method, and compared with the wild types. The results showed that C. porosus TTR with Zn2+-binding motif sequence of human TTR (hu-motif/crocTTR) has apparent Km (Kapp m ) of 118?13 ?M which was significantly higher than those for human TTR (53.6?1.5 ?M), C. porosus TTR (crocTTR) (30.2?4.0 ?M), and human TTR with Zn2+-binding motif sequence of C. porosus TTR (croc-motif/huTTR) (53.4?0.87 ?M). In addition, the catalytic efficiency (Vmax/Kapp m ) of croc-motif/huTTR (1.16?0.0066 RFU min?1?M?1) was significantly higher than human TTR (0.639?0.0085 RFU min?1?M?1) but similar to those of crocTTR (1.11?0.082 M?1min?1) and hu-motif/crocTTR (0.894?0.031 RFU min?1?M?1). The obtained results provided insight of the influence of the Zn2+-binding motif sequence and the evolutionary change structure on the proteolytic activity towards A? of TTR and useful information for designing a therapeutic TTR.

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a Department of Biochemistry, Division of Health and Applied Sciences, Faculty of Science, Prince of Songkla University, Songkhla 90110 Thailand

* Corresponding author, E-mail: porntip.p@psu.ac.th

Received 10 Sep 2020, Accepted 1 May 2021