Search

Dregea sinensis (D. sinensis) stems have traditionally been used as milk coagulant in Dali of Yunnan Province, China. In this study, proteomics was used to investigate the bio-functions of D. sinensis stem proteins, leading to the purification and identification of the milk-clotting enzyme. A total of 205 proteins mainly involved in the catalytic and metabolic processes were identified, of which 28 proteins exhibited hydrolase activity. Among the 28 proteins, we focused on two enzymes (M9QMC9 and B7VF65). Based on proteomics, a cysteine protease (M9QMC9) with a molecular weight of 25.8 kDa and milk-clotting activity was purified from D. sinensis stems using double ammonium sulfate precipitation and was confirmed using liquid chromatography-mass spectrometry (LC-MS/MS). The milk-clotting temperature using the purified enzyme was around 80 °C (specific activity at 314.38 U/mg), and it was found to be stable in the pH range of 6-9 in NaCl concentration of <0.8 mol/L. These findings indicated that the enzyme isolated from D. sinensis stems has potential in the dairy and food sectors, especially in the cheese-making industry., (Copyright © 2021. Published by Elsevier Ltd.)

Cathepsin L (CatL) is a potent collagenase involved in atherosclerotic vascular remodeling and dysfunction in animals and humans. This study investigated the hypothesis that plasma CatL is associated with the prevalence of coronary artery disease (CAD). Between February May 2011 and January 2013, 206 consecutive subjects were enrolled from among patients who underwent coronary angiography and percutaneous coronary intervention treatment. Age-matched subjects (n = 215) served as controls. Plasma CatL and high-sensitive C-reactive protein (hs-CRP) and high-density lipoprotein cholesterol were measured. The patients with CAD had significantly higher plasma CatL levels compared to the controls (1.4 ± 0.4 versus 0.4 ± 0.2 ng/mL, P < 0.001), and the patients with acute coronary syndrome had significantly higher plasma CatL levels compared to those with stable angina pectoris (1.7 ± 0.7 versus 0.8 ± 0.4 ng/mL, P < 0.01). Linear regression analysis showed that overall, the plasma CatL levels were inversely correlated with the high-density lipoprotein levels (r = -0.32, P < 0.01) and positively with hs-CRP levels (r = 0.35, P < 0.01). Multiple logistic regression analyses shows that cathepsin L levels were independent predictors of CAD (add ratio, 1.8; 95% CI, 1.2 to 2.1; P < 0.01). These data demonstrated that increased levels of plasma CatL are closely associated with the presence of CAD and that circulating CatL serves as a useful biomarker for CAD.