Calorimetric studies on dry pectinlyase preparations: impact of glass transition on inactivation kinetics.
The glass transition temperature (T(g)) of a dry ultrafiltrated pectinlyase (PL) preparation decreased from 56 to 24 degrees C when water content increased to 20%. The thermal transition temperature (T(p)) for protein denaturation decreased greatly up to 40% moisture; above 40% no further changes in T(p) were observed. In the glassy state, a lag period of approximately 7 days with no PL activity loss was observed; after that, PL activity was lost. Above T(g), the rates of PL inactivation greatly increased. In the glassy state E(a) was 16.6 kJ/mol. When the system was in a higher mobility state (rubbery), E(a) increased to 66.5 kJ/mol.
Taragano
V M
VM
Departamento de Industrias, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, 1428 Buenos Aires, Argentina.
Pilosof
A M
AM
D002152:Calorimetry, Differential Scanning / Q000379:methods; D004789:Enzyme Activation; D004795:Enzyme Stability; D005898:Glass; D007700:Kinetics; D011133:Polysaccharide-Lyases / Q000737:chemistry* / Q000378:metabolism; D014462:Ultrafiltration; D014867:Water
D014867:Water; D011133:Polysaccharide-Lyases; C027349:pectin lyase