An antiproliferative efficacy of BSA-MTX conjugates against MTX-sensitive CNS-1 cells.

<p>An antiproliferative efficacy of BSA-MTX conjugates against MTX-sensitive CNS-1 cells.</p

Schematic presentation of the proposed mechanisms involved in the chemical hydrolysis of methotrexate-amino derivatives covalently linked to carboxylate moieties of macromolecules (A) at acidic (B) and neutral (C) pH values.

<p>Schematic presentation of the proposed mechanisms involved in the chemical hydrolysis of methotrexate-amino derivatives covalently linked to carboxylate moieties of macromolecules (A) at acidic (B) and neutral (C) pH values.</p

Engineering a cysteine-specific MTX-containing reagent- Rates of hydrolysis following its conjugation to PEG₂₀-SH or to HSA at acidic pH.

<p>PEG₂₀-S-MAL-(CH₂)₂-CONH(CH₂)₆-NHCO-MTX and HSA-S-MAL-(CH₂)₂-CONH(CH₂)₆-NHCO-MTX were dialyzed against 1L of 1mM HCl and the decrease in the absorbance at 305nm in the dialysis tube was recorded applying the protocol as described in the legend for <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0158352#pone.0158352.g001" target="_blank">Fig 1</a>. Data are presented as mean±STDEV (n = 4).</p

Decrease in the absorbance of PEG₄₀-CONH-(CH₂)₅-CONH-(CH₂)₆-NHCO-MTX with time during dialysis against 1mM HCl.

<p>PEG₄₀-CONH-(CH₂)₅-CONH-(CH₂)₆-NHCO-MTX and PEG₄₀-CONH-(CH₂)₆-NHCO-MTX (0.2 μmole/ml of each) were dialyzed against one liter of 1mM HCl (pH 3.0). At the indicated time points, 30 μl aliquots were withdrawn from the dialysis tube, diluted 20 folds and their absorbance at 305 nm was monitored. Data are presented as mean±STDEV (n = 3).</p