Linked Life Data

10719389

Source:http://linkedlifedata.com/resource/pubmed/id/10719389

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
2000-8-24
pubmed:abstractText
Normal in vitro thyroid peroxidase (TPO) iodide oxidation activity was completely inhibited by a hydrolyzed TPO preparation (0.15 mg/ml) or hydrolyzed bovine serum albumin (BSA, 0.2 mg/ml). A pancreatic hydrolysate of casein (trypticase peptone, 0.1 mg/ml) and some amino acids (cysteine, tryptophan and methionine, 50 microM each) also inhibited the TPO iodide oxidation reaction completely, whereas casamino acids (0.1 mg/ml), and tyrosine, phenylalanine and histidine (50 microM each) inhibited the TPO reaction by 54% or less. A pancreatic digest of gelatin (0.1 mg/ml) or any other amino acid (50 microM) tested did not significantly decrease TPO activity. The amino acids that impair iodide oxidation also inhibit the TPO albumin iodination activity. The inhibitory amino acids contain side chains with either sulfur atoms (cysteine and methionine) or aromatic rings (tyrosine, tryptophan, histidine and phenylalanine). Among the amino acids tested, only cysteine affected the TPO guaiacol oxidation reaction, producing a transient inhibition at 25 or 50 microM. The iodide oxidation inhibitory activity of cysteine, methionine and tryptophan was reversed by increasing iodide concentrations from 12 to 18 mM, while no such effect was observed when the cofactor (H2O2) concentration was increased. The inhibitory substances might interfere with the enzyme activity by competing with its normal substrates for their binding sites, binding to the free substrates or reducing their oxidized form.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
0100-879X
pubmed:author
pubmed:issnType
Print
pubmed:volume
33
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
355-61
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2000
pubmed:articleTitle
Thyroid peroxidase activity is inhibited by amino acids.
pubmed:affiliation
Laboratório de Fisiologia Endócrina, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brasil.
pubmed:publicationType
Journal Article, In Vitro, Research Support, Non-U.S. Gov't