Characteristics of the Inhibition of Potato (Solanum tuberosum) Invertase by an Endogenous Proteinaceous Inhibitor in Potatoes

Abstract

Effect of several parameters on inhibition of potato (Solanum tuberosum) invertase by its endogenous proteinaceous inhibitor was determined using homogeneous preparations of both proteins. The inhibitor and invertase formed an inactive complex with an observed association rate constant at pH 4.70 and 37°C of 8.82 x 102 per molar per second and a dissociation rate constant of 3.3 x 10-3 per minute. The inhibitor appeared to bind to invertase in more than one step. Initial interaction (measured by loss of invertase activity) was rapid, relatively weak, readily reversible (K, of 2 x 10-6 molar) and noncompetitive with substrate at pH 4.70. Initial interaction was probably followed by isomerization to a tighter (K, of 6.23 x 10-i molar) complex, which dissociated slowly with a half-time of 3.5 hour. Interaction between enzyme and inhibitor appeared to be of ionic character and essentially pH independent between pH 3.5 and 7.4. Schwimmer et al. (19) first reported evidence for an endogenous proteinaceous inhibitor ofinvertase in potatoes. Pressey (15,16) purified the inhibitor to homogeneity and partially characterized it. Invertase inhibitors have been found also in red beet, sugar beet, and sweet potato (1 1, 17) and in maize endosperm (9).Invertase inhibitors have been implicated in the regulation of invertase activity in several plant tissues. In potato tubers, the inhibitor may play a role in the increase of invertase activity resulting from cold treatment, wounding, or transferring of callus into liquid medium. Some aspects of the interaction between potato invertase and invertase inhibitor using crude preparations of both proteins have been reported by Ewing and McAdoo (6)

Purification and characterization of a soluble β‐fructofuranosidase from Daucus carota

“…( Faye et al, 1981), wheat (Krishnan et al, 1985), ricinus (Prado et al, 1985), maize (Doehlert and Felker, 1987), carnation (Woodson and Wang, 1987), artichoke (Goupil et d., 1988), barley (Karuppiah el al., 1989), stinging nettle (Fahrendorf and Beck, 1990), potato (Bracho and Whitaker, 1990), cherry (Krishnan and Pueppke, 1990), carrot (Lauriere et al, 1988;Stommel and Simon, 1990), tomato (Yelle et al, 1991) and peach (Moriguchi et al, 1991). All soluble /?-fructofuranosidases characterized have a K,,, for sucrose in the millimolar range at a pH optimum between 4.5 and 5.5.…”

Changes in sugar content and activity of vacuolar acid invertase during low-temperature storage of potato tubers from six Japanese cultivars

“…Crude extracts of potato tubers usually contain a small protein that has an inhibitory effect on soluble acid invertase activity (Pressey 1967;Ewing and McAdoo 1971;Bracho and Whitaker 1990). However, Ross and Davies (1992) have pointed out that techniques such as rapid vortexing and foaming of extracts, which were developed to destroy the inhibitor, are severe and that a possible loss of invertase could occur.…”

Allele diversity for the apoplastic invertase inhibitor gene from potato

“…Pressey (1966Pressey ( , 1967 puriWed the inhibitor to homogeneity and partially characterised it as a protein with a molecular weight of about 17 kDa. Such invertase inhibitors have been reported from a number of plants (Pressey 1967(Pressey , 1968(Pressey , 1994Krausgrill et al 1998;Reca et al 2008), with molecular weights ranging from 15 to 23 kDa (Pressey 1967;Bracho and Whitaker 1990;Krausgrill et al 1998). The Wrst N-terminal sequences for putative invertase inhibitor proteins from tomato fruit and tobacco cell suspension cultures were reported by Pressey (1994) and Weil et al (1994), respectively.…”