Thyroxine [HSA-Biotin]

Name: Thyroxine [HSA-Biotin]
SKU: DAG470S
Rating: 5 (1 reviews)

Thyroxine, conjugated with biotinylated HSA

COA

SDS

Datasheet

Summary

Target

Thyroxine

Nature

Synthetic

Tag/Conjugate

HSA-Biotin

Molecular Weight

app. 65 kDa

Alternative Names

L-thyroxine; thyroxin; thyroxine

Dilution

Test dependent

Purity

chromatography, dialysis

Format

Liquid

Concentration

1 mg/mL, conjugation ratio is app. 1:10 - 1:40.

Buffer

PBS

Preservative

0.05% sodium azide

Storage

Store at 4°C.

Introduction

The thyroid hormones, triiodothyronine (T3) and its prohormone, thyroxine (T4), are tyrosine-based hormones produced by the thyroid gland that are primarily responsible for regulation of metabolism. Iodine is necessary for the production of T3 and T4. A deficiency of iodine leads to decreased production of T3 and T4, enlarges the thyroid tissue and will cause the disease known as simple goitre. The major form of thyroid hormone in the blood is thyroxine (T4), which has a longer half-life than T3. The ratio of T4 to T3 released into the blood is roughly 20 to 1. T4 is converted to the active T3 (three to four times more potent than T4) within cells by deiodinases (5'-iodinase). These are further processed by decarboxylation and deiodination to produce iodothyronamine (T1a) and thyronamine (T0a). All three isoforms of the deiodinases are selenium-containing enzymes, thus dietary selenium is essential for T3 production.

Antigen Description

Thyroxine, covalently linked to biotinylated human serum albumin

Keywords

drug-HSA-Biotin conjugate, drug-conjugate, thyroxine HSA-Biotin conjugate,thyroxine; T4; T3; thx; thyroxinal; Thyrax; Henning; tetraiodothyronine, triiodothyronine, diiodophenyl-L-alanine; DL-thyroxine, HSA-Biotin, HSA-Biotin - conjugate, T4 - HSA-Biotin, tetraiodothyroxine - HAS

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Background

The thyroid gland weighs about 15 to 20g in adults and has a soft texture. The normal thyroid gland is located in the neck, in front of the trachea, between the cricoid cartilage and the suprasternal notch, with the left and right lateral lobes connected through a thin isthmus. The thickness of the isthmus is about 0.5cm, and the width and height are about 2cm each; the normal lateral leaves are pear-shaped, with the longest thickness and width being about 2.5cm, and the length is about 4cm. Under the microscope, it can be seen that the thyroid gland is composed of dense follicles of varying sizes, interspersed with a rich capillary network. Follicles are ring-shaped structures composed of a single layer of thyroid epithelial cells. The follicles are filled with a clear protein fluid called "colloid" and contain a large amount of thyroglobulin. Under the electron microscope, many microvilli protrude from the surface of follicular cells into the colloid of the follicle cavity. They participate in iodination and exocytosis. The primary stage of hormone secretion, that is, the reabsorption process of colloid occurs here. The thyroid gland also contains parafollicular cells, also known as C cells, which are the source of calcitonin in the body.

Figure 1. The structure of thyroxine.

The thyroid gland can be understood as a follicular cavity made of thyroid epithelial cells. Thyroglobulin is stored in the cavity. Under the action of production workers (thyroid peroxidase, hydrogen peroxide), it reacts with the ingested iodine to form the raw materials monoiodotyrosine and diiodotyrosine are further generated into thyroxine (T4) and triiodothyronine (T3). After the product is generated, it is moved out of the factory by delivery workers (thyroid follicular cells) under the instructions of the superior leader (thyroid stimulating hormone), and is then transported out of the factory by the courier (thyroxine-binding globulin, thyroxine-binding prealbumin, and albumin). It is transported to various places to produce effects. The intake of iodine is an important first step; through food, water enters the gastrointestinal tract and is converted into iodide. The ingested iodide is bound to serum proteins, especially albumin, and unbound iodine is excreted in the urine. This requires the thyroid gland to transport sufficient iodide from the blood circulation against the concentration gradient through the sodium-iodine cotransporter (NIS) on the basolateral membrane of follicular cells. Therefore, the thyroid gland has the function of concentrating iodine, which can make the iodine concentration in the thyroid gland 30 to 40 times higher than the bleeding concentration. Iodide enters the thyroid gland, reaches the follicular cell-colloid interface, and is rapidly oxidized to active iodine under the action of hydrogen peroxide and thyroid peroxidase (TPO), and then reacts with tyrosine residues in thyroglobulin. The bases are combined to form iodotyrosine - monoiodotyrosine (MIT) and diiodotyrosine (DIT). DIT and DIT are coupled to form thyroxine (T4), MIT and DIT are coupled to form triiodothyronine (T3). This process is also catalyzed by TPO. Thiourea drugs, such as propylthiouracil and methimazole, are powerful inhibitors of TPO and can block the synthesis of thyroxine, so they can be used clinically to treat hyperthyroidism. Thyroid hormone is stored in the follicular cavity in colloid form. The thyroid gland is a unique endocrine gland in the body that has a large storage capacity of hormones but a very low conversion rate. The hormone conversion rate is only 1%/d. Under normal circumstances, T4 storage can maintain normal thyroid function in the human body for at least 50 days. Under the stimulation of thyroid stimulating hormone (TSH), thyroid follicular cells engulf colloid through pinocytosis at the cell-colloid interface. The formed phagocytic vesicles fuse with intracellular lysosomes, and Tg (thyroglobulin) is Hydrolyze to release T4, T3, MIT, DIT, peptides and amino acids. T4 and T3 enter the blood circulation, and after MIT and DIT are deiodinated, the iodide produced is stored in the thyroid gland and can be recycled.

Thyroxine is transported by binding to carrier proteins in the serum. The three main transport proteins in the body are thyroxine-binding globulin (TBG) and transthyretin (TTR, also known as thyroxine-binding prealbumin—TBPA) and albumin. Plasma-binding proteins can increase the storage of thyroid hormone in circulating blood and delay the clearance of the hormone. Although the blood concentration of TBG is low (1~2mg/dl), it has a high affinity for thyroid hormones, and about 80% of the bound thyroid hormones are transported by TBG; the blood concentration of albumin is high, but its affinity for thyroid hormones is low. It can combine 5% to 10% of T4 and 30% of T3; TTR combines 10% to 15% of T4. Only about 0.02% of T4 and 0.03% of T3 exist in free form, and free thyroid hormone is truly biologically active. Only free thyroid hormone can determine the metabolic state of the body, participate in negative feedback regulation, and undergo the degradation process.

Alternative Names

L-Thyroxine
3,5,3',5'-Tetraiodothyronine
Levothyroxine
T4 hormone
Thyronorm

References

1. THYROXINE and oxidative phosphorylation. Nutr Rev. 1957, 15(2):61-2.
2. BARKER SB. Thyroxine antagonists. Clin Pharmacol Ther. 1960, 1:797-806.

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References

Comparison of thyroid hormone withdrawal and recombinant human thyroid-stimulating hormone administration for adjuvant therapy in patients with intermediate- to high-risk differentiated thyroid cancer

ANNALS OF NUCLEAR MEDICINE

Authors: Iizuka, Yusuke; Katagiri, Tomohiro; Ogura, Kengo; Inoue, Minoru; Nakamura, Kiyonao; Mizowaki, Takashi

Abstract

Objective To compare the clinical outcome in patients who received adjuvant therapy with radioactive iodine (RAI) using different preparation methods, namely, thyroid hormone withdrawal (THW) and recombinant human thyroid-stimulating hormone (rhTSH), after undergoing thyroidectomy for intermediate- to high-risk differentiated thyroid carcinoma (DTC) according to the American Thyroid Association criteria. Methods Between May 2012 and October 2018, 136 patients who underwent adjuvant therapy with high-dose (3700 MBq) RAI for DTC without any metastatic lesions or macroscopic residual lesions after surgical resection were retrospectively selected. Patients were excluded if distant metastasis was confirmed during adjuvant therapy or if the outcome could not be confirmed; thus, 112 patients were finally evaluated. Patients underwent either a 3-week I restriction with thyroxine withdrawal or a 2-week I restriction with rhTSH administration. The serum thyroglobulin (Tg) concentration was measured, and(131)I scintigraphy (370 MBq) was performed 6-12 months after adjuvant therapy. The definition of the initial achievement of adjuvant therapy was the disappearance of the uptake of(131)I at the thyroid bed and serum Tg concentration < 2.0 ng/mL. The results of the adjuvant therapy between the groups were compared using the Fisher's exact test, and the TSH levels and estimated glomerular filtration rate (eGFR) were compared using the Welch's t test. Results The THW and rhTSH groups included 47 and 65 patients, respectively, and the intermediate- and high-risk groups included 63 and 49 patients, respectively. No patient was assigned to the low-risk group. In the THW and rhTSH groups, the initial RAI adjuvant therapy goal was achieved in 30/47 (63.8%) and 46/65 patients (70.8%), respectively (p = 0.54); mean +/- standard deviation of the TSH levels was 123.8 +/- 46.4 mu IU/mL and 274.5 +/- 97.7 mu IU/mL, respectively (p < 0.01), and eGFR (treatment/pre-treatment) was 0.81 and 0.99, respectively (p < 0.01). In the intermediate- and high-risk groups, the initial RAI adjuvant therapy goal was achieved in 43/63 patients (68.3%) and 33/49 (67.3%), respectively (p = 1.0). Conclusion No significant differences were observed between the preparation methods in the initial achievement of RAI adjuvant therapy. However, patients in the rhTSH group demonstrated higher TSH levels and retained eGFR.

PM Q-probe: A fluorescent binding protein that converts many antibodies to a fluorescent biosensor

BIOSENSORS & BIOELECTRONICS

Authors: Dong, Jinhua; Miyake, Chihiro; Yasuda, Takanobu; Oyama, Hiroyuki; Morita, Izumi; Tsukahara, Tomoya; Takahashi, Masaki; Jeong, Hee-Jin; Kitaguchi, Tetsuya; Kobayashi, Norihiro; Ueda, Hiroshi

Abstract

Quenchbody (Q-body) is a fluorescent biosensor in which a fluorescent dye is tagged near the antigen binding site of an antibody. The fluorescence of the dye is quenched by the tryptophan residues present in the variable region of the antibody, and is recovered when the antigen binds. Q-bodies have been prepared using recombinant DNA technology by introducing one or more tag sequence(s) at either the N-terminal of the Fab or the single chain variable region fragment of the antibody, and labeling the tag with a fluorescent dye. However, preparation of recombinant antibody fragments is time-consuming and the performance of the Q-body is unpredictable. Here we report an antibody-binding quenching probe made from protein M from Mycoplasma genitalium that can transform the IgG antibody into an immunosensor. By using bacterially expressed and purified protein M and labeling the C-terminal cysteine-containing tag, we prepared a TAMRA-labeled PM Q-probe. When the Q probe was incubated with Fab or IgG recognizing the bone Gla protein, the fluorescence of the probe was quenched and subsequently recovered by the adding of antigens in a dose-dependent manner. We also succeeded in detecting several small biomarkers with nanomolar sensitivity, including thyroxine extracted from human serum. The clone found to be suitable for the detection of cortisol was confirmed to work as a recombinant Q body as well, which also worked in 50% human serum. The results suggest that the Q-probe can quickly convert an IgG to a biosensor, which will be useful in rapid diagnosis of small biomarkers.

The many faces of thyroxine

AIMS Neurosci.

Authors: Dratman MB, Martin JV.

Abstract

H?nes et al. have recently shown that in vivo interference with the apparatus of the nuclear receptor-mediated, gene-driven mechanism of triiodothyronine (T3) actions fails to eliminate all actions of T3. However, the investigators conducting that study provided little information regarding the mechanisms that might be responsible for conferring those implied gene-independent effects. Dratman has long ago suggested a system wherein such gene-free mechanisms might operate. Therefore, since news of that discovery was originally published in 1974, it seems appropriate to describe the progress made since then. We propose that thyroxine and triiodothyronine have many different structural properties that may confer a series of different capabilities on their functions. These conform with our proposal that a series of catecholamine analogs and their conversion to iodothyronamines, allows them to perform many of the functions that previously were attributed to nuclear receptors regulating gene expression. The actions of deiodinases and the differential distribution of iodine substituents are among the critical factors that allow catecholamine analogs to change their effects into ones that either activate their targets or block them. They do this by using two different deiodinases to vary the position of an iodide ion on the diphenylether backbones of thyroxine metabolites. A panoply of these structural features imparts major unique functional properties on the behavior of vertebrates in general and possibly on Homo sapiens in particular.