Hormonogenic donor Tyr2522 of bovine thyroglobulin. Insight into preferential T3 formation at thyroglobulin carboxyl terminus at low iodination level
- Dipartimento di Medicina e Scienze della Salute, Università del Molise, Via De Sanctis, snc, Campobasso 86100 (Italy)
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università di Napoli Federico II, Via S. Pansini, 5, Napoli 80131 (Italy)
- Centro di Spettrometria di Massa Proteomica e Biomolecolare, ISA-CNR, Via Roma 52 a, Avellino 83100 (Italy)
- Dipartimento di Agraria, Università di Napoli “Federico II”, Parco Gussone, Portici (Napoli) 80055 (Italy)
Highlights: • A carboxy-terminal fragment (residues 2515–2750) was isolated from a low-iodine bTg. • Post-translational status of 8 tyrosines in bTg region 2515–2750 was assessed by MS. • Tyr2522 of bovine Tg is an interspecifically conserved hormonogenic donor site. • Propensities of Tyr residues to mono or diiodination optimize T3 yield from Tyr2748. - Abstract: A tryptic fragment (b5{sub TR,NR}), encompassing residues 2515–2750, was isolated from a low-iodine (0.26% by mass) bovine thyroglobulin, by limited proteolysis with trypsin and preparative, continuous-elution SDS–PAGE. The fragment was digested with Asp-N endoproteinase and analyzed by reverse-phase HPLC electrospray ionization quadrupole time-of-flight mass spectrometry, revealing the formation of: 3-monoiodotyrosine and dehydroalanine from Tyr2522; 3-monoiodotyrosine from Tyr2555 and Tyr2569; 3-monoiodotyrosine and 3,5-diiodotyrosine from Tyr2748. The data presented document, by direct mass spectrometric identifications, efficient iodophenoxyl ring transfer from monoiodinated hormonogenic donor Tyr2522 and efficient mono- and diiodination of hormonogenic acceptor Tyr2748, under conditions which permitted only limited iodination of Tyr2555 and Tyr2569, in low-iodine bovine thyroglobulin. The present study thereby provides: (1) a rationale for the preferential synthesis of T3 at the carboxy-terminal end of thyroglobulin, at low iodination level; (2) confirmation for the presence of an interspecifically conserved hormonogenic donor site in the carboxy-terminal domain of thyroglobulin; (3) solution for a previous uncertainty, concerning the precise location of such donor site in bovine thyroglobulin.
- OSTI ID:
- 22416639
- Journal Information:
- Biochemical and Biophysical Research Communications, Vol. 450, Issue 1; Other Information: Copyright (c) 2014 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0006-291X
- Country of Publication:
- United States
- Language:
- English
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