• Applied Biological Chemistry
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• 제19권2호
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• pp.70-74
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• 1976

Thyroid hormone의 생합성반응기작을 알아보기 위하여 방사선 I-131을 쥐에 주사한 후 thyroid gland을 분리하여 분석하였다. Pancreatin viokase를 처리하여 분리한 요드화합물을 여지 크로마토그라피로 분리 동정하고 이를 radioautography로 분석한 결과 I-131은 주사후 바로 쥐의 체내에서 흡수되어 monoiodotyrosine이 되고 이것은 diiodotyrosine으로 전환됨을 관찰하였다. 실험결과는 diiodotyrosine은 thyroxine 생합성에 있어서 중간생성물이나 반면 triiodothyronine은 오히려 분해산물임을 보여 주었다. 또한 환원제인 propylthiouracil을 투여한 쥐에서 iodine의 체내집적현상(Iodine Pump)은 현저히 증가하였으나 유기 요도화합물을 전환되는 것을 저하였다.

• Archives of Pharmacal Research
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• 제24권5호
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• pp.446-454
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• 2001

Peptide fragments, isolated from proteolytic cleavage of thyroglobulin at specific sites, were examined for the iodination of tyrosine residues. The 50 kDa polypeptide, which was prepared from digestion of bovine thyroglobulin and continuous preparative SDS-PAGE, was subjected to reduction with DTT and alkylation with iodoacetic acid to generate S-car-boxymethylated peptide derivative, which was further hydrohysed by endoproteinase-Asp-N. Peptide products were separated by RP-HPLC, and each fraction was analyzed by LC/ESI-MS and MALDI-MS analyses. Based on the specificity of endoproteinase-Asp-N andthe mass spectra data, a peptide fragment turned out to correspond to a peptide, DALCCVKCPEGSYFQ (1438-1452), characterized by the presence of a thioredoxin box (CVKC) and a tyrosine residue. In addition, another peptide fragment (1453-1465) containing a thioredoxin box (CIPC) and a tyrosine residue was also observed. However, any evidence of iodination of the tyrosine residue present in these peptides was not provided. Meanwhile, tyrosine residues in the peptides, DVEEALAGKYLAGRFA (1366-1381) and DYSGLLLAFQVFLL (1290-1303) were found to be iodinated; mono- or diiodinated tyrosine residues, characteristic of a hormogenic site, existed in both peptides. In addition, the tyrosine residue in the peptide (1218-1252), corresponding to a hormonogenic site was also iodinated. Thus, there was a sharp difference of the susceptibility to oxidative iodination between the tyrosine residue in a hormonogenic site and that in a thioredoxin region. From these results, it is suggested that polypeptide region adjacent to tyrosine residues may govern the susceptibility of tyrosine to oxidative iodination.