Selenium and Iodine Flashcards
3 a.a. in GPx?
Gly-Cys-Glu
what is the 21st amino acid?
selenocysteine (SEC), where Se replaces S
adding microminerals to soil is referred to as:
biofortification
things that prevent absorption of selenium
other metals, phytate
How to make protein containing SEC?
enzyme converts seryl-tRNA to SEC-tRNA during translation
examples of selenoenzymes?
glutathione peroxidase, 5’-deiodinase
how is SEC diff from GLA and OHPro?
added as a.a. during translation, whereas latter are post-translational changes
good food sources of selenium?
fish, brazil nuts, soil levels (esp. affect meat amount)
RDA fro selenium is ___mcg, and EAR is based on:
55; amount needed to maximize synth of GPx
In a region of China, this disease is Se deficiency and viral prob causing fibrosis of heart
Keshan disease
disease involving degeneration of joints, implicating Se deficiency
Kashin-Beck
high Se protects from high ___
arsenic (Bangladesh)
UL for Se is ___mcg from ___ sources
400; all
UL set based on:
hair/nail brittleness (selenosis) in area in China with high Se
UF is set at __ because symptoms are ___
2; irreversible
what does IDD stand for?
iodine deficiency disorders
particular food sources of iodine are referred to as:
goitrogens
active form of thyroid hormones is ____, transport form is ___
T3 (triiodothyronine); T4 (thyroxine)
I binds to ring of ____
tyrosine
where do we store iodide?
in thyroid gland
how is iodide diff from most microminerals?
significant urinary excretion
absorption of I is almost ____%, and in ____
100; stomach and small intestine
why can’t insulin be taken orally?
it is a protein so it would be digested
steps of thyroid hormone synth?
1) I enter thyroid cell by active transport 2) I added to thyroglobin at Tyr (Fe dependent) to make Thg-MIT 3) another I is added to Thg-MIT to make Thg-DIT 4) 2 Thg-DIT make T4, DIT + MIT = T3 5) T3/4 remove from Thg and release to plasma
