Factors effecting the thermostability of cysteine proteinases from Carica papaya

Abstract

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.

Purification of a novel cysteine protease, procerain B, from Calotropis procera with distinct characteristics compared to procerain

“…The total cysteine content of procerain B is found to be nine (measured value 8.86) with one free cysteine residues (measured value 0.89), thus forming four disulphide bridges. Most of the cysteine proteases, including procerain, reported to have total seven cysteine, six cysteine forming three disulfides and one catalytic cysteine [25][26][27][28][29]. However, 11 cysteine [5 disulfide and 1 free] is also reported in plant cysteine protease, heynein [23].…”

Insights into milk-clotting activity of latex peptidases from Calotropis procera and Cryptostegia grandiflora

“…1D). Papain started its denaturation at 45-55°C, according to thermal denaturation studies that used differential scanning calorimetry and spectrophotometric methods (Sumner et al, 1993). Excluding C. papaya peptidases and papain, all samples studied here lost milk-clotting activities after preheating at 75°C for 10 min (Fig.…”

Purification and Characterization of a Novel Protease from the Latex of Pedilanthus tithymaloids

“…The tryptophan and tyrosine content of pedilanthin were higher than other known plant proteases like ervatamin B, ervatamin C, and papain [2,3,26]. One of the striking properties of pedilanthin is the presence of very high sulfhydryl content, from eleven Cys residues.…”

“…The thiol proteases like, asclepain A3 [27], calotropin FII [28] and ervatamin B [3] all have five sulfhydryl group whereas other proteases like ervatamin C [2], papain [26], asclepain B5 [27], calotropin DI, DII, and FI [28], papaya proteinase 3, 4 [26] and actinidin [29] all have seven sulfhydryl group. On the other hand the total cysteine content of chymopapain [26] and ficin [30] are eight, whereas stem bromelain [17] and a cysteine protease from Phaseolus vulgaris [31] have nine. Thus, the presence of five disulfide bonds in pedilanthin is relatively unique and may be the reason for its high temperature and pH optima.…”