Open Access Received: 05 March 2025   |   Accepted: 08 July 2025   |   Published: 08 July 2025

POLYAMPHOLYTIC PROPERTIES OF PROTEIN FROM BOMBYX MORI SILKWORM PUPAE

Avazova O.B., Milusheva R.Yu., Rashidova S.Sh.

Institute of Polymer Chemistry and Physics Uzbekistan Academy of Sciences, 100128, Tashkent, Uzbekistan

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Abstract. The polyampholytic properties of Bombyx mori silk protein were studied using conductometry, viscometry, and potentiometry methods. During the titration of a 1% protein solution by the conductometry method, an increase in electrical conductivity (Gsm) was observed in a linear manner within the NaOH solution volume range of V = 4.4 – 5.4 ml, which was determined to correspond to the titration of up to 4.7% of the amino groups. When the viscosity of a 2% aqueous protein solution was examined using the viscometry method, an anomalous change characteristic of polyampholytic properties was observed upon dilution with water. However, when added with a 2% NaCl solution, this anomaly was eliminated, and the characteristic viscosity was determined to be [η] = 0.13 dl/g. Conformational changes in the protein chain were analyzed by potentiometric titration of 1% Bombyx mori alkaline hydrolysate (pH 11.9) with 38% acetic acid. As the pH of the protein hydrolysate transitioned from alkaline to acidic through neutral conditions (pH 11.9–2.7), anomalous changes in the relative viscosity (ηrel) of the solution were observed. This was attributed to conformational changes in the protein, which resulted from the ionization of its basic (NH⁺) and acidic (COO⁻) groups, characteristic of polyampholytic properties. The analysis revealed that Bombyx mori protein comprises 18 amino acids, accounting for 28% of the dry weight (280.546 mg/g), composed of: 10 nonpolar amino acids (113.4 mg), 3 uncharged polar amino acids (82.6 mg), 3 basic amino acids (15.8 mg), 2 acidic amino acids (68.7 mg).

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Key words. bombyx mori protein solution, isoelectric point, polyampholyte macromolecule, hydrodynamic studies


DOI: http://uzpolymerjournal.com/articles/article.php?id=250202

*Corresponding author: Avazova O.B., Institute of Polymer Chemistry and Physics Uzbekistan Academy of Sciences, 100128, Tashkent, Uzbekistan.

Citation: Avazova O.B., Milusheva R.Yu., Rashidova S.Sh., POLYAMPHOLYTIC PROPERTIES OF PROTEIN FROM BOMBYX MORI SILKWORM PUPAE. Uzbekistan Journal of Polymers, Vol. 4(2) 2025: pp.15-22. DOI: http://uzpolymerjournal.com/articles/article.php?id=250202

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