Factors effecting the thermostability of cysteine proteinases from Carica papaya.
Thermal denaturation of four Carica papaya cysteine proteinases (papain, chymopapain, papaya proteinases 3 and 4) was studied as a function of pH using high-sensitivity differential scanning calorimetry. The ratios of calorimetric enthalpy to Van't Hoff enthalpy suggest that, for all these proteins, denaturation occurs as a non two state process, via an intermediate structure. Differences in the thermal stabilities of 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 similarly used to illustrate the influence of atomic mobility on stability.
Department of Protein Engineering, AFRC Institute of Food Research, Reading Laboratory, England.
I G
IG
Sumner
G W
GW
Harris
M A
MA
Taylor
R W
RW
Pickersgill
A J
AJ
Owen
P W
PW
Goodenough
D002152:Calorimetry, Differential Scanning; D002917:Chymopapain / Q000737:chemistry / Q000378:metabolism; D003546:Cysteine Endopeptidases / Q000737:chemistry* / Q000378:metabolism; D004795:Enzyme Stability; D005638:Fruit / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D010206:Papain / Q000737:chemistry / Q000378:metabolism; D011489:Protein Denaturation; D013696:Temperature; D013816:Thermodynamics
D003546:Cysteine Endopeptidases; D010206:Papain; D002917:Chymopapain