Structural Characterization of Thymidine Phosphorylase Purified from Human Placenta

• Published in: Biochemical and biophysical research communications 1995-07, Vol.212 (3), p.1040-1045
• Main Authors: Miyadera, K., Dohmae, N., Takio, K., Sumizawa, T., Haraguchi, M., Furukawa, T., Yamada, Y., Akiyama, S.I.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Blood Platelets - metabolism; Female; Humans; Molecular Sequence Data; Placenta - enzymology; Pregnancy; Protein Biosynthesis; Protein Processing, Post-Translational; Sequence Homology, Amino Acid; Thymidine Phosphorylase - genetics; Thymidine Phosphorylase - isolation & purification
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1006/bbrc.1995.2074

Human thymidine phosphorylase (dThdPase) is thought to be identical to an angiogenesis factor, platelet-derived endothelial cell growth factor (PD-ECGF). However, the whole amino acid sequence of dThdPase is still unknown. N-terminal amino acid sequencing of dThdPase isolated from human placenta gave the sequence Ac-AALMTPGTGAPPAPG. Comparison with the sequence predicted from the PD-ECGF cDNA reveals that residues 216 of dThdPase are identical to that of PD-ECGF. If dThdPase and PD-ECGF are derived from the same gene, the primary translational product of dThdPase would be processed one amino acid from the translation-initiating methionine residue and Ala-2 acetylated. Since placental and platelet PD-ECGF is reported to be processed at Thr-6 and Ala-11, respectively, and the N-terminal end is not blocked, further study is needed to clarify the reason for this discrepancy and whether the difference in N-terminal sequence affects the physiological function of these molecules.