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Protein hydrolysates (SH, TH) were prepared from eel head by enzymatic treatment using protease. The eel head hydrolysates were used as a natural food preservative by adding to grass carp surimi at the 10% ranging. We compared the effect of protein hydrolysates of eel head with traditional antifreeze on the denatration, gel strength and contents of the salt soluble protein in grass carp surimi during frozen storage at -20°C for 80 days. The addition of eel head hydrolysate markedly decreased the activation rate of the Ca-ATPase. The contents of the salt soluble protein in the grass carp surimi containing eel head hydrolysates were higher than those without eel head hydrolysates (control).Therefore, the gel strength of grass carp surimi media with eel head hydrolysate lower than the others. The result suggests that eel head hydrolysate could suppress the denaturation of grass carp surimi during frozen storage.

Diallyl disulfide (DADS), an oil-soluble organosulfur compound in processed garlic, was more effective in inhibiting the in vitro growth of human tumor cell lines: HCT-15 (colon), A549 (lung), and SK MEL-2 (skin) than isomolar quantities of the water-soluble compound S-allyl cysteine (SAC). Addition of DADS (100 μM) was cytostatic to all three cell lines. The importance of the allyl and the disulfide groups were revealed by the lack of a comparable depression in the growth of HCT-15 cells exposed to its saturated analogue, dipropyl disulfide (DPDS). Treatment with DADS also resulted in a dose-dependent increase in intracellular free calcium in cells. A dose-dependent decrease in the activity of calcium-dependent ATPase enzyme occurred in HCT-15 cells exposed to increasing quantities of DADS. A correlation (r = −0.975) was found between the intracellular free calcium levels and the Ca-ATPase activity in DADS-treated cells. These studies document that DADS, a constituent of garlic oil, is an effective inhibitor of the growth of human neoplastic cells. Alterations in calcium homeostasis are likely involved in the growth inhibition/cytotoxicity caused by DADS.

The properties of the Ca-ATPase prepared from roots of wheat seedlings treated with benzylaminopurine were studied. The affinity of the ATPase towards Ca 2+ , plant or erythrocyte calmodulin increased after the hormonal treatment. It seems that in the membrane calmodulin-bonding sites were induced by benzylaminopurine, contributing to an increased affinity of the ATPase. The lower Ca-content of the hormone-treated plants suggests that in vivo the Ca-ATPase is involved in a Ca-extrusion process.

The sarcoplasmic reticulum Ca-ATPase was subjected to target size analysis by radiation inactivation in various buffer conditions and after solubilization in monomeric form in non-ionic detergent and in SDS. The target size was also determined for Ca-ATPase in bidimensional crystals formed in the presence of decavanadate or lanthanide. The standardization obtained with defined monomers of Ca-ATPase shows that the target size of Ca-ATPase in the functional membrane-bound state may be ascribed to a single peptide chain, possibly with surrounding lipid. Further analysis of the radiation inactivation sizes of various partial reactions of the pump cycle, including phosphorylation and Ca2+ occlusion, indicated much smaller values than the target size pertaining to decomposition of the whole peptide chain. This is consistent with the existence of separate functional domains within a single peptide chain.

Irreversible inactivation of membranous Na,K-ATPase by high-speed centrifugation in dilute aqueous solutions depends markedly on the protonation state of the protein. Pig kidney Na,K-ATPase is irreversibly inactivated at pH 5 but is fully protected at pH 7 and above. Shark rectal gland Na,K-ATPase is irreversibly inactivated at neutral or acidic pH and partially protected at an alkaline pH. The overall Na,K-ATPase activity and the K-dependent pNPPase activity were denatured in parallel. Cryoprotectants such as glycerol or sucrose at concentrations of 25–30% fully protect both enzymes against inactivation. The specific ligands NaCl and KCl protect the Na,K-ATPase activity partially and the pNPPase activity fully at concentrations of 0.2–0.3 M. Electron microscope analysis of the centrifuged Na,K-ATPase membranes revealed that the ultrastructure of the native membranes is preserved upon inactivation. It was also observed that the sarcoplasmic reticulum Ca-ATPase and hog gastric H,K-ATPase are susceptible to inactivation by high-speed centrifugation in a pH-dependent fashion. H,K-ATPase is protected at alkaline pH, whereas Ca-ATPase is protected only in the neutral pH range.