Alignment-Free Method to Predict Enzyme Classes and Subclasses

The Enzyme Classification (EC) number is a numerical classification scheme for enzymes, established using the chemical reactions they catalyze. This classification is based on the recommendation of the Nomenclature Committee of the International Union of Biochemistry and Molecular Biology. Six enzyme classes were recognised in the first Enzyme Classification and Nomenclature List, reported by the International Union of Biochemistry in 1961. However, a new enzyme group was recently added as the six existing EC classes could not describe enzymes involved in the movement of ions or molecules across membranes. Such enzymes are now classified in the new EC class of translocases (EC 7). Several computational methods have been developed in order to predict the EC number. However, due to this new change, all such methods are now outdated and need updating. In this work, we developed a new multi-task quantitative structure–activity relationship (QSAR) method aimed at predicting all 7 EC classes and subclasses. In so doing, we developed an alignment-free model based on artificial neural networks that proved to be very successful.

Pancreatic Enzyme Supplementation in Acute Pancreatitis

This study evaluates the effect of oral pancreatic enzyme supplements on pain, analgesic requirement and the incidence of complications in patients with acute pancreatitis. This double blind, prospectively randomised placebo controlled study included 23 patients. Pain was monitored using a visual analogue scale; the analgesic requirement was assessed with a numerical score.No significant differences were noted between the median (range) pain scores of patients who received placebo: 22 (17.1–58) and those who received enzymes: 23 (11.3–63). Hospital stay was 7 (5–10) days in patients on placebo and 8 (6–24) days in the enzyme group (p = 0.069). Analgesic requirements were: placebo 20 (6–60) and enzymes: 16 (0–63) (p = 0.56). This study has shown no beneficial effect of oral pancreatic enzyme supplements in the initial management of patients with acute pancreatitis.

The role of the metal ion in the mechanism of the K+-activated aldehyde dehydrogenase of Saccharomyces cerevisiae

The effect of K+ on assays of the enzyme was studied and it appears that the activation occurs slowly by a two-step process. Kinetic measurements suggest that the enzyme-catalysed reaction can proceed slowly (0.4%) in the complete absence of K+. The enzyme exhibits a K+-activated esterase activity, which is further activated by NAD+ or NADH. Stopped-flow studies indicated that the principal effect of K+ on the dehydrogenase reaction is to accelerate a step (possibly acyl-enzyme hydrolysis) associated with a fluorescence and small absorbance transient that occurs after hydride transfer and before NADH dissociation from the terminal E-NADH complex. The variation of activity of the enzyme with pH was studied. An enzyme group with pKa approx. 7.1 apparently promotes enzyme activity when in its alkaline form.