An experimental method to determine the substrate protection of enzyme against deactivation in a reversible reaction

Pathogenic Mechanisms and Therapy Development for C9orf72 Amyotrophic Lateral Sclerosis/Frontotemporal Dementia

In 2011, a hexanucleotide repeat expansion in the first intron of the C9orf72 gene was identified as the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). The proposed disease mechanisms include loss of C9orf72 function and gain of toxicity from the bidirectionally transcribed repeat-containing RNAs. Over the last few years, substantial progress has been made to determine the contribution of loss and gain of function in disease pathogenesis. The extensive body of molecular, cellular, animal, and human neuropathological studies is conflicted, but the predominance of evidence favors gain of toxicity as the main pathogenic mechanism for C9orf72 repeat expansions. Alterations in several downstream cellular functions, such as nucleocytoplasmic transport and autophagy, are implicated. Exciting progress has also been made in therapy development targeting this mutation, such as by antisense oligonucleotide therapies targeting sense transcripts and small molecules targeting nucleocytoplasmic transport, and these are now in phase 1 clinical trials.

Temperature optimization for reactor operation with chitin-immobilized lactase under modulated inactivation

Temperature effects on all kinetic and inactivation parameters have been determined for chitin immobilized lactase from Kluyveromyces marxianus var. marxianus, and proper temperature functions have been validated. Maximum reaction rate, Michaelis constant referred to lactose, inhibition constant for galactose and inactivation rates increased with temperature. Enzyme inactivation was adequately modelled by a two-stage series mechanism. The effect of galactose and lactose on enzyme inactivation was determined in terms of modulation factors that were positive for galactose and negative for lactose over the whole range of temperature studied. Modulation factors were mild functions of temperature in the first stage and strong functions in the second stage of CIL inactivation where galactose positive modulation factors increase with temperature and lactose negative modulation factors decrease with temperature. Temperature explicit functions for all kinetic and inactivation parameters were incorporated into a scheme to optimize the temperature of operation for a sequential batch reactor with chitin-immobilized lactase, based on an annual cost objective function for reactor operation. Software for temperature optimization was developed creating a friendly interface with user that allows the introduction of variations in all parameters and operational criteria to perform sensitivity analysis.