The physiological mechanism of maintaining the green colour of pak choy leaves (Brassicarapa var chinensis) with heat-shock treatment was studied. Chlorophyll in the outerleaves of pak choy degraded rapidly during sto...The physiological mechanism of maintaining the green colour of pak choy leaves (Brassicarapa var chinensis) with heat-shock treatment was studied. Chlorophyll in the outerleaves of pak choy degraded rapidly during storage at ambient temperature (20±2℃), aslight yellow appeared. Heat-shock treatment (46-50℃) had a mild effect on maintainingthe green colour of outer leaves. Normal chlorophyll degradation was associated with abinding of chlorophyll with chlorophyll-binding-protein preceding chlorophyll breakdown.Heat-shock treatment was found to reduce the binding-capacity between chlorophyll-binding-protein and chlorophyll. In the chlorophyll degradation pathway, pheide dioxygenasewas synthesized during leaf senescence which was considered to be a key enzyme inchlorophyll degradation. Activity of this enzyme was reduced following heat-shocktreatment, which might explain the observed reduction in chlorophyll breakdown. Twogroups of heat-shock proteins were detected in treated leaves, the first group containingproteins from 54KDa to 74Kda, and the second group contained proteins from 15KDa to29KDa. Heat-shock treatment was also found to retard the decline of glucose and fructose(the main energy substrates) of outer leaves.展开更多
Both α crystallin from bovine eye lens and Hsp16.3 from Mycobacterium tuberculosis are members of the small heat shock protein family. They were preincubated at 100 ℃ for 15 min and then cooled on ice immedi...Both α crystallin from bovine eye lens and Hsp16.3 from Mycobacterium tuberculosis are members of the small heat shock protein family. They were preincubated at 100 ℃ for 15 min and then cooled on ice immediately. The chaperone like activities of preheated proteins were measured at 37 ℃ using DTT treated insulin B chains as substrates. Both preheated proteins exhibited greatly enhanced chaperone like activities, accompanied with almost unchanged secondary structures and surface hydrophobicity but with a minor change in tertiary structures. The dramatically enhanced chaperone like activities of preheated α crystallin and Hsp16.3 may have resulted from the irreversible change in the tertiary structure as detected by near UV CD spectra.展开更多
文摘The physiological mechanism of maintaining the green colour of pak choy leaves (Brassicarapa var chinensis) with heat-shock treatment was studied. Chlorophyll in the outerleaves of pak choy degraded rapidly during storage at ambient temperature (20±2℃), aslight yellow appeared. Heat-shock treatment (46-50℃) had a mild effect on maintainingthe green colour of outer leaves. Normal chlorophyll degradation was associated with abinding of chlorophyll with chlorophyll-binding-protein preceding chlorophyll breakdown.Heat-shock treatment was found to reduce the binding-capacity between chlorophyll-binding-protein and chlorophyll. In the chlorophyll degradation pathway, pheide dioxygenasewas synthesized during leaf senescence which was considered to be a key enzyme inchlorophyll degradation. Activity of this enzyme was reduced following heat-shocktreatment, which might explain the observed reduction in chlorophyll breakdown. Twogroups of heat-shock proteins were detected in treated leaves, the first group containingproteins from 54KDa to 74Kda, and the second group contained proteins from 15KDa to29KDa. Heat-shock treatment was also found to retard the decline of glucose and fructose(the main energy substrates) of outer leaves.
基金Supported by the National Natural Science Foundation of China ( No.3 970 0 0 2 5 ) and the National Science Foundation for Outstanding Young Scientists in China ( No.3 972 5 0 0 8)
文摘Both α crystallin from bovine eye lens and Hsp16.3 from Mycobacterium tuberculosis are members of the small heat shock protein family. They were preincubated at 100 ℃ for 15 min and then cooled on ice immediately. The chaperone like activities of preheated proteins were measured at 37 ℃ using DTT treated insulin B chains as substrates. Both preheated proteins exhibited greatly enhanced chaperone like activities, accompanied with almost unchanged secondary structures and surface hydrophobicity but with a minor change in tertiary structures. The dramatically enhanced chaperone like activities of preheated α crystallin and Hsp16.3 may have resulted from the irreversible change in the tertiary structure as detected by near UV CD spectra.
