Jun,
I don't know if the company still exists, but in 1988 Adams Chemical in
Round Lake, IL sold tyrosine-O-sulfate --- 1g for $35. Very high purity
with a minor contaminant of ring-sulfated tyrosine.
Regards,
Dan L. Crimmins
Washington University School of Medicine
Dept. Pathology/Division of Laboratory Medicine
660 S. Euclid Ave., Box 8118
St. Louis, MO 63110
Phone: 314-454-8514; Fax: 314-454-5208
e-mail: crimmins@labmed.wustl.edu