Browsing by Author "Suiko, Masahito"

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A target-specific approach for the identification of tyrosine-sulfated hemostatic proteins
(2009-07-01)
Liu, Tzu-An
;
Yasuda, Shin
;
Williams, Frederick E.
;
Liu, Ming-Yih
;
Suiko, Masahito
A simple methodology for the identification of hemostatic proteins that are subjected to post translational tyrosine sulfation was developed. The procedure involves sequence analysis of members of the three hemostatic pathways using the Sulfinator prediction algorithm, followed by [(35)S]sulfate labeling of cultured HepG2 human hepatoma cells, immunoprecipitation of targeted [(35)S]sulfate-labeled hemostatic proteins, and tyrosine O-[(35)S]sulfate analysis of immunoprecipitated proteins. Three new tyrosine-sulfated hemostatic proteins-protein S. prekallikrein, and plasminogen-were identified. Such a target-specific approach will allow investigation of tyrosine-sulfated proteins of other biochemical/physiological pathways/processes and contribute to a better understanding of the functional role of post-translational tyrosine sulfation. (C) 2009 Elsevier Inc. All rights reserved.
Identification and characterization of two novel cytosolic sulfotransferases, SULT1 ST7 and SULT1 ST8, from zebrafish
(2008-08-29)
Liu, Tzu-An
;
Bhuiyan, Shakhawat
;
Snow, Rhodora
;
Yasuda, Shin
;
Yasuda, Tomoko
Cytosolic sulfotransferases (SULTs) constitute a family of Phase 11 detoxification enzymes that are involved in the protection against potentially harmful xenobiotics as well as the regulation and homeostasis of endogenous compounds. Compared with humans and rodents, the zebrafish serves as an excellent model for studying the role of SULTs in the detoxification of environmental pollutants including environmental estrogens. By searching the expressed sequence tag database, two zebrafish cDNAs encoding putative SULTs were identified. Sequence analysis indicated that these two putative zebrafish SULTs belong to the SULT1 gene family. The recombinant form of these two novel zebrafish SULTs, designated SULT1 ST7 and SULT1 ST8, were expressed using the pGEX-2TK glutathione S-transferase (GST) gene fusion system and purified from transformed BL21 (DE3) cells. Purified GST-fusion protein form of SULT1 ST7 and SULT1 ST8 exhibited strong sulfating activities toward environmental estrogens, particularly hydroxylated polychlorinated biphenyls (PCBs), among various endogenous and xenobiotic compounds tested as substrates. pH-dependence experiments showed that SULT1 ST7 and SULT1 ST8 displayed pH optima at 6.5 and 8.0, respectively. Kinetic parameters of the two enzymes in catalyzing the sulfation of catechin and chlorogenic acid as well as 3-chloro-4-biphenylol were determined. Developmental expression experiments revealed distinct patterns of expression of SULT1 ST7 and SULT1 ST8 during embryonic development and throughout the larval stage onto maturity. (C) 2008 Elsevier B.V. All rights reserved.