Ig. Sumner et al., FACTORS EFFECTING THE THERMOSTABILITY OF CYSTEINE PROTEINASES FROM CARICA-PAPAYA, European journal of biochemistry, 214(1), 1993, pp. 129-134
Thermal denaturation of four Carica papaya cysteine proteinases (papai
n, chymopapain, papaya proteinases 3 and 4) was studied as a function
of pH using high-sensitivity differential scanning calorimetry. The ra
tios of calorimetric enthalpy to Van't Hoff enthalpy suggest that, for
all these proteins, denaturation occurs as a non two state process, v
ia an intermediate structure. Differences in the thermal stabilities o
f the proteinases; chymopapain > papaya proteinase 3 > papain > papaya
proteinase 4, were correlated to their amino acid sequence to explain
the observations in terms of mobility and specific residue mutation.
Three-dimensional structures of papain and papaya proteinase 3 were si
milarly used to illustrate the influence of atomic mobility on stabili
ty.