Isolation and Characterisation of Cocoa Protease

This project was initiated with the intent ion of isolating and characterising protease from cocoa beans,Theobroma cacao Linneaus because a greater knowledge of the proteases present in cocoa beans would lead to a better understanding of the problem of inferior cocoa flavour in Malaysian cocoa beans . The ammonium sulphate fractional precipitation method was used to isolate the cocoa protease while the partial purification of the enzyme was achieved by gel filtrat ion through Sephadex G-200. Four fractions precipitated with 0-20%, 20-40%, 40-60% and 60-80% saturations of ammonium sulphate were found to be proteo lytically active against casein . Further studies were conducted on the fractions precipitated with a -20% and 20-40% saturations of ammonium sulphate.Studies on the isolat ion procedure showed that the add it ion of sodiumdodecyl sulphate (SDS )or Triton X-lOa detergents did not enhance the efficiency of the isolation process. Temperature studies showed that both the 0-20% and 20- 40 % fractions have temperature optima of 45-50°C but were unstable at those temperatures. Both fractions possess more than one pH optima against both case in and bovine serum albumin (BSA). The pH optima are in the strong acidic pH and strong alkaline pH ranges. Inhibit or studies showed that both the 0-20% and 20-40% fractions are likely to contain cysteine proteases while not ruling out the presence of a spartic proteases. The passage of the 0-20% fraction through Sephadex G-200 produced two proteolytically active protein peaks designated as Pl and P2 while that of the 20-40% fraction produced five activity peaks which were not well separated. Studies with sodium dodecyl sulphate polyacrylamide gel electrophoresis (SOS-PAGE) showed that the 0-20% fraction was relatively pure and that the Pl peak was likely to be a protein aggregate. The characteristics of the proteases in both fractions strongly indicate that these enzymes do play a role in the production of cocoa flavour and its precursors during cocoa fermentation

好酸性細菌 Acidiphilium organovorum 由来のアラニンセマーゼ

Alanine racemase(EC 5.1.1.1)was screened from several acidophilic bacteria.Acidiphilium organovorum 13H showed the highest activity and was chosen as the representative source to study alaine racemase from acidphlic bacteria.The enzyme was found to be localised in the cytoplasm of the bacteria.Relative molecular mass syudies indicated that it had a dimeric native structure with identical subunits of about 34 kDa each.Maximum activity was observed between 50 and 60℃and at pH9.There was no loss of enzyme activity even after incubation at 65℃.The loss of activity upon dialysis against pyridoxal 5'-phosphate-free buffer containing hydroxylamine,and its partial recovery upon subsequent dialysis against buffer containing phyridoxal 5'-phosphate suggested that the enzyme required piridoxal 5'-phosphate as a co-factor for its catalytic activity.Acidiphilium属好酸性細菌中のアラニンラセマーゼ活性を検索した。Acidiphilium organovorum 13Hが最も高い活性を示したので、好酸性細菌由来の代表的なアラニンラセマーゼとして研究対象とした。本酵素の局在性を調べたところ、細胞質に存在することが明らかとなった。また本酵素は同一のサブユニット（約34ｋDa）からなる二重構造体をとることが示された。至適反応条件は50-60℃、pH9であった。また65℃で30分のインキュベーション後も活性が失われず、熱さに対して比較的安定な酵素であった。Hydroxylamineによる透析で活性が失われ、これをpyriodoxal 5'-phosphate を含む緩衝液により透析をした結果、活性が部分的に回復したことから、本酵素はpyridoxial 5'-phosphateを補酵素として要求することが示唆された

Securing Bring-Your-Own-Device (BYOD) programming exams

Traditional pen and paper exams are inadequate for modern university programming courses as they are misaligned with pedagogies and learning objectives that target practical coding ability. Unfortunately, many institutions lack the resources or space to be able to run assessments in dedicated computer labs. This has motivated the development of bring-your-own-device (BYOD) exam formats, allowing students to program in a similar environment to how they learnt, but presenting instructors with significant additional challenges in preventing plagiarism and cheating. In this paper, we describe a BYOD exam solution based on lockdown browsers, software which temporarily turns students' laptops into secure workstations with limited system or internet access. We combine the use of this technology with a learning management system and cloud-based programming tool to facilitate conceptual and practical programming questions that can be tackled in an interactive but controlled environment. We reflect on our experience of implementing this solution for a major undergraduate programming course, highlighting our principal lesson that policies and support mechanisms are as important to consider as the technology itself.Comment: Accepted by SIGCSE 202

An integrated approach in the discovery and characterization of a novel nuclear protein over-expressed in liver and pancreatic tumors

10.1016/S0014-5793(01)02409-7FEBS Letters4962-3109-116FEBL

Hcc-2, a novel mammalian ER thioredoxin that is differentially expressed in hepatocellular carcinoma

FEBS Letters58092216-2226FEBL