1. Liothyronine
Liothyronine (T3) is a normal component of human milk. If replacement doses of liothyronine are required by the mother, it is not necessarily a reason to discontinue breastfeeding. However, because no information is available on the use of exogenous liothyronine during breastfeeding, an alternate drug may be preferred. The American Thyroid Association recommends that subclinical and overt hypothyroidism should be treated with levothyroxine in lactating women seeking to breastfeed.[1] Liothyronine dosage requirement may be increased in the postpartum period compared to prepregnancy requirements patients with Hashimoto's thyroiditis.[2]
2. Affinity chromatography of porcine pepsin on different types of immobilized 3,5-diiodo-L-tyrosine
M Tichá, Z Kucerová, H Arnostová, T Trnka, I Tislerová J Chromatogr A . 2001 Mar 16;911(2):211-6. doi: 10.1016/s0021-9673(00)01255-3.
The preparation of affinity sorbents containing immobilized iodinated derivatives of L-tyrosine for the affinity chromatography of porcine pepsin is described. The ligand was coupled either to Sepharose 4B or bead cellulose after the divinylsulfone activation or to Sepharose 4B after the activation with 2,4,6-trichloro-1,3,5-triazine. The highest capacity for porcine pepsin was found in the case of 3,5-diiodo-L-tyrosine coupled to divinylsulfone-activated Sepharose.
3. Horseradish peroxidase. XLII. Oxidations of L-tyrosine and 3,5-diiodo-L-tyrosine by compound II
I M Ralston, H B Dunford Can J Biochem . 1980 Nov;58(11):1270-6. doi: 10.1139/o80-170.
The oxidations of both L-tyrosine and 3,5-diiodo-L-tyrosine by compound II of horseradish peroxidase were studied over the pH range of approximately 5 to 10 at 25 degrees C and at a constant ionic strength of 0.11. The rate versus pH profile for the tyrosine - compound II reaction illustrates the influences of at least two acid group ionizations. An enzyme dissociation (pKa approximately 6.2) has a small effect on the reaction rate; whereas, a second pKa of 9.2, which may be attributed to either the enzyme or substrate, has a greater influence on the rate. The oxidation of tyrosine by compound II is fastest at pH 7.6. In the case of the diiodotyrosine - compound II reaction, three acid dissociations are necessary to describe the plot of log (kaap) versus pH. These include two enzyme pKa values of 3.6 and 8.6, and one substrate pKa of 6.6. The rate optimum for the reaction occurs at pH 5.2 and deprotonation of the phenolic group of diiodotyrosine results in a dramatic decrease in kapp. Diiodotyrosine is required in only a 0.5 M equivalent for the conversion of horseradish peroxidase compound I to compound II. The diiodotyrosine pKa values were estimated as 6.4 and 9.4 for the phenolic and amino groups, respectively.
