Casein hydrolysis by Bifidobacterium longum KACC91563 and antioxidant activities of peptides derived therefrom.

Milk protein is a well-known precursor protein for the generation of bioactive peptides using lactic acid bacteria. This study investigated the antioxidant activity of bovine casein hydrolysate after fermentation with Bifidobacterium longum KACC91563 using the 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assay and total phenolic content (TPC). The antioxidant activities of the 24-h and 48-h hydrolysates were higher than that of the 4-h hydrolysate (2,045.5 and 1,629.3 µM gallic acid equivalents, respectively, vs. 40.3 µM) in the ABTS assay. In contrast, TPC values showed activities of 43.2 and 52.4 µM gallic acid equivalents for the 4-h and 24-h hydrolysates, respectively. Three fractions (≥10 kDa, ≥3 but <10 kDa, and <3 kDa) were separated from the 24-h hydrolysate by ultrafiltration. Among these fractions, the <3 kDa fraction exhibited the highest antioxidant activity (936.7 µM) compared with the other fractions (42.1 and 34.2 µM for >10 kDa and 3-10 kDa fractions, respectively). Through liquid chromatography-electrospray ionization-tandem mass spectrometry analysis, 2 peptides, VLSLSQSKVLPVPQK and VLSLSQSKVLPVPQKAVPYPQRDMPIQA, containing the fragment VLPVPQ that has antioxidant properties, were identified in the <3kDa fraction after 24h of hydrolysis. The present study demonstrates the possibility of antioxidant peptide production from bovine casein using Bifidobacterium longum.

Separation of ovotransferrin from chicken egg white without using organic solvents.

Ovotransferrin is one of the major egg white proteins that have antimicrobial activity as well as iron binding capability. The objective of this study was to develop a simple and easy method to separate ovotransferrin without using organic solvents. Egg white was separated from yolk, added in a 1:1 ratio to distilled water (DW), and then homogenized. The ovomucin in the diluted egg white was removed by centrifugation, adjusting the pH to 4.5 to 5.0. The resulting supernatant was added to different ratios of ammonium sulfate and citric acid, and then centrifuged after holding overnight at 4°C. The precipitant, which contains ovotransferrin, was dissolved in DW, and ovotransferrin was precipitated using different ratios of ammonium sulfate and citric acid. The precipitant collected after centrifugation was dissolved with DW and subjected to ultrafiltration to remove salts and concentrate the solution. The purity of the ovotransferrin was determined using SDS-PAGE, the protein identified using Western blot, and the estimated yield calculated by weighing the ovotransferrin after freeze drying. Over 85% purity and over 83% yield were obtained from the combinations of 5.0% (wt/vol) ammonium sulfate and 2.5% (wt/vol) citric acid followed by 2.0% (wt/vol) ammonium sulfate and 1.5% (wt/vol) citric acid. Activity of the ovotransferrin showed similar activity with previously separated ovotransferrin. However, this method is simpler and more cost effective than the previous method. The isolated ovotransferrin can be used as is or after modifications for various applications such as antimicrobial treatments, anticancer treatments, and iron-supplementing agents for humans.

Determination of molecular weights of caprine milk proteins by matrix-assisted laser desorption/ionization mass spectrometry.

Molecular weights (MW) of major proteins in milk of 3 Korean dairy goat breeds were determined by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, after treatment of milk samples with the reduction buffer used in capillary electrophoresis. The MW of caprine milk proteins were compared with those of Holstein milk counterparts using commercial bovine milk protein standards. The MW of α-lactalbumin, ß-lactoglobulin, and α- and ß-casein standards were 14,197±3.4, 18,326±26.3, 23,591±13.0, and 23,967±12.8 m/z, respectively, whereas those of Holstein milk treated with the reduction buffer were 14,199±8.3, 18,397±25.9, 23,614±64.8, and 23,984±75.6 m/z, respectively. The respective MW of α-lactalbumin in Saanen, Toggenberg, and Alpine milk were 14,194±27.2, 14,266±105.9, and 14,241±13.2 m/z, which were not different from those of the bovine milk. The respective MW of ß- lactoglobulin in corresponding caprine milk were 18,840±31.5, 18,856±26.3, and 18,857±21.3 m/z, which were higher than those in the bovine milk. The MW of ß-casein in corresponding caprine milk were 23,860±27.2, 23,886±12.3, and 23,901±8.4 m/z, which were lower than those in the bovine milk. The results indicated that matrix-assisted laser desorption/ionization time-of-flight mass spectrometry could be used for rapid determination of MW of Korean caprine milk proteins without protein separation steps.

Comparison of the hemostatic efficacy of the endoscopic hemoclip method with hypertonic saline-epinephrine injection and a combination of the two for the management of bleeding peptic ulcers.

BACKGROUND: The endoscopic hemoclip method is a safe and effective hemostatic method for managing bleeding peptic ulcers. We compared the hemostatic efficacy of the endoscopic hemoclip method with that of hypertonic saline-epinephrine (HSE) injection and a combined method in the management of bleeding peptic ulcers. METHODS: From July 1994 to July 1997, we conducted a randomized clinical trial of endoscopic hemostasis involving 124 patients with actively bleeding or visible vessels at endoscopic inspection. RESULTS: Patients were randomly assigned to hemoclip (41 patients), HSE (41 patients), and combined treatment groups (42 patients). Initial hemostasis was achieved in 97.6%, 95.1%, and 97.6% of cases, respectively. Recurrent bleeding developed in 2.4%, 14.6%, and 9.5% of cases. Emergency operations were performed in 4.9%, 14.6%, and 2.3% of cases. The hemostasis rate was 71.4%, 50%, and 66.7% for spurting hemorrhage in each group. Permanent hemostasis was achieved in 95.1%, 85.4%, and 95.2% of cases. Three patients had complications, all in the HSE group. CONCLUSIONS: The hemoclip method is an effective hemostatic procedure and is safer than HSE injection. The combined method does not provide substantial advantage over use of the hemoclip method alone in the hemostatic management of bleeding peptic ulcers.

Serum alpha 1-antitrypsin in patients with hepatocellular carcinoma.

To evaluate the diagnostic value of alpha 1-antitrypsin (alpha-AT) as a tumor marker for hepatocellular carcinoma (HCC), we studied the serum levels of alpha-AT by rocket immunoelectrophoresis and alpha-fetoprotein (alpha-FP) by radioimmunoassay in 46 proven HCC patients, 43 cirrhosis patients and 200 healthy blood donors. The mean alpha-AT level of the 46 patients with HCC (4.8 +/- 2.7 mg/ml) was significantly higher than that of 200 healthy control subjects (1.7 +/- 0.7 mg/ml) (P less than 0.0001). The sensitivity of alpha-AT in 24 patients with high level of alpha-FP (greater than 400 ng/ml) and 22 patients with low level of alpha-FP (less than 400 ng/ml) were 96% and 64%, respectively. There was no substantial correlation between alpha-FP and alpha-AT in the two groups (alpha-FP greater than 400 ng/ml, alpha-FP less than 400 ng/ml) (r = 0.078, 0.064). The sensitivity for HCC using alpha-FP level alone (greater than 400 ng/ml) was only 52%, and the sensitivity using alpha-AT level alone (greater than 3.2 mg/ml) was 76% of the 46 patients. Combining both tests, sensitivity was improved only to 80%.