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The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Administrative data

Link to relevant study record(s)

Description of key information

Waiving: study scientifically unjustified.

Key value for chemical safety assessment

Additional information

In the Maeda et al (1996 [1]) literature study the melting temperature for lysozyme was investigated using the differential scanning calorimeter (DSC) with and without additive. In the absence of additive, the melting temperature of lysozyme was reported 73.8°C.

Enzymes are polymers of 20 different naturally occurring amino acids in various length and order. The amino acids sequence determines the structure of the enzyme since at biological conditions the structure of this polymer is defined by the energy minimum fold. The enzyme fold and structure is held together primarily by hydrogen bonds, hydrophobic interactions, ion bonds and van der Waals forces between the different amino acids and cofactors. When heating the enzymes above the biological conditions, typically 80°C and higher, the attracting forces within the enzymes are broken, the fold is disrupted and the enzyme denatures. Once denatured, the enzymes lose their activity and typically coagulate. Thus a classical melting point is not relevant for enzymes.

Reference

[1] Yoshitake Maeda, Hidenori Yamada, Tadashi Ueda and Taiji Imoto. Effect of additives on the renaturation of reduced lysozyme in the presence of 4 M urea. Protein Engineering vol.9 no.5 pp.461^165, 1996