Engineering homoaromatic substrate specificity into aliphatic-specific Geobacillus pallidus RAPc8 nitrile hydratase

Magister Scientiae - MScGeobacillus pallidus RAPc8 is a thermophilic nitrile-degrading isolate, obtained from thermal sediment samples of a New Zealand hot spring. The G. pallidus RAPc8 NHase gene has been cloned and expressed in E. coli. The recombinant NHase exhibits nitrile-degrading activity at 50 °C, capable of degrading branched, linear and cyclic heteroaromatic nitrile substrates. However, no activity was found on homoaromatic nitrile substrates such as benzonitrile. In the present study, high levels of activity on benzonitrile were detected with a double mutant βF52GβF55L. Kinetic analysis on the mutant enzyme showed an 8-fold decrease in KM with benzonitrile (0.3mM) compared to acrylonitrile (2.6mM). Specificity constants (kcat/KM) of 5900 and 450 s-1.mM-1 were obtained for the double mutant on benzonitrile and acrylonitrile respectively. The amino acid residues lining the substrate channel were identified and the geometric dimensions measured. Cavity calculations revealed a 29% increase in volume and a 13% increase in inner surface area for the substrate channel of the double mutant when compared to the wild type. Surface representation of the wild type structure revealed two extended, curved channels, which are accessible to the bulk solvent from two locations in the heterodimer. The removal of the βF52may have contributed to the presence of a single channel with two opposing openings across the dimers with no internal blockage. Normal Mode Analysis calculations also indicate a higher intrinsic flexibility of the mutant relative tothe wild type enzyme. The increased flexibility within the mutant NHase could have introduced a functionally relevant aromatic substrate recognition conformation.South Afric

Contingent Convertible "CoCo" Bonds in Bank Risk Management Empirical Pricing Comparison

This work compares the performance of three pricing approaches on the CoCos issued on 21st of April 2014 by the China Merchants Bank (ISIN: CND100007RX8) through model fitting analysis with CoCo market prices. The bond specifications have been drawn from Moody’s CoCo Monitor Database. With an observation period from 10th of May 2014 to 31st of July 2015; a total of 284 trading days, the daily computed CoCo prices from the Credit Derivatives Approach, the Equity Derivatives Approach and the J.P. Morgan Model are determined using Moody’s Analytics. Based on RMSE and MASE measures, the J.P. Morgan Model is found to be significantly superior to the other valuation mechanisms while the Equity Derivatives Model is observed to be least-performing. Overall, the impact of integrating risk dynamics in the models, though positive except for the Equity Derivatives Model, is less pronounced probably because of a relatively sound financial environment prevailing,. The results of the Equity Derivatives Approach favoring the model in the absence of jumps were interpreted as either the ambiguous effect of option values or the addition of excessive risks in the valuation mechanism by the jump version model to the non-jump model. The assumption of constant conversion intensity for the Credit Derivatives Approach appears to be too simplistic and far-fetched from reality; empirical analysis supported a piecewise constant parameter instead. While the models fairly explain market prices, they generate lower CoCo prices than the actual market values. Three contingencies are subsequently inferred; the models allowing for more risks than actually required, the China CoCo market being culturally more risk-seeking, or the presence of an excessive demand for CoCos from yield-hungry investors. Further studies are anticipated for any possibility of generalization

A qualitative study on the factors affecting the valuation of football players in Europe

Football players have seen their market values increase drastically over the years. They have seen their importance grown in the books of football clubs and with the advancement of technology and analysis of football players both on and off the pitch, variables also known as factors have influenced their market values. The study provides for an in-depth analysis of the transfer market especially from 1990 onwards which represent the period from when transfer fees skyrocketed and the analysis of the current factors that have been found to have more effect on football players valuations. Furthermore, the research also discusses about other factors which may impact valuation calculations and recommendations on how the other factors should be considered and evaluated as well as the implementation of a regulation

Tackling the COVID-19 pandemic in paradise : the Mauritian experience

Non peer reviewe

Predictors of Hypertension in Mauritians with Normotension and Prehypertension at Baseline : A Cohort Study

Information on the predictors of future hypertension in Mauritians with prehypertension is scant. The aim of this study was to analyze the 5-year and 11-year risk of hypertension and its predictors in people with normotension and prehypertension at baseline in Mauritius in 1987. This was a retrospective cohort study of 883 men and 1194 women of Mauritian Indian and Mauritian Creole ethnicity, aged 25-74 years old, free of hypertension at baseline in 1987 with follow-up examinations in 1992 and 1998 using the same methodology. The main outcome was 5- and 11-year risk of hypertension. Odds ratios (OR) and corresponding 95% confidence intervals (CI) were calculated. The 5-year risk of hypertension was 5.4-times higher in people with prehypertension compared with normotensive individuals at baseline. The corresponding odds for prehypertensive people at baseline regarding 11-year hypertension risk was 3.39 (95% CI 2.67-4.29) in the adjusted logistic regression models. Being of Creole ethnicity (OR 1.42; 95% CI 1.09-1.86) increased the 11-year odds of hypertension compared with the Indian population. It is of importance to screen for people with prehypertension and implement strategies to reduce their systolic blood pressure levels to the recommended levels of 120/80 mmHg. Special attention needs to be given to Mauritians of Creole ethnicity.Peer reviewe