Ginger rhizome as a potential source of milk coagulating cysteine protease.

A milk coagulating protease was purified ∼10.2-fold to apparent homogeneity from ginger rhizomes in 34.9% recovery using ammonium sulfate fractionation, together with ion exchange and size exclusion chromatographic techniques. The molecular mass of the purified protease was estimated to be ∼36kDa by SDS-PAGE, and exhibited a pI of 4.3. It is a glycoprotein with 3% carbohydrate content. The purified enzyme showed maximum activity at pH 5.5 and at a temperature of ∼60°C. Its protease activity was strongly inhibited by iodoacetamide, E-64, PCMB, Hg(2+) and Cu(2+). Inhibition studies and N-terminal sequence classified the enzyme as a member of the cysteine proteases. The cleavage capability of the isolated enzyme was higher for α(s)-casein followed by ß- and κ-casein. The purified enzyme differed in molecular mass, pI, carbohydrate content, and N-terminal sequence from previously reported ginger proteases. These results indicate that the purified protease may have potential application as a rennet substitute in the dairy industry.

STUDY ON THE ANTIOXIDATIVE ACTIVITY AND EFFECTS ON EXPERIMENTAL HYPERLIPIDEMIA OF NATTO EXTRACT / 营养学报

Objective: To study the antioxidation and effects of water soluble extract from Natto on hyperlipidemia. Methods: The model of experimental hyperlipidemia was induced by high cholesterol diet. 18 rabbits were divided into 3 groups : model group, natto extract group and control group. Results: The natto extract could reduce the blood total cholesterol (TC), triglyceride (TG), low density lipoprotein cholesterol (LDL-C), malon-dialdehyde (MDA), atherogenic index (AI) of experimental rabbits 39.88% , 44.54% , 48.84%, 48.25% and 70.20%, respectively, and increase high density lipoprotein cholesterol (HDL-C), superoxide dismutase(SOD) 75.81% and 38.32%, respectively. Natto extract could prevent effectively the fatty degeneration of liver cells observed by pathological sections. Conclution: Natto extract can efficiently prevent the formation of experimental hyperlipidemia.